Understanding Key Concepts Of Java Coding

1. Introduction: Hi guys and welcome. My name is Michael. I'm a photographer, cinematographer, and a physicist. And in this course, I'll be exploring with you guys some tips and tricks that you can definitely use to up your coding or your programming. Level. Rise will be primarily dealing with Java. And this course is intended for intermediate groups of people. That means that you have some basic understanding of what Java is. But we're still developing some fundamentals with it. Just did an intermediate stage. So there's a bit of some background that you need to have. And I hope to see you in the next lesson. 2. Conditional Statements: Alright guys, I'm glad to have you here. And just a reminder that this course assumes that you already have some basics of coding in Java, right? And what we're gonna do is we'll just start off right here with conditional statements, right here, the up right here, conditional statement. And remember that's a comment right there. And we'll particularly start off with if else statement. If dadadadada means we put a condition right over there, and then we'll say else over there. And then we also put a condition of what should happen, right? And inherently, Java is well able to support quite a number of some logical conditions from mathematics, right? Whether it's logical conditions like maybe something like less than, let's say less than. And remember that we, we show, mathematically speaking, we show less done by something of the following scenario. We say a is less than b, for instance, right? And then we could have another scenario where we have less than or equal to, right? And that one would obviously have to be in the following fashion, where we would have to say maybe a is less than or equals to b. Then we could also have a scenario where we talk about greater than, greater than, which would then be referred to as a being greater than b. And you can definitely be able to track on top what I'm going to say an x greater than or equal to, which would then be referred to or shown rather in the following manner where we say the same pattern is greater than or equals to b. Then we could also have a scenario where you talk about it being equals to something and how we refer to that as we say, a is equals to fact, let me just do this. Well, I say a is equals to a is equals to b, not, and I repeat not. A is equals to b. Encoding a is equals to b means that you are saying a is to be replaced by b. It means equal, literally means insert. You see, but when you say equals, equals, it means that you actually referring to the mathematical notation or equal to, right? Which is what you would want to put perhaps in the scenario of conditions. Then you could otherwise show that something is not equals to something by saying not equal to. And then let's have that and say a is equals to b. So definitely there are quite a number of conditions that you can definitely use. And based on what you want to you, you can come out with different performances or actions to achieve, alright? And another thing that you might just want to be aware of is that Java itself has the following conditional statements. So here they are conditional statements. From Java itself. We have if condition. We have the if condition, condition. And this is to do what? This is to specify a code to be executed. It's as simple as that really. If a specified condition is true, if condition is true, right? So essentially would be able to have this if condition, right? And let me allow me to just put it in these two brackets here just so that it stands out as an as a condition itself. You're not able to confuse it as if it's just one continuous sentence. No. We use if to be able to do that. I could even put that use here. We use f to do this and then we could also use else, else to specify a code to be executed as well. Alright, let me just do this. But if a condition is false, you see that? So here this is perfect. If condition is true, no else means that if the condition is false. So that's how you use it. And then we could also talk about else if, which is also a condition. Therefore, I should put a bracket. Else if we use else if. And with the condition being condition. And that's when we want to specify a condition to be tested. To be tested. That's if condition is false, right? So essentially what usually happens is that would probably have something like this condition first, which is the if condition. And then next would have else-if. And then finally we would have this one else. That's if all conditions are happening, then we go to finally the else. That's usually the order in which would have one worry. We'll definitely be looking into this just shortly after this. This is just a presentation of this methods. And then we also have a switch condition which is used to specify there is a condition over there, right? Typo, which is definitely used to specify what many, many, many alternative blocks of code to be executed. This comes in very handy, especially into a machine learning or data science or anything of that. You will find yourself using this a lot of times really, just to delve in deeper into the whole idea of the if statement. Let me give you a bit of some some, something interesting, Garrett. Let's have a look at the following. Let's just say we're looking at if now if condition. And with this if condition, what we're gonna do is write this. 3. If Conditional Statements: What we're gonna do is we're just going to put a condition over here and say if. And then we put our condition if for example three is greater than one. That's an example. Question is, now, if that's the case, what should happen? What should happen if that's the case? So you could tell it mixed for example, system. Remember to put it properly system. Dot out, dot, print, LN, print. Let's print a string that says first number greater than second number. Right? So essentially what I'm telling my, my, my, my Java here to do is if the first number, which is three, is greater than the second number, if that condition is true, then this should be printed out. This is what I should see. And if it's false, the question is if it's false, then what should happen? Well, nothing because I didn't tell it what should happen if nothing, if this condition is false. So let's just try and run that and see with java will be able to print out what we expect it to print out. There is first number greater than the second number. Now, don't be moved by this HelloWorld. That's because of this right here. I could just easily very simply delete this. We don't really need it. Honestly. I could run it again just so that we are convinced that we just have that as first number greater than the second number. Really good. So consider the following scenario. I, I put my one here and I put my 3M. Now, let's predict what should happen. Inherently, we know that one is not greater than three. And therefore it means this first condition is not true. And remember that if condition is used to specify a code that is true, if that condition is true, then code will be executed. But then in our scenario over here, this condition is not true, right? So let's see nothing. Why nothing? That's because the condition is false. Definitely false. But then Java is wondering, now if it's false, what should I do next? Since we didn't specify what it should do next, just summarized nothing. What we should do is we should say else. We could say else if, or we could say else. But I'll start off with else. It means if the first condition is not true, if it's false, therefore, what should happen? That's where else comes in. And then I say system, out, dot, dot, out, dot, print LN. And we have first number, smaller than second number. So let's see now let's run it. Essentially, we're saying if this is false, then this should be upheld. Now, if this condition is not true, then obviously it means it's false. And therefore, if it's false, this here should be tested, right? It means if we don't do the first one, else are therefore we're going to do the following. So let's run it and see what we get. Walla, first number, smaller than second number. That's definitely true according to what we see here, the first number is smaller than the second number. And we could play around with as many values if we want. We could even play around with 100. And let's see 103, which one is greater? It's definitely hundreds, so it means the first number should be greater than the second number. Let's see. Voila, there it is. First number greater than the second number, right? So that's definitely the if statement over there, right. 4. Errors Associated With Conditional Statements: Then just take, take note though that there are some errors that people will do. Sometimes take mode that if you use uppercase, if like that, that means something else different way, then we'll give you an error. It's very important to note that, right? So you can think of it, or rather even Teslas that we've just done here. Not only for numbers really, you could even tested for variables. What if you add variables like, for example, let's say I were to say int x is equals to 25, like that. And I say int y is equals to 79. Then unlike right, semicolon over there. And then I have put if condition. Now I just open the bracket and I just say x is less than y, for example. Alright? If that's the case, then what should happen? This should happen. System. Then I say dot out dot print LN. And therefore we just say x is greater. Let's say x is less than, x is less than y. For example, if that's, if that's true, if that's true, then that's the case. Now, what do we predict to happen? Well, are inherently, we can see that x is definitely smaller than y because x is 25 and y is 79. And therefore what we expect to see is we see over there, it's, this should be held true. This is true. If this condition is true, then this is what's going to be printed and it is true. And therefore what we expect to see is x is less than y. That's what we expect to see. Now, what we wanna do here, remember, is want to put this in comments just to ensure that we don't get answers from the previous thing showing as well. We just want this portion and viola data's X is less than y, right? Awesome. I hope that it's making sense for you guys. It's written the most important thing. 5. Else Statement: And right then we'll, we'll just quickly move on and see if we can just toggle on the L statement. Alright, We're just understanding the else statement even further. The focus has been primarily on the F. Now we'll focus on primarily on the else statement. As I already mentioned, the else statement is just used to specify a block of code to be executed if the condition is false, right? So you can think of it like, let's say, for example, were to say end and then we talk about time. That is equals to maybe 40 minutes, maybe, right? And we then say, if time is less than 60 minutes, an hour, right? If, if the time is less than 60 minutes, what should happen? Well, if that's the case, then I'm early. The student is LE maybe if this was a case where a student getting arriving late for an exam, whether it's 40 minutes early, or rather 40 minutes late or 60 minutes. 60 minutes beyond time. Obviously the student is lifted away, but it's just a matter of which one is better between the two. So we'd probably print something like, hey, if the time is less than 60 minutes, then the student is not that late. Know if this is advisable, but hopefully the student will not be late at all. Student is not that late. That's if it's less than 60 minutes. And let's see. Remember, that's because the first one here is appearing because we didn't put comments in it. So let me just put comments there and then we can focus on the second one without any distractions. So there it is hidden and the student is not that laid here as we can see it. That's because again, the variable here, what Java does is that it understands. Remember we spoke about how the equals sign and essentially just means insert whatever I see time, I have inserted 40 into time whenever time is mentioned to Java, java quickly understands that This isn't really time. This isn't really the time we're talking about is 40 if the integer, all the whole numbers for t. And therefore, according to a condition that we have here, the student is not dead laid. And then we tweak it. We tweak it. How do we tweak it? We say else now, we say else Now. Else. It means that if this condition is not upheld, student is late. Friend, Ellen, student is late. This would apply in the following scenario. Imagine I were to say, which one is Alia being printed minutes late of 40 minutes late? Which one relatively as Ellie, obviously 20 minutes, right? Therefore, the student is now the lead if he is 40 minutes late. For example, in our scenario here it means in therefore is for t less than 20, no any, That's what we're saying here. The condition is if for t is less than 2040, represented by the time, the variable of time. If that's the case, then this is what's gonna be printed. But that's not true. What is true now is that for t is greater than 20, and therefore that falls in the else statement because here it's false, and therefore whatever is false here will be executed down here. So let's run it and see we predict student is late, voila. There it is. There we have it. Student is late. Beautiful. I hope it's just making even more sense for you guys. 6. Else..if Conditional Statement: Go quickly into the else. Let me just put this as a common. The else, if that is the ELF, the else-if condition. And with the else-if condition, really what's actually happening here is that what's actually happening here is that we have the following scenario right? There. We have it, for example, we're going to apply exactly what we just did here. Just take it with us down here to just understand much better. So let me just put this one in comments because we don't need it anymore. I could always just literally just console this and yeah, it's okay. So we haven't following scenario. Now, think about it. What if, if The time is less than ten, then this is what will print LE or maybe Good morning. Let's change that a bit. Just to understand. Better. Afternoon, for example. Or other here it's evening. Evening. It means that whatever time I have here, it's a fairly binary situation. If it's less than ten, the time is less than ten, it's morning time. If it's greater than ten, even in dire automatically. Right? But then the else if comes and says, Hey, what if I want to say else? If? Let's say else-if. And then we put our condition and we cells if time is less than, what if it's just less than 30 minutes? Well, in this case, what will happen is you just let me just copy this line here so that we don't have to keep writing it every time when we see it. Then here it would just be the afternoon. Afternoon. So literally what's actually happening here is that we're saying if the time is less than ten, it's morning. If it's less than 30 in the afternoon. And if it's greater than what? Than T, meaning it's not less than ten and it's not less than 30, then it definitely means it's greater than Theta, right? And you probably are wondering why would we need the LCF? Well, you see when you make it just if then else, It's a very arbitrary or rather a very binary situation, its limits you so much because it's really an option, a, I'll be. But then the beauty of else-if is that it allows you to add more conditions. Therefore, you can add options a, B, C, D, E as many as you want. You can add as many else ifs if you want. Now, if I have a time that's let's say I had a time that was what? Literally five. Maybe. If I have five, it means it's less than ten, right? The first condition is satisfied. It means what in Java runs that you might say to me, but then five is also less than 30, E13. Print this message. Well, when Java runs it, he's starting other stuff literally from here, checks here. Is this true or not? And then if it's not true, he moves on. But then if it is true, then Java will just execute whatever code that is in there that is definitely right here, right? But then if it's greater than that, it will come here. So in this scenario, we predicted to be in the first scenario. Therefore, we expect it to tell us about the money and datas morning. That's because it ran this first one is, notice that hey, five is less than ten, therefore money. But then what if I add plus ten? Make it 15 now? Now it's greater than ten. It means it will check first-year and verify and say, Hey, this is false, this is not true. And once it does that, what does it do? It skips and goes here and verifies hens is here. What about this area? Else if time is less than 30, is 15 less than 30. And it says, Yeah, it is. And therefore it's going to print afternoon. So let's run it and see. There it is afternoon. And definitely true, able to see the trend if I were to increase this by printing here and just make it better five now, it means you will check here first and say, Is that a five less than turn? It will say possible that's false. And then move on and check is five less than 13 not true as well. And then you also now just say false. Then it will finally come over to the else here and say, if this one is not satisfied and this one is not satisfied, then it definitely is going to be solidified here. So therefore, this here will be true and we predict, therefore, for our code here to be run, our string to be shown here, our text to be shown here to be what? Evening. So let's run it and see. And voila, there it is. So I hope this has helped you guys and I'm going to move on to another thing now. 7. The Ternary Operator: Right? So the next one that we'll be looking into is still unconditional statement, but I just want to show you more shot way of dealing with the whole if else conditional statements. And this here brings us to what we call, I'm going to make use of the ternary operator. And worry not. We're gonna be explaining this shortly, but it's called the Java. Let me just put it davon shorthand. If else. Alright, so that's the Java shot and evil. So it's more like a shorthand which is a ternary operator essentially. And you're probably wondering what the operator hears itself. Here's how we spell it. It's a ternary operator. And a ternary operator really is just a ternary operator because it consists of three operands. Operands are, you will see them shortly as I, as I'll be texting them. So think about the following scenario, which is what we had. Think about it like this. Let's say you had something like end and time, like we did in the first scenario and we went to give this a value of 30 for example. And then say if the time is less than Twain t, then what should happen is, what should happen is we should print it out, right? It should print out what? Maybe something like good day. Or if that's not the case, what should happen? So we write else and then we say, this is literally what we just did. We could print out the print and now we could print out maybe a good evening. Yeah, this one's well, we already spoke about this and nothing's particular bothered now at least because we've already done it before. And I definitely gonna be a good evening because 30 is greater than 20. That's a long way of writing this way. Using ternary operators, or really this shorthand rule that we're about to use. You can simply replace all of that instead of writing it that way, what you could do is you could just literally write it like this and just say end time is equivalent tool. Let me just put them in operator here and say end time is equals to three, as we said in the previous case. And then we change that bed shear strain. And then we say result. And then we say, it's equivalent to time, alright, which is less than t. Then we literally from there just put a question mark over there. Just like that. And we put the question mark. We even have this here where we say, good day. Just like that, even put a dot. And we don't need a dog necessarily really, it's just the mean was putting a dot. And then we could also have something like Good evening here. But just in as a string, because that's what we define this as. It's a string. Evening. Alright? Then we just close it up like that. As you can see, there is no error. So it means Darwin's life. I understand what you're saying. And then I just put an odd Print and result. So instead of writing it this long way, as you can see, this takes how many lines? 12345 here, three lines. Probably wondering why would we, what's the point if it does the same thing with the point? Well, the more you really delve deeply into the whole coding, you'll see that sometimes is you would come up with thousands of lines you see. So it's just easier sometimes if you can find abbreviated forms of those lines or codes, right? So let's see again, good evening. You see that? So that right there is an application of the shorthand rule or the ternary operator, right? 8. Switch Conditional Statements: That brings us then to the next point. Let me just put some comments. Our next point has got to do with the conditional statement of switch. Switch conditional statement. So for such conditional statements, we use them to select one of many blocks of code to be expressed. How it works is like this. How it works essentially is like this. Here is an error because this guy should be down here. Yeah. Yeah, good. Assault house, which essentially works. It's like this, right? The switch code, let me just put this in. We're going to make some commentary here. The search code. Rather the switch expression is evaluated, right? What's the value of the expression is compared with values of each case. Alright, so comparison for values of each case is done, right? Then we also have if there's a match, for example, if there's a match, we'll have the third stage, which is if there is a match, the code will be executed. And there are some words, keywords like break. The break, we use keywords like this one here, the break and default. This are some keywords that we use, this optional, right? And this has some keywords to note. And I'll elaborate them moist. We keep on going, right? And the key thing to note here is really, as we'll see, particularly now with an example, is this really, this really is the main vein. So an example, let's say we talk about, hey, they default, for example, or rather the five and preferably five over four. And then we talk about a switch and then we say, day, this is how we do it by the way. And we'll just open up our statement of there are conditional statement, we run it through case number one. And in case number one, what we do is we look at case number one. We can go down and then we say, Hey, this is the first case, then print Monday, for example, the days of the week. And if this isn't the case, if, if if what, our condition is not one, therefore, you will not print Monday. We are going to tell Java to go out of this loop or this conditional on case here and come to case number two and check a two. So it's taking with this values here, it's trying to match these values here to what we initially have over there. So it's going to come here and allow me to just copy and use this so that I can do this much faster and say it's gonna be Tuesday, the second day of the week. And in case number, I mean, definitely we're going to put a break. So if you don't put a break, it will hit the devil will not properly understand as to how to properly do or what to do in this scenario. You see? So it's just always wise to use it in the following manner. All right, so, so we have dot over here out of print. We have wildness day and that we have a break. And we have kaizen before given by Thursday. With break. Yeah. So as you can see this definitely way more lines over here That's mucus with specifying a whole lot of conditions. Lloyd, case number five, I think I'll probably stop at Kids number seven. So just bear with me here. Friday. It's Friday over there. And just coffee break here as well and case let me just copy all of this should be much, much faster like this. Case number six and case number seven. And here's Saturday and Sunday. Sunday. Right. So what we expect this, since we're checking out the day over there, what's going to happen is that Java is going to run through, check, take the number five and scan it through with all these conditions here, it's condition 1234. And when it gets a match of five, as you can see, it's getting a Metro five already. There's five here and there's a five, whether it's already highlighted. It's going to print Friday. So let's run it Friday. Alright, so beautiful. That's generally how we just work our way around the whole Java code. Whole Java code when it comes to conditional statements, that is, conditional statements. 9. Java Loops: Alright, so the next thing that we are going to look into is what we call Java loops. This is a Java loops, especially we'll start off with the while loops, means that quite a number of loops. But we're going to focus on the while loop. And loops themselves. Molecule like how we define the loop in English, it's something that's almost, you could say repetitive rate. They can execute a block of code as long as the specified condition is reached. They're very handy because they save time, reduce errors in the main code more readable. And the Java code, it's same texts can be seen in the following manner. So let me just put the comment over here just so that we can have this included a comment here. See, good. Alright. Syntax for this would be given by, let me just have it right down here for us, the syntax will be given by while condition. As you know, I love putting conditions in brackets like this. Just sort of be stemmed out and you know how to better use them. And obviously we're going to open up something over there and then we have a code to be executed here. And then we're going to close it down with this guy over here. So it means therefore this is probably all that you might need and just close it over there. Alright. So an example of this would be something like that. So let me just say, for example, int I is equivalent one. And I say, I give a condition while I is less than five or five, why not? This is what should happen. System. Dot out, dot, print, print I. Alright. So what's going on over here? What's going on so far is we are telling our code that while I is less than five, keep on doing the following. Keep on showing the value of I. And don't just stop there. Increase. And this is me putting the increase. I say e plus plus. I say a closet like this. Keep on going up. Make an increment of plus one every time. So Java will take one, check it against five and see that, hey, it's less than five, then what you will do, you take the value of 11 and print it as one, and then come down and add one to itself again and then go back to say, now I have one plus one. Now it's now two. And this is how to demonstrate it will be one, then one. Then you will have one plus one. And then you will have one plus one plus one. And then you will have one plus one plus one plus one. And then finally he will stop right there. Therefore, the values that you essentially get will be one plus two plus three plus four. You see that? So let's just run that for us and see what we get. So there it is, 1234. Those are the values that we get. And just remember that the reason why we stopped at four and we don't go beyond or like on a five or anything like that. It's simply because it's simply because we said less than five. If we had said less or equals to five, that would have been different because it means that five is included. But in this case, five is not included. So now that it is true that lets us see the difference. You'll see it gets to five. Let's see, datas from one to five. Now, you see that. So it's just a way that we we work around this. Just a bit of some caution over here, just please remember this. Let me just put it for you. Do not forget to increase variable used in the condition. Do not assume, right, not assume that. Just this alone is enough to cause the eye to keep on going up. No, it's not. It really is not. And it won't even know when to stop is either your risk on making an end, never ending loop really let me just remove this and just shrink something. Yeah. If I run this this way, Let's see what's happening here. It keeps on going 111111. Why does it do that? It keeps on doing this because it will just keep on an infinite level of it. That's why my computer is literally even struggling to see that it keeps on going down. I can even scroll down or up. I honestly cannot. The only thing I have to do in this stage is I can now just do this again. And I'll stop it right here as well. Stopped and run it again. The reason why that was occurring, It's because it's taking the value of one and then repeating to check again against the will of one. And every time it keeps taking the Villa of one and taking that button five, but one is less than five. So what should I do? I should print I, which is one. And it gives me that again and again. So it's an infinite loop. It will keep on doing that. It just won't stop. So you need to have this some of these conditions below it to give it, when should it stop? How should it know that it should stop? Wait. So when you give it this increment, you are saying keep going up, keep going up until you reach the spine, the statement here, and this is true. That's when you stop. You see that It's just very valuable and very important to to understand that as well, right? And just coupled with the while condition is what we call the default condition. And just the four condition. Let me just move those, put them here. Beautiful. So the four condition is quiet. One of those conditions that are used a lot and how they function really, it's like this. Let me just put it down for you. We call it the Java for loop. And we use this one when you know exactly how many times you want to go through a block of code. Instead of a while loop. While loop, if you don't know, when would it stop, right? So it's like you're putting a restriction. But for, you definitely know what's the beginning, you know what the end. And the syntax that we use for this one is the following. Really syntax is the following. We say for my just scroll down, we see four. We put statement one, statement two. And then we put statement three as well. Bear in mind that in-between here, we're putting semi-colons instead of just commas like that. We put semi-colons. And then as you know, we always just open up here and you want to close as well. And then here we just have a code to be executed. Executed. You're probably wondering at this stage what is called statement1. What does statement two, what does, what does all of that all about? Well, what this is all about really is this statement one, what it does is that it's a statement that really is executed one time before the execution of the block code gets executed. One time before the execution of the code. Then statement two. On the other hand, it defines what defines the condition. Condition, defines the condition for executing the code. And then finally the statement three. Statement three is all about, really is just it's the last stage you could say executed after the cold means after the code has been executed, of course, right? So an example of this would probably be something like this. Let's see if we can just find it over here and say, for x is equals to 0. Then we say statement two. We say I is less than or rather not I, x is less than seven. And then finally we're like, Hey. I'm the x keeps on increasing in the following manner, meaning it has an increment. And we just open up parentheses over there. And we print, we just print x. So just in prediction of what's going to happen here is we're essentially defining the value of x starting from, from, from 0. We define x is 0. Then we give it a condition to say while x is less than 0. And then keep on doing the following. What should keep on happening? Simply keep on adding one because it's x plus plus, which means an increment of one. So couponing going by, up by one again, again, again. So what Java will do is he would take the first value, check against seven and see that we have just 0, right? Then from there, he will just from 0. There'll be an increment of 0 plus one. Then again, keep on doing that again, 0 plus one plus one. And then again 0 plus one plus one, plus one plus one, and so on and so forth until it goes all the way tool to six because it's less than seven, it should not reach seven. So it's from 0 all the way to six. So it means when we run this, we should just see values doing this all the way to six. Beautiful, There it is. That's exactly what we expected it to do, and that is exactly what it has done, right? So that's just amazing, That's just amazing. Example that you can definitely think about or just find a value would be this right here. Let me just comment this and but, but, but, uh, right. Just comment on this and let's consider the following scenario. What if you had, for example, for end, I definitely itis time. Love French from me. Quite nice. I say it's less than or equals to maybe ten. And then I give it to the final act of simply going up by two instead of blast one. You see that? So now I'm going up by two and then I say system out, print LN and the managers say, Hey, print i. And what's going to happen here is you can just probably predict, is we're going to have the following. We're going to have 0, and then we're going to have an increment of plus two. So it will be 0 plus two. Alright? I hope you're already seeing where this is going. We're going to be 0. And then plus two, plus two, alright? The increment is true, it's not one, right? So it means our increment. Each step is going to be just by two. So we now have it at six. It's still not bigger than ten. So it's going to finally just stop right here too, as two plus two plus two. And find that this is eight, right? And what it will actually do is this, this is how it will actually do. Now, I'm just telling you with hindsight already haven't done this many times. It will check and say 0, and then check and sets now to record the value of true, print it out. It'll print a value of 0, print the value of two. Here it will print the value of two plus two, which is four here it will print the value of two plus two plus two, which is six. Here it will print the value of two plus two plus two plus two, which is eight. And then when it gets here, it says this is ten. It will run it through scan and say, wait, ten is ten less than or equals to ten. And then the answer is yes. Actually it is, because it's equals two. You see that? So it should actually be able to even take this value as well. I had actually not seen that I put an equal sign here, but because there's an equal sign, yes, it will definitely register. This is ten, so it will show 0246810. So let's run it and see for ourselves, there is 0248610. And just bear in mind that if I remove the equal sign, it's going to stop at eight is gonna be 0 up to eight. Var law, that is datas. It's just amazing. Beautiful. The next one that would definitely want to look into is called the Java each loop. Java each loop, Alright? And for this one, this is how we have it as Java each loop, that's how we write each, each from English really. For each group. That is for each, for each, not just each, for each should be for each all the time. Alright, so for this one here, the syntax for this is really the following nature. We say four and then we put the type of a variable. And we put the variable name here. And right over there we put an array name. And we open it up like that. And then we simply have our code. Here. This is code to be executed as always. Code to be executed is right over there. And yeah, just to please bear in mind that you need to close this, right? So remember, you'd probably want to have something like this over here. Alright, very important. And just, just like that, Let's try and see an example of this. Let's say we had a string containing names of costs, right? And let me just do this because my keyboard does not inherently have this, so I have to always change my key votes in order to do that. If you're on a computer or on a Mac that does not have the, the place of many buttons, you can always just change keyboards over here. Remember that? Then? We can always come over to the cars here. And just we have, for example, Volvo. We could have, for example, BMW. Yeah, you mentioned it could be VW, volkswagen. It could be for Americans would definitely love this one. It could definitely be maybe Honda, Japan. So you could also have that as well. And then right in here, what do we, what do we do? Well, we don't really open it up at this stage. It's when we start using the four that we start opening things up for now, this is just a list of ints, an array containing a list of data. So it's string, string I. Then we say cos. Yeah. Then we open it. Now. Now it's definitely the time to open. And then we say system out dot print, for example, right? So let's just, it means therefore in this scenario, let's just run it and we see there the beautiful. So it means that for each of the things that we see in a list, continuous lists like that, we were able to present each of them. So it means that Java was able to go through each of them. How java interprets this is like this. It's almost as if this is represented by a value of 0. And then the value one, value two here. But if three value four, and by simply doing this, we're telling you that it's a string. Print the value one, and then it will understand. So one is actually a string and it represents, it represents a string of Volvo. So it will print Volvo, represented by the value of 0, and then come to one and c1 is BMW and then come to two and c2 as vw, and then C come to three and then S3, S4, and then come to four. And C4 is a Honda, right? Ben mine that I started with 0 and that's how in Java always count starts from 0 and goes up. That doesn't stop here and see it as a one necessarily it sees it as a 0. So that's just something else to keep in mind and see its value as well as we're still on this very interesting topic. Interesting topic. 10. Java Break & Continue, Arrays: Alright guys, so the next thing that we're definitely going to want to address will have to do with what we call Java break and continue. So Java break and continue, it's still part of what we're still on right now. Definitely still part of that. And what we're gonna do with this, and you will see as well. For this, we have already seen the break statement used in an alien situation of what we've been talking about. And we used it obviously to jump out of a switch statement, right? We can use the break statement to jump out of a loop as well. Jump out of loop. And obviously that's going to be a comment. Alright? And the best way to demonstrate this would be, let's say you have something of the following nature. You were to say fall. And then you'd say end. I is equivalent to, let's say is equivalent to 0. And as you remember, whenever you have four, you need to have three statements. So let me just define a few more statements for myself here and see what I can come up with. Alright? Alright, and so forth. And then we say, if E is equivalent to four, right? Four like that, what should happen? Then there should be a jump out of that loop. So there we have it. And then what do I do next? I just say system dot out, dot print LN, and I have my eye over there. Alright, so let's just run it over here and see what we get from that. And voila, there we have it. We have the values from 0 up to three. And the reason why that is, is because we have simply told our code here, our software, java to do this, start from 0. And as long as this condition is satisfied off having a number that is less than ten with increments of one at each time. What should happen? The following should happen if I is equivalent to for the moment that I get up to the value of four, then stop. You see what Java does. It starts from 0, does this and notices that, hey, we're 0 is definitely less than ten. And then it goes and prints the value of any checks here as well. Definitely it will check here and check and say that, Hey, I is 00 is not equal to four. Therefore, there's no need to come to this break. It'll skip and come here and print the value of 0, and then go up by one and then take the value of one, check it against tag and see if it's larger or less than, and see that it's less than. Here again, check it against four and check if one is equals to four. And it will find out obviously it is not equal to four. So what it will do, it will jump again, print the value of one, so on and so forth, until it gets to the venue of, of, until it gets to the value of four. When it gets to the value of four, following is still satisfied, right? But then when it gets hateful, see that four is equals to four and then neutral. So therefore, I will break. It will stop right here and one come to print this value here. You see that? So there'll be no need to print this value right here. But if I were to say, for example, if I were to remove or if I were to have this print here and just say if let me print this here. If I were to print this and set it at four here, it should print the value of I. It would definitely register the value of four that was there, right? But yeah, it definitely makes sense. I hope now. Then we're going to continue and then talk about there it is. There's our comment over there. So the next thing we want to talk about is definitely the Java continue. They go hand in hand. It's a break and continue. So the continuous statement breaks one iteration in the loop. If a specified condition occurs and continues with the next iteration in the loop. So it's almost as if we're skipping that one area that perhaps we were looking to get. For example, in the very problem that we have over here, the various situation that we have over here. Let's just copy that and paste it right here. Instead of me putting a break here, what if I had put maybe continue? What what's the effect? Was the effect of definitely having a continue over there. And there's a bit of a problem, as you can see with my code over here. It's okay now we run that. And now not 0123, there's no false. We skip up to 56789. You see that? That's because we have said that when four is equals to four, contiguous, meaning skip it, there's no need to print it out. Just skip it and go back to this as well. So that's why it skips the value of four over there. So essentially That's how continue works. Awesome people. Then the next thing that we want to look at is probably one of the most essential ones when it comes to coding in that has got everything to do with what we call the arrays, java arrays. So let me just put that down for you. Java array. That is that, right? And with Java arrays, we use arrays to quite a number of things. Honestly. We can use them to, for example, store, store multiple values in a single variable. That's the beauty of it. Render it can stall. For example, it can store a collection of cars, collection of different peoples heights, all sorts of statistics really you can keep them and store them under one category, maybe people's heights and different colors you see. So the key thing to know is when you want to declare an array, you need to first define the variable type with square brackets. And how do you do that? Well, essentially you just do it like this. Obviously I'm gonna make an example, but just want to help you be familiar with the syntax. I have my square here. Let me change the keyboard and it is over here. Let me just open it up. This I can copy and pasted from some way I know because I had already used this, I believe today at some point. No, I have not used it yet. No problem. We'll just give it like this. And let me see on my keyboard where I can find a way to close that. So, yeah, that's the one right here. Alright. Beautiful. Alright. So we go like this as well. Excellent, Excellent. So if you're in a situation like mine where you don't have too much to explore on your keyboard. You can always use that visual cue bottom with it. And then you have cars, right? And it's a string of cars. And with this string of cars, really, you can store as many cars as you want in there really. Because when we have done this, we have now declared a variable that holds an array of strings to ints add values to it. We can just use an array literal and plays the values in a comma separated list inside curly brackets. How do we do that? Well, here now comes the example. So let me just yell and we say string. Let me literally take this example should be easier to do it with what I already have strain cars and then haven't changed my keyboard. Awesome. So screencasts and then we say is equivalent tool. And then let's place our cars over there. We could have, for example, Toyota, Ford from my American friends. But as you can see, it's in red. Why is it in red? Because it's not identifying it as a string. So we need to put those quotation marks over there. Awesome. So there it is. There it is. And then we could have Toyota, we could have FADH, we could have Ferrari, our Italians. We could have Mercedes Benz. We could have as many cars as we want, but I think this will be enough for now, really. And voila, it's as simple as that really. And this works not just for string oriented objects of course, or string subjects. We could also do this a bit for integers, that is for values as well, right? And how we do that is by simply doing this, just coming over to string, let's just copy that. And we have int. Now we have this and then we say my number. We can declare Nino variable like that. Then we open up and start storing values from ten to 20 to 30 to 40. It's up to us to be as free and as explorers as we want to be, right? So that's a cool thing. We start all these values in one place, my numbers, right? Then let's say that for example, you want to access elements of this array, right? Let me just write that down for us. Access elements of array. How would we do that? Well, to do that, or would have to do is, for example, let's say I wanted to access elements of this array right here, that's this area. How would I do that? Well, all I'd have to do is I'll just have to say system out dot print LN, preferably like printing them this way. And then selecting them as costs with our elements here and n here. In between my two squares over there. What I do is I can choose what to bring out, right? Remember when Java knows this, he knows this S. This S corresponding to 0, the set S corresponding to two as one rather this corresponding to, this corresponding to three, and so on and so forth. You see that if I were to say, for example, 0, what Java gets from that is, I need to print the first card that I find, right? Because it starts counting from oral to start showing outputs from 0. So let's go. We should see a Toyota voila. That is, we have a Toyota, right? If I were to say three, for example, three means if this is 0, this is one, this is two, this is 33 should be bends. So let's run it and see if we do get it bends, indeed, maturities. Yep, awesome. Mercedes Benz In deed, right? So let's say that maybe you want to do it. You want to change, let's say you want to maybe change an array element. An array element. How would you do that? Well, to change an array element, you just need to specify the element that you want to change, right? So for example, let's say that I wanted to change Ford been having quite a lot of for today. So let's change that just for the loan. So let's say cars and then select fought, which one is at 123 or four. There is no force 10123 actually. So we'll just pick on the first one, which is 01, which represents fought, and then say Cars 01 and then replace them by. How about Aston Martin? As to Martin? Aston Martin, de benign, deviant idea of a bit of a fan of cars, really sports cars. That is, we could have an replays are forward with an Aston Martin, right? So the moment that we now have this, all we have to do therefore, is we could just simply print cancer again. So we could just say instead of us printing ton number three, how about this? How about I take this guy again and place it here now after the change has happened and just register this as kirwan. That is because it used to be fought over there. But it has changed. It has become a stone Mountain. So we should have our stomata now, Aston Martin DB nine. So that's the beauty of it. Now you're probably wondering why I had to shift that. Well, let's say it was y t Actually, let's say one's right here. Let's run it and then we see what's going to happen over there. It's fought again. Why is that? That's because it's Java. It's reading the code here. It starts line by line. That's from 187188. So as far as 188 or 1921 is found, when I tell it to launch and give me what value one is here, it's getting forward because it's not yet understood or rather received information that it should change. That change only happens in line 194. So that's why I had to do what I did and just placing this down here so that when I run it, now it has understood that at 1 before there was a change. Now Cao Huan means and Aston Martin de be nine, right? So that's how we do if we want to change in ROE element. But what if we want to determine, what? What if we want to determine an array length, for example, for one reason or the other, it's possible when it's possible that you'd want to find out how many elements are there in an array. And for that, all you have to do 3D is just to use the length property. And how do we use the length property? Well, do this. So let me just use the same thing we've been using here, the system that thought. So I'll just come here. Instead of printing cars like that, I'm just going to say cars and the length, right? So when I do this, it should tell me how many elements are there. Bear in mind. It is not counting from 0123. No, no, no. It's counting how many values are in the first place. It's counting 0 and x1, it's gone to one, S2, S3 to S3, and its content three is four. So therefore, it should produce four elements are in the array, right? Because I'm asking it how many elements are in the areas where it says four elements IN diarrhea, which is true, It's 1234, therefore, right? So that really is that I hope that definitely helps. 11. Java Array Loop: Then the next thing that we want to look at is what we call the Java. Java array loop is definitely something we want to look into now. And we can loop through our array elements with a for-loop of costs. And we can even use the length property to specify how many times the loop should run. Right? So let's think about, for example, same, same, same situation that we have our string over here. Let's say that for example, we wanted to just run a bit of a loop over there, right? Just try and run out a bit of a loop. So what we could do is this. We could just take this here and place it where I can easily access it, especially this one, this first one about the cars, S1 about the cause. Alright, let me try and just write it again. Myself. Just over here. Alright. Here the arm, the cause. So here's our Again, let me rewrite that again. I think it's deleted itself java array loop. So let's say I have the following. Let's say I have a string and I have the following as well. This training alongside that, I have the following string with cars and let me just put this one now in bracket because I don't need this anymore really. So I'll just come down from here and move this one. Now. Move this one bit of some work going on here, but should be done in a minute. Alright? So what I do is now I introduce some bit of a loop here. I say int I is equals to 0. And right there I say I is less cost. And then they are length of course. And right then, then I just say I plus, plus. And I open this up for us to use. And as I open it up, right like that, I'm just going to print out and put this printing method in here just so that I can work out what's actually going on here. Now this time, I'm definitely not going to be printing in terms of car length and rather than using the E that has already been placed over there. But I'm definitely going to want to place it as well in my squares because it's an array that we're talking about over here. It's an array, so we don't want to lose sight of that. So that is my eye and it's ready. Let's run that and see what we come up with. And they it is, we have the following elements. We have Toyota, we have Ford, we have, we have bands, right? So in essence, what we've said here is we've used this technique of this length property to be able to print out everything that is in there as long as it does not exceed its own self, as long as it doesn't get out of its array list, then this should keep on happening. Right? Then, on the other hand, we could also just talk about how to use R at, how to look through, um, through an array with four each, with a for each statement, if you want to write the for each loop, if you want, right. The syntax for this definitely occurs in the following manner. We just simply do this. We could say for with lower caps off cancel four. Then we write the type of whatever variable that we're working with. And then there's a variable over here. And then we just stay the array name, array name as well. Right here, no space in between. And we open up whatever it is that we want to be dealing with. You see that? Obviously we won't have to close it as well. So an example of this would be asked doing what, for instance, still using exactly the same thing. Let me just put them in Commons. Put this in common. Right? So let me just take this, all of it. We definitely are gonna be using it right here again. So let's say we have the same string of costs over here. So what we could say is we could say for this train I with being the syntax of costs with causing there as well. And also opening up our brackets, we have system dot out, dot, print LN, print LN. Then we can just print out i, for example. We can just print out I just like that. Then we try to run it. And let's see what we get. We come up with the same thing, right? So it's really just a method of, you could say I'm a matter of technique if you want. You can definitely use them as freely as you want to use them really, It's just a matter of technique and preference on how you prefer your code to look like. Then the next thing that we're going to look at, let me just put this in Commons. The next thing that we're definitely looking into is called Java multi dimensional dimensional, multi-dimensional array. Java multi-dimensional array, right? And for this one, you just need to bear in mind that in order to create a two-dimensional array, you need to add each array within its own set of curly braces. Syntax of this would be something like int. And then let me just take this braces as well here. Let me just do this. Great. Yeah. My num bus for example. Then we say, we equate it and then put this in its own braces. So just be very cautious of this will have two events, be 1234. So there's four over here. We'll stop right here at four. So let me just copy this guy and paste them right here. And then we say coma because we are still continuing. And we open up. And then you say 567 for example. And then we close it up like that. And not only once but actually twice. And then we lock it like that, right. So this is an example of it. If I were to take it out of your comments just so that you can see if it's recognized by java. Let, let, let me just try and do that and you can check it out for yourself. So here it is, Here it is right here. And we have end over here. And our braces here, A2, B2. That's why we're having an arrow over there. So there they are. Each one, you could say each one represents its own thing and see that this one represents this one. This one here represents this one right here. You see that? So that's the syntax essentially. That's the syntax essentially. 12. Multidimensional Arrays: So it's just worth noting that now that it's in this fashion, it means that this mine numbers here is now an array with two arrays as its elements, right? To access the elements of my numbers array, you need to specify two indexes, one for the array and one for the element inside the array. So the example I could give you for this would be something like this. For example, let's say we use exactly the same thing that we've used here. And then we were to say int x equals two my numbers. And I were to say, for example, one. Let me try and just copy this so that I can be much, much faster. Do I want to put it in this question? Rather, I'm going to copy this is what I want. This is what I am because I need to specify off. The first one I'm specifying is the array. And then the second one that I'm specifying is the position in the array. You see that the array and then the position in the array, it's self. So let's say I were to specify something like 12. Yeah. So by specifying 12, what's actually going on here? What am I? What am I actually saying here, right? So by specifying one here, this is the one that this first brace here, or rather square here, contains information telling us about which, in which area are we in, are we in array 0? Remember, this is array an array 0. Remember this is our a 0, or we are in array one. You see that? So this is our a 0, this is already one. This is as far as this is concerned. The second square over here contains information as to now that we're in that array. Which position exactly are we referring to to extract our element from the sea? 13. For Loop: So we, we just continue like this and say system dot out, dot, print n. And we print out the value of x because it's just evaluate, it's just one value out of that, just verifying that we don't have anything else up there. And we printed out here. Therefore, we predict if I sell 12, it means 01. We predict ourselves to be in here. Position two per centroid is 012. We predict it to give us a value of seven. So let's run it and see seven day it is beautiful. That is, so it's seven over there. And we can also use a for loop inside another for loop to get the elements of a two-dimensional array. And of course, we still have to point out to the 2x's indices rather. Definitely still need to do that. An example of that would be, let's say using for-loop, using follow-up, right? So an example of this would probably be, would have to specify and create a method here and say, call it public. I just want to verify what method we're in. We're in public static void already. So that's good already. Except that what we're gonna do is we're going to come all the way down here again. And just, we don't need to specify the method because we already have it up there. So it's just going to be end. And we copy our end here again. And instead of even writing all this, I could just copy this really. Let me just copied and pasted right there and say my numbers. And instead of just my numbers or put it as a one here, just to differentiate it from the previous scenario that we had. And what I'll do as well is I will just say for int I is equals to 0, I is less than my number one, right? Because this is the particular one that I'm actually referring to. Their length. Remember that length? It's meant just like that. It's with the length. And then we make an increment of I. So there it is. We have an increment of Iowa. And we open up our for loop over here. Then we add another for loop right in here. And we say for int j is equals to starting from 0 as well. And saying 0 rather non-zero. I prefer using j non-zero. My numbers again, dot length. Not really done. Dot length. Let me just place it like this instead. Let's go back. And I'll just take this here minus two squares here and place them here. So I have my two, my square, just one of them and please my eye right in there. And that's the length that I'm looking for. That's the length that I'm looking for. And just keep on going up with j really, keep on going up with j really. And for each of these scenarios, I need to be printing out values here. And in particular, printing out here my numbers and just having them in terms of I and j, normally it should work like this. So let's just run it and see what we get from that and just better understand what's going on here, right? So it's really just a situation whereby we're trying to deduct or come up with all these values from here. So we have an int and then we save for end, whereby it's because essentially what am I saying? I'm saying, as long as i, which represents the area mean, Remember array 0, array one. As long as this is less than its own length, which is, it has a length of one from 0 to one, right? So it means it will take the first 0 and come here. Because 0 is allowed here, it's definitely less than one. Then it will come here and print out what's going on here. Print out what's going on here. In fact, the length here, urbane mind It's actually two because it's the length of this, it's 12. So it will take 0, check it, and see that 0 is definitely less than two. And move on to say that what about j? J is equals to 0. And then say j is less than, j is less than three, as you can see there. For j, how many elements? They in day in the first place. So for j, in fact, it's not three elements. It's gonna be 1234567. So it's going to be seven elements in there. So it's going to just take and store that value of 0. So let me just put a comment here just so that you can see it better. So it will take, as I said, just take the value of 0. Firstly, we will have a 0, right? Then against that 0, it will run it and take another 0, right? And then it will come. And let me just copy this. Print out the value that is corresponding to that and 0 comma 0. Obviously that's gonna give us one. Then it will come and it will cause an increase way. It will cause an increase as far as J is consent, right? So it will just cause an increase wages consent, so it will be 01. And therefore 01, as you can see, it's 0, it's in this array, one, it means true here, so it's gonna be two. And then we come over here, we say, What about three? Here? It will now be two, which here will make it three, as we can see it over here, and so on and so forth. I can probably assumed that you already seen a bit of a pattern here that's definitely emerging. So let me just change those values for us. So it's going to be three here, it's going to be four here. It's going to be four here, it's going to be five here. Then here it's gonna be five here, leading to six here. And then here it's going to be six here, leading to seven here. Now why will it eventually, and by the way, when it gets up to let me see 0123 here, normally here it's going to change. It's going to be rather one. And then, because it's now in this set, and then it will look for the position here and start again from 0, right? So it's going to be like that. And then here it's going to be one. And then here it's going to be again one. Then here it's going to be now one, and then here it's now going to be two, right? So essentially this is what will then eventually give us all these values. If you were to try and locate them yourself, we will need a pen or a pencil and paper. And try to locate 00. You'll see that it's one 01, it's 2023034105116127. You see that? So essentially that's how it's actually making sense of what's going on. Right, right here, right, right, right here, right? So what we're gonna do next is we're just going to move on to the next area, move on to the next thing really. 14. Methods: Alright, so the next thing that would definitely going to look into is, has got to do with Java methods. Probably the most important thing that you will come across when you do Java. And to properly understand this one we're going to define freshwater method is a method simply is a method is just a block of chain. This block of chain, or a block of code which only runs when cold, right? So you call it, then you can definitely make use of it. So you can pass data known as parameters to a method. And methods are used to perform certain actions and they also known as functions, right? Right. Yeah. And why would we want to use methods? You're probably asking why. Well, truth is, it's just to reuse code, really. Reuse code. Define the code once. And you will use it as many times as you want. As many times as you want. Alright? So that's it, right? And the key thing that you probably are wondering now is therefore, how do we create a method? In order for a metal to be created, it has to be firstly declared within a class. And it is defined with the name of the method, followed by the parenthesis, of course. And of course, java will provide some predefined methods such as system.out.print, line as you know. And, but you can also create your own method to perform certain actions. An example of this would be, let's say you wanted to create a method inside main. So what you do is you'd just say, let's see, let's go all the way up here and just put everything here on the comments because we don't need it. Right, right, right here. In our public class, we'll just, instead of even making it public, will just make it a static class of the following manner and then call it, call it. Let's call it myMethod. It's easier to just call it like that MyMathLab main method. And my method, that's what it is. It's just our own method, right? And with this, our own method, what I'm going to do is I need this cos let me put this guy right here. Make sure that everything is under comments and that there are no errors we collecting here, especially here. And here. We don't need any of that, Right? Right. Excellent. So now that we have it in this form, we'll just call it our method. And then literally here we could have pulled to be executed, right? This is what we need to execute. So an example of this would be, let's say that you wanted to write something overflowing nature. For example, let's say that you wanted to say, hey, system dot out, dot print LN. And then you were to say, Hey, This is fun. This is one, right? So he went on to say that. Then let me just decrease this distance here. I usually prefer them like this so that I can know what exactly I am doing right? Then I could alternatively just pub, public, static, void, main, and define my string over here. My string right there. Let me just, I need some squares or get them from here. And get my squares over here and put my string like that. And I'm just like this, I will just call this a RGS. You can always put this in front or behind. It's not a big deal really. Define whatever it is that I'm trying to execute. So I'll say. Mymethod end. Here. As you can see, Java actually recognizes that I can run this, and when I run it, it should just say, this is one. This is one. Why is that Swedes were running this and it's essentially just, it has understood that this is a method. When I call up on this, I'm calling upon this to be done, right? So imagine I were to just do this and place this here plus this, plus this, plus this here. And it's like literally using the same thing again and again and again. So each time it will just call again. This is one, this one, this one doesn't. So I can use it as many times as I want. And obviously this is a very Lee example, but it just helps to prove to you that a method can be called multiple times with no problem at all, right? Which comes in very handy. More further we go in the whole aspect of methods and all you see. So just information can be passed. Two methods as parameters, and parameters act as variables inside the method really. And parameters are specified after the method name and inside the parentheses. And you can add as many parameters as you want. Just separate them with a comma. That's the key thing really. And then this example that I'm about to show you has a method that takes a string called I'm F9 as a parameter. For example, when the method is called, we pass along a first-name which is used inside a method to print out the full name. So let's go right into it and see it ourselves, right? So let's say that we have public static void, and then we have a string here. We call it fname, like I just said, F name literally just means first-name, right? Then here we'll just say fname. We're calling it again. And plus Reference runs. When I do that, I can come over to my public static void over here. And now still specify it because I should specify what's going on, what happened in here. So I need to give names, for example, tom, Tom in there. But remember Tom is a string. So I should have it. Tom as a string. And there it is, It's already identifying him as a string. And then in here as well, Lindy. Lindy, yeah. Then in here I have Sam. And then in here I have Rob. And then in here I have Lincoln. And yeah. So if I run this and let's say that this is a mean, literally mentioning all this for one family. So let me say it's a family of Thompson's Thompson's sending. I have therefore Tom Thompson, Linda Thompson's, Sam's, Thompson's, Rob Thompson's and lick on Thomson's. Now you're probably saying, hey, what I wanted to add space between them, no problem. You can always just do that by putting, by putting this right here. And when you do that, it should have a bit of some space between them. Let me put it like that. And voila here. Tom Thompson was Linda Thompson. And sometimes it's all one family if you want one big family. Alright? So just bear in mind that when a parameter is passed to the method, it is called an argument. So from the example that I've just given you here, fname is a parameter, while this name's Tom Lindy, Sam Rob Lincoln, or arguments, you see that they're just arguments. Got the same really even in mathematics, whatever is in the parenthesis, we call it an argument. And just bear in mind that you can have as many parameters as you want. And just say that for each of them, I had wanted to specify as well that hey, I want to know their ages so I could even put age here. And for once I do this, I need to put a comma and say Tom is 12. For example. Lind is the oldest one. She is 28. Sam is 20. Rob is somewhere in-between 25. And Lincoln is just for yeah. So if I run this, it's now going to as well show their ages. Alright. It's now going to as well show the ages. Now as you can see, it's not yet showing that a is why is that? Why is that? It's because I did not specify here that, Hey. I also want the agents, right? So let me just say this plus, plus and H days age. So I could even say maybe add a string that says something like the data is. Then I say that h, So let's run it. There it is. Tom Thompson's installed. Then this is tall, 828 sentences is 20. Rob Thompson's is a 25, and Lincoln Thompson's is four years old. So that's the beauty of it. And you just need to bear in mind that when you are working with multiple parameters, the method coal must have the same number of arguments as they are parameters. The arguments must be passed in the same order. So we could also have some return values. So just bear in mind that when we talk about return values here, we use the void keyboard, we use it in, we've used it in the examples above. It indicates that the method should not return a value. If you want the method to return a value, you can use a primitive data type such as an end or a shower instead of void, and use the return keyword inside the MathLab, Right? An example of this would be, Let's say that we have something like this. Let me see. Let's put this in comments here. We don't need this one. So instead of static void, what I'll do is I'll just say static int. You see that? So when I say static int, it means I'm very sure that I want to work with ints if you know what I mean. So I can just do this and just say int age. And here in so doing, what I'm actually saying is that I'm saying that, Hey, I also want you to return my age. Alright? So I want you to return age. Could even say age plus a number of example is plus seven. And it can, it can definitely work. And then I definitely will not be needing this for now. So let me remove it. And then when it comes to the static, remove that mistake. Yeah, when it comes to this void over here, what I'm gonna do is I'm going to say system dot out, dot print. And I'm going to print out my method of age. And I give my value of age, I give it as five for example. And by giving it five, it means when it will detect that all ages five and it's going to say five plus seven and get, any artist should get 12th normally, it should get 12, normally. Beautiful. So there it is. It's gotten 12, right? This example definitely returns the sum of the methods, two parameters. You can be as creative as you want really in definitely working around this. And just a more elaborate example of this would be what if I had said and why as well is also there? Rather not just in age, let me call it H1 and H2. Be more practical. Age two should make sense. Now. H1 and H2, H1 is then too rather, let me put it as H12. But what does just as two really, that's, that's really all that I need. And by essentially doing this, what I'm doing is I'm saying return is one plus j2, for example, which should be five plus two, which should be a seven. So let's see what we get. We get a seven. I could still even add a value, seven plus three, which should be a ten now. So there we go, it ten now, right? So that's, that's really how we really are able to make use of the two parameters. Yeah, you can also just store the result in a variable, which is recommended of course, as it is easier to read and maintain, its easier to read and maintain. So just a more elaborate example of this that I'm talking about would be, let's say that you had, for example, x here and y here and the shortest and the most, the ones that we love the most when we talk about mathematics is y here, and there's an x over here. And what we wanna do is we can just simply specify when a z here if we want and z here we'll call it our method. And call up on 54. Then we just print out z. Right, isn't only to print out all of those things that will printing in the first place where all we want to do is now we can just print out z. And let me just close this properly as well here. And my dad. Yeah. So it should work right away here. So let's see. It should be without my method will just say x0, really, that's all we need. So we'll just run it and we get nine, that's four plus five, which should just be simply nine. So that's that's the other value to it right there. The other venue definitely to it. Right? Right. So the next one that we're definitely dealing with is what we call the Java method overload. Alright? So the Java method overload works like this. With overloading, you can have multiple methods that can have the same name with different parameters, right? Example of this would be maybe if I were to say something like, hey, what if I have an end? My method? Rather let me call it med, one is equals to, not equals to or rather just met one. And then I say int x. And yeah, instead of using x, maybe I've used it too many times into T is better. I think entities, but definitely I could also have a float and just call it mad too. And I'm colored float are and have double as well. Mad three with a double inside of calls. An a and a double of B. Yeah, definitely, this should definitely be though, where we can now also do it. What we can do is we can have an example of this. An example of this would be, let me just get rid of this because there are some things in there that I want to clarify and better with an example. So let's do it. Let's say that. Let's come back to our static method over here. And we say is that the end plus. Let's call it a plus method. Then with this plus method, what we have is we have int x and y definitely, and we return x plus y. And then we say static, static, double, static double. So we have a static double Plus Math PFAD with double over here. And this is with an int here. Very important. Here it's doubled in here, in the brackets. I'm going to put my two doubles and call it a double x, double y. And just have this return x plus y. Again, right? And just have that public static. Let me remove all of that. I don't need it. Just come back into saying Let me just make sure that this is where it belongs. Yeah. Yeah. So we could have right here public static method that we always use public static, void main. And have this train. And on top of that string we will have our squares as well. So let me just get them. As you know, with my keyboard. I have to get them all the way down. Like here. Definitely here. So we get them string and RGS. So right there, we open this up and opening it up. What do we say? We say int num. For example. My num one is equals to a plus method. And we please venues like seven comma nine for example. Why not? Then we move on to say double. And we say my num two, which is equivalent to plus method double. And here we're going to just put something that is a bit of a fraction, maybe five-point, let's see, maybe 5.4 with 6.9 for example. That. And then we'll just say a system dot out dot print LN. And what we want is we want to print our integer venue like that with a string that is, and just plays all our r value that we want to print out here, which is going to be plus num one. Right? Then we're gonna do a similar thing right here says system dot out, dot print LN. And right in here, we're going to have a double in a string format with alarm, alarm num two over there, right? So let's run it and see what we get. Normally it should give us sums of those two values. Here. It's going to be seven plus nine, which is 16. And a double here is going to give us, let me just put this as well so that it's relevant. A double here is going to give us 5.4 plus six by nine, which would be just 12.3. Alright? So definitely this is how we can make use of overloading if you want. Alright. 15. Scope: Alright guys, so the next thing that we definitely want to look into is what we call the Java scope, right? So there it is, Java scope. And whenever we talk about the Java scope, essentially what we're talking about really is just the region that is accessible, right? That's where variables are found, right? So let me write it down. We're talking about something of the following nature. In Java, we know that variables themselves only accessible, only accessible inside, rather inside a region. They are created. Let me make sure I put that right side of the region. Created is a double S over Matt said originally created. And that itself is what we call the scope. This is our scope. So that region that, that makes them available, That's the scope essentially, right? So variables can be declared directly inside a method, and therefore can be available anywhere in the method following the line of code in which the way declared. An example of this would be literally what I have written right here. I just have a look at what we were doing here with our previous method. So we have a public class main, then we have a method over here. We call it maybe, let me talk about this one, especially static double plus method double and then we have that and then over here we have the interest in one. Let's put our focus right here. Focus here. We have public static, void main, right? Then in there, what do we have? We have we put whatever you want to put in there. Right. And it's therefore accessible. All even whatever we declared out there, if it's able to be called for in here, right? And if that doesn't make sense, I can always just do this for you just to further clarify what it is that we're talking about. Can think of it like like this. Let me just clear out all of this. We don't need this anymore really. All the way until right here and delete. And let's just go directly and say public. Not upper cap, a cap, a public static void. In fact, I should just delete the whole thing, rather just remove this top part here. All of that. Yeah, that's what I don't need and I don't need that. But this I need absolutely just to prove my point over here of what I'm talking about. And therefore, what are we saying here? We're saying that we could have something like this end here. The code that can be here cannot use x, right? That's the area. That's how we have defined it. And then we could then specify that integer of x is equivalent to 100, right? And with that, we can say, we can create something that can use X. Code here can use x. And we call for that code that can use x or we say a system dot out dot print LN and then recall, and we print out x. In this case here we had nothing, We have not been declared. What exit solve means, you see, so we needed to call it first and declare that variable of x and therefore be able to then call up on it and print it out. So if we were to run this now, it should be able to just give us what x essentially is, right? And what I'll do is just to ensure that everything is well, let me just put that down here and put it right here. Beautiful. So let me just run that for you and see for yourself what we get out of this. So we're currently running it. And a 100. That's because x, we've declared x as a 100. And this is just a method scope that we're still doing right here, right there in something as well called Block Scope. And a block scope, you can think of it more like this, right? So a block of code refers to all of the code between the curly braces, this other color braces we're talking about. So anything that's found in-between these two colored braces, this and this right here is just a block of code, right? Now, variables declared inside a block of code only accessible by the code between the curly braces, which follows the line in which the variable was declared. To elaborate much further, let's, let's make an example. Let's say right here with the same example that we have here. Let's say we do something like this. Let's say we were to, instead of having x right here, Let's say that we were to do something like this here we know that a code here can not use x definitely. But then what if I were to do something of the following kind to say and put curly braces over, then open the site. So you notice whatever that is in-between these two curly braces right here would be a block. This is a block of code. Whatever I put in there would just be a block of code. And that block of code right there. It can not use x as well. Light cannot use x as well. Can not use x. Nevertheless, if we were to, for example, just specify and say x is equals to a 100. Again, maybe nothing special about a 100, just like using it. We can see that the next code that we implement can definitely take consideration of what access code here can use x. And like that, we can just call up on it and it's a system dot out, dot print LN X. There is no error as we can see. Then we see therefore that this block of code ends right here. Let me just do this. Roller. So the is equal n right here. Put a blog and here. Then the code here as well that will be outside of the curly braces. Code here, can not use x. So you see that, You see that effect that it's within this curly braces allows you to access x. But the moment it comes out, you cannot access any x anymore and datas, we have our 100 over there that we've just specified, right? So essentially that really is it about block scope and bear in mind that block of code may exist on its own or it can belong to an FYI of false statement. In the case for any case off. For statements just bear in mind that variables declared in the statement itself also available inside the block scope. It's just something else that you want to keep in mind whenever you're doing your coding, right? Alright, so the next thing that I want us to focus on is what is called and all of this. Let me just delete it. We don't need it. The next thing we want to talk about is what we call Java recursions. Write Java recursion. So let me just put it down for us right here. Let me just do those. Yeah, java. Sometimes when you hold shift for awhile, this is what happens. Java recursions. Awesome. So what is a recursion? Recursion inherently is, is just the technique of making IF function call itself. So if you have a function that keeps on calling itself, then what you've just done over there is what we call a recursion, right? So there it is, call itself. This technique definitely provides a way to break complicated problems down into simple problems which are easier to solve. And of course this might be a bit difficult to understand, but the best way to figure it out as always, just encoding, you've got to do it. You've got to get your hands dirty and just do it yourself. You see that? So let's just check out this example over here. Let's say we want to use, use recursion to add all the numbers. Up to ten. Want to add all numbers? Well, one thing is proper English word here. All numbers. Up to ten, right? So how would you do this? Well, you probably want to start first of all by just declaring what method you're going to use. So we're going to use static, void, main, and call string. Here, ARG is here. And right with our string over there. What we wanna do is just wanna use the squares right here. So let me just call them that. And get back here and change my keyboard back into its normal default mode. And then int result definitely within our block of code that is, and we say sum of ten. That's what we're looking into some often. And shortly we are going to define what the sum of ten is all about. What does that mean? What should Java understand by taking into consideration whatever is called the sum of ten, right? So we print the result here. Then what we wanna do is, right after taking this out like that, we want to create another method here, the one that's going to define what some itself means. So we'll say int sum. And then we'll just call up on the integer value of k. Yeah, so there it is. Now we recognize it. So Java is able to interpret and say, oh, okay, so the value of some, there's a method that is able to call up on the sun. So it's yet to understand what that method actually saves and how it should behave, right? Alright? And then we just say if k, if k is greater than 0, what should happen is the following. We should return k and add the sum because we want it to be recursive k minus one. Yeah, so that's where the recursive ability comes in. And I'm gonna interpreted this over you just sorted, you can now thoroughly understand what exactly is going on here. Otherwise, should do this. Meaning of the condition is being as not being met, just simply return the value of 0. And that's about it. That's really about it. That's about it. Let me just do this so that I can always get us lost over here. This guy, I'm going to take them and drag them and put them all the way here. Just so that you remember this guy down, down, down here. Sims, there's a bit of an error somewhere here in this block of a block of code that we've been dealing with. Yeah, just do that. All of the error is gone. Alright, so essentially what are we saying here? What we're saying essentially here, and I'm just going to put a bit of some commentary here just so that you can better understand what's going on. We're adding up values and by the way, let's run it faster. We can see if it works or not, and then we can now move on to the next thing. So there we have it. It's 55-year. You can always do that yourself. Just try and says 0 plus one plus two plus three plus four plus five plus six plus seven plus eight plus nine plus ten, you get 55. Now how does this occur actually? Well, what's going to happen is this. I'm going to take our value, our result value here. And normally about this, it's a class obviously. And then what Java is gonna do is gonna check for the value of the result, the sum and say, Oh, the sum is eviction is actually a value of ten. And then say, what does this method of some do? 16. Halting Conditions: How does it do actually? So it will just come over here and try and understand what Sam is all about. And it will register a value of ten here, right? Because we have chosen it to be ten and then say ten is greater than 0. Is that true? And then you say, Yeah, that's true. If that's the case, then return k, which in our case is ten. So it will return the value of ten. And then plus the sum of k minus one. In our case, k is ten. So ten, essentially it's 1010 minus one. Essentially that's what's going to happen, right? And what is ten minus one? That is actually nine. So essentially we're talking about the sum of mine, some of mine. And it's going to take that same value of nine. Take it all the way back. And we're still in this loop. We're not coming out yet. So it's gonna go up here and say, nine is greater than, is nine greater than x4 and say, yeah, that's true. So we tend to value of nine, see that? Essentially it will just give you, now it's no longer a sum over there. It's just gonna be the value of nine itself. Plus the sum of, it's going to be nine minus one, which is the sum of eight. See that? With the sum of eight, the same thing is going to happen. It's going to go over against the eight is greater than 0 and then return the value of eight. So now we have the value of eight itself. Not a, not a method of eight, but its a value of eight itself. And then it will say sum of seven. Then the same process keeps on happening. And this is what makes recursive. Remember, repression by nature is repeating a function that keeps on calling itself. That's what we're doing here. We're making this function of some coupon calling itself again and again and again and again. So it will keep on doing that. And it means we'll have plus seven plus six, plus five, plus four, plus three plus two. I'm going to space them out plus one, right? And then when it gets to one, what is it going to say? It's essentially just going to say one is greater than 0. Is that true? Return one plus sum of one minus one, It's 0, right? So it's going to say plus sum of 0 right here. The sum of zeros. Then what it's gonna do is gonna take the sum of 0, say the value of k that's now defined as 0. So you will say 0 is greater than 0 and we realized that's not true. That's false. And salt, because this is, this condition is no longer being met, it will now skip. Skip this conditional statement and come here and say else we tend 0, which is true. So it will just end up just adding an additional 0. You see that? So as you can see, that they keep on adding together. So here it will just say ten plus 919 plus eight. Thirty-seven, fifty four. And like actually, it's going to be 19, 27 for 40, forty five, forty nine, fifty to 5455. You see that? So that's how it keeps on summing up on this values themselves. You will add them. It won't be recording them. I'm just recording them like this for your sake. But what it will do actually is that each time it will keep on doing and doing something like ten plus nine indents in 19 and then send 19 plus eight. And then give you, like I said, 2727 plus seven. And then it will give you 34. And then it will add a 34 plus six, and we give it 4040 plus five. Give it 45, and then it will say 45 plus four, and then it will give it 49 and then 4949 plus three. And it will give it 5252 plus two. And we give it 54. And it will say five to four plus one will give it 55. See that? So that's how it's mounting up and actually grow into a final value of 55, right? So just bear in mind that when the SUM function is called, it adds the parameter k to the sum of all numbers smaller than k and returns the result. So when K becomes 0, the function just returns 0 when running in the program follows the steps that I've just shown you right above, here, right? So of course there could just be a bit more creative and maybe even give like a halting condition, a stopping condition of when it should know when to stop, under which circumstances under which scenario shouldn't stop. Talking about that, talking about the Halting condition. Halting condition. When you talk about this, we know that just as loops can run into a problem of infinite looping, recursive functions can run kill a problem of infinite recursions if the stopping condition isn't properly stated rate. So hence, why we need to learn about the heart and conditional the stopping condition as I like saying, I'm going to just put this force here on this way and just put it like that. Right? Awesome. Great. Okay, it's okay now, so we took him about the Halting condition and infinite recursion or cares, or rather it's when the function never stops calling itself. Just put the dead. Infinite recursion is when a function never stops calling itself. Right? Every recursive function should have the Halting condition, which is the condition where the function stops calling itself. In the previous example. For example, the Holton condition is when the parameter k, as we saw, when k became 0, that was, that was how Java had to know that, oh, we stopped right here, right? So it's helpful to see a variety of different examples to better understand the concept. And in this example, the function adds a range of numbers between a start and an end. So the hot end condition for this Lucas's function is when n is not greater than stat, right? So we're going to make an example here and just try to see if we can use regression. So we're going to use recursion and we'll put it down for us. We concussion to add want all numbers between 510. So all numbers between 510. So we're going to do that and just see how our whole thing evolves. So we're gonna go back here, right, right here, and just modify the same thing that we've been using. So just the end result. And then for some here we're going to make it a bit interesting instead of just saying ten. Since we want it to start from five, I'm going to say 510. Yeah. So it gets to be red because as far as the method of some had already been defined, it had only one parameter in there, so it's a bit confused as to what's actually happening here. So we're going to change it when this permanent itself. We're going to have a starting permanent of int and then ending Paramount of India right here. Now it's okay because we've defined it as two parameters which have been recognized as five as a start and tendons the end. And bear in mind that decides just names of variables for me to know that this one is starting the others endings. Because studying and have particular functions that are Java is able to recognize that starting in means a sudden endosome know, I just called them that way. I could have called them x, y, z, whatever I want, right? But what I'm gonna do is that I'm going to say if, if the end is greater than my start, just like we had done on a previous case. The end is greater than my start. Then what I want to do is that I want to return the end and have my stat do following. It's gonna be start and end minus one. So it's going to keep on doing this over and over and over and over again. And then it should return the end. Now, literally almost like the other question that we were just doing. If you pay attention, you are able to see that it really is almost like what we've just done a few minutes ago. And so we're going to go on and run it and just see what's going to come off it. And there we have it. We have valley over there of I believe that should be what? Forty-five. Is that it? Yeah. I think it's 45. So that just tells you that one plus two plus three plus four are simply just do what? They add up to ten because it's the difference between the other. But five plus six plus seven plus eight plus nine. Up to ten, it genuinely gives you just what? It gives you 45 itself, right? So there we have it amazing people than we have it. 17. Object-Oriented Programming: Alright, so the next thing that we want to look into is what is called. And this is probably one of the core things that we definitely want to know in Java. It's Java, OOP, object-oriented programming, right? And that's what all P stands for. O P essentially just means object. Down for you. The object oriented programming. This is something you're going to come in contact with a lot of times. So just bear in mind that procedure or programming is about writing procedures or methods that perform operations on the data. While object oriented programming is about creating, creating objects that contain both data and methods. But open type over that, both data and methods, right? So object-oriented, there's a hyphen nominee over that. Object oriented programming has several advantages over procedural programming, right? So those advantages are advantages of 00 p over procedure. All programming. Role programming. First one is o p is faster really in the hole. It's able to be fastly done and executed as well. And so that's the definite and wind at you want to do if you are working on deadlines and all. And another thing is that all P in simply provides clear structure for problems for programs. So there's a clear structure for programs. And also OOP, helps to keep the Java code dry. And by dry, what we mean is you don't have to repeat yourself. Don't repeat. That's what drives you solve. Let me just write that down properly so that we have it. You don't have to repeat yourself. And therefore makes the code easier to maintain and modify if you want to. And of course, debug because there's code. Especially according a lot of things you find the bugs eventually come into the code and you want to have the value of all p's that it allows you to easily, without much of a hustle, really debug or removed bugs from your code and all p as well. And makes it possible to create reusable, reusable applications with less code and shorter development time. That's the beauty of t right there. That's the beauty of it, right? So just bear in mind that the DRY principle or the don't repeat yourself principle is about reducing the repetition of code. You should extract out the calls that are common for the application, then place them at a single place and reuse them instead of putting it. You see that? So that's the beauty of object-oriented programming right there. When we talk about O P, we cannot talk about, we cannot talk about OOP without talking about some understanding or a thorough understanding of classes and objects. But it's the difference between those two and what exactly adults. Just understand that clusters themselves, essentially an objects rather than the two main aspects of object oriented programming. Classes and objects are two main aspects of o p. And you can think of a class really like a cluster of foods, for example, fruits. The objects of this class will be what? The objects will be. The different fruits in there. You see that we could have an apple. You could have a mango, you could have a pair. You could have a banana. It could be all these things. You can think of a class really more like something that's containing other things inside of it. More like what you've been hearing seeing here is a cluster and then inside the class we have different objects that we can talk about. You see that all the class of the same class, you see that. Another example would probably be a class of cars. Class of cars. And inside of cars, we can talk about Volvo, we can talk about bends. We could talk about how Honda, yeah, on the end, Audi, right? So they're all costs at the end of the day, but the class is the thing that contains them row. So you can think of the class as a template for objects and an object as an instance of a class. Alright? That's the term that you'll be hearing a lot instance of a class weight. So that's important. And then when the individual objects are created, they inherit all the variables and methods from the class. And we'll definitely come into this a bit later on in more depth. But for now, that's just about it for now. Alright, so the next thing that I want us to look into is what we call the Java classes and objects. I mean, we're already begun them a bit over here, but we're just going to delve into them a bit more now. So knowing that Java itself is an object-oriented programming language, everything in Java is associated with classes and objects along with its attributes and methods. For example, in real life, Kaizen object, the chi has attributes such as weight, color, and methods such as Dr and break almost a surf methods or C. So a class is an object constructor or a blueprint for creating objects, right? So in order to create a class, we usually use, we use what? We use the keyword class. So an example of this would probably be something like something like this. For example, I could say public. This is just a bit over. Just for you to understand how you do it. Public class, as you've seen us do at many times. May. Then, obviously we're going to have this curly braces here. No one could say x is equals to phi, right? So that's just something that we've been seeing so many times. He usually did have already does this for you most times. But then as you advance their scenarios where you might want to do this yourself. But for now this is, this is all that you might need. This is okay for now, makes sense. And obviously we're going to have a breeze here to close it. But just because it's an example, I will not go this far to show that, right? But then in order to create this as to creating a class, it's really this. What about creating an object? And object? What to create an object? What we wanna do this. In Java, we need to start off firstly, an unordered and in Java, an object is created from a class. We have already created the class named main here. That's the name of the class, It's called main. So now we can use this to create objects. To create an object of main, specify the class name followed by the object name, and use the keyword. New. Example would be exactly right here in the same class here, Let's say that we were to create an object into say, public static, void, main, we're stating will recruit in this object string. And I'm going to just take this part right here. Literally the same thing that we want. String. And then we are just going to say in main and colon object my object. So calling a method here and we're taking all our object and we say new, may see new main and right there we also say system dot out, dot print LN. And then we just seen my all and close that. Then we could have been subtracted from x if we weren't really consuming. You already had a value of x over there. And we can run that. You see. So let me just exactly copy and paste exactly what we've done here. And let's put it right here. Not in the comments anymore, but in actual thing that will still running at the moment. So let's say close it up here. So here we already have a class already, so we don't need to do that again. Then let's see, here we already have a public static void done for us, so we don't need to do it again. We can just literally take the same thing here and just place it down there. And console this console bad. Alright. And we can take this, put it above here, because it's an online class, the general one. And we already have everything in place. Alright, so here the challenges that Bain mind that we have our class name as Hello World, right? Since our class, namely, we already stated it as Hello. Hello World, what we're gonna do is we're just going to call it the world. And when he as well, Hello World, That's the default name that we have over here. Of what we're talking about. This is small m, my OB gene. And it's gonna read x. It's not minus. 18. Class & Objects: Alright, so the next thing that we want to look into is just really focusing more on the Java class and objects, right? So we're just going to focus more on that, especially. And just bear in mind that Java, being an object-oriented programming language, everything that we do in Java is associated with either these two things here in the class or an object, along with its attributes and methods. So for example, in real life, a car is an object and the chi is what? It has, attributes such as weight and color. And methods such as Dr and break. You can think of methods as acts. What to do. You see that? Attributes as what you look like. You see that can I describe the right? So I plus is like an object constructor or a blueprint for creating objects. So for us to create a class, really all we need is just simply to state something like this and say public class HelloWorld, right? So we already have named by the of all class years hello world. Usually Java would do that for you, but there may be scenarios where maybe you might not, you might want to do that yourself. But for now it's okay. And then we could even say x is equals to five for example. And, um, yeah, that could definitely work. And then if we want to maybe create an object that was the initial one was as creating a class. But this one, we want to create an object. In order to create an object, you have to bear in mind that in Java, an object is created from a class, and we've already created the class named HelloWorld force, as you can clearly see over here, right? So now we can use this to create objects. So to create an object of Hello World, what we're gonna do is we need to specify the class name followed by the name, and then use the keyword new. So an example of wood, this would be the following. Let's say public, static, void. Public static void. Let's try out and just say main string. Let me just change as quickly. Insert that, come back and ERGs. And right here, just hello world. My OBJ object, really abbreviation for objects, new, hello-world and voila. Then we could also just say, Hey, we want the sprint doubts or system of our print LN. And then we print out my OBJ dot x dot x. So whatever the object is multiplied by x really, right? So what do we come up with? Essentially, we come up with just five, right? So we get the value of five over there. And so there could be a scenario where maybe we want to create multiple objects of one class. And in order to do that, it's still gonna be very, very simple. Nothing complicated at all. What we wanna do is you just really is just we wanted to use say hello world, and then we now specify and say my OBJ. Let's say the first one was religious like one or just the beginning once or specified into two and just say new. Then we say hello world. And bear in mind that here we have object number to, object to that. Here we have object one. Object one, right? Then what we wanna do as well as maybe we could print out both of them really, why not? You could choose the same system. Dot out, dot, print. And then my OBJ, the first one. The second one because we already have the first one or with a. And then we just say by x, and normally we should have both of them come out. That is 55. So that's that's the beauty of it right there. That's the beauty of it right there. Essentially, we're telling it to print out whatever it finds in this class, especially the perimeter of X, as we have stated it right over there. There could be scenarios where maybe you need to. So yeah, I hope that definitely helps you out with that definitely helps you out. So the next thing that we want to look into is what is called Java's class attributes. Right? Here they are. In Java class attributes, attributes, what they do. And then in English, it's just something that defines the characteristics of something, right? In the previous scenario or less than we were talking about classes and objects. And even earlier on, we even defined what invariable means. So a variable is actually an attribute of a class that's really worth noting down. Variable is an attribute of the class. And so to give an example, Let's say we have a class called remove all of this. We have a class here, it's called Hello World for example. Therefore, with this in mind, Let's create attributes. So it will be x. And x is close to five, like we had before. We could even create another one into y is equals to seven, for example. So these two things, x and y, our two attributes, that's what they are we have been seeing up until now that there are variables. Now you're understanding that they're not just variables, but they are also attributes. That's what they are, that's what the, and. So another term for class attributes is fields. So instead of calling them attributes, you can always just call them fields as well. In order to access this attributes, you can access them by creating an object of the class and by using the dot syntax. This example that I'm about to show you now will help you create an object of our class with the name my OBJ as I've been using them, all my object. And we use the exact tribute and object to print its value. So just to even help you understand more what exactly I'm talking about, Let's just call up on public static, void, main, string. Just have this RGS and just loosen this memo. And yeah, let's have class HelloWorld and colon, our OBJ. Remember it doesn't necessarily have to be all. You can always call it something else. So we call on a new class now. Then we just print that out. You print it out. And let's see what we get out of that beautiful, that is beautiful, beautiful. So that's how we definitely access them attributes. Then we could also modify the attributes that we have already defined. An example would be, let's talk about the very one that I had done here. Let's say that I call on x, just x in the following minutes instead of five, I just say x and x. I could modify it right here and just say my object here, and just like that. But my object of x is equivalent to five. Let me just put it down. So it's equivalent to five day it is. And then I run my object of x. And I get five. If I change this to a 124, I should get 124 because I modified it. You see, initially it was just x. And have modified it right over there. Alright, if it was, for example, fall, we're here. Let's just run it and just try and understand. It still gets to be a 124. That's because the initial value it gets is really like we see for. But then it gets to this stage and says that all the new value of x that I should input, it should be a 124. Because it always takes up to Java, always takes the latest information given to it. That's the one that that overwrites the existing information. That's, that's, that's really what you can say about it. So I can just put the CN comment and say that x is now 124. That's what it is, right? So if you don't want the ability to override existing values, declare, you can always declare the attribute as a final example right here. You could say, if you don't want it to change at any stage, you could say a final x. So as you can see now is an error for me to change this. I'm not allowed to change it into anything. It then for itself, That's because it's not allowing for me to take any value. Not at all, nor, nor fresh input at all. I see. So I need to get rid of this and that's when everything will be okay. And if I were to print this, I should get the value of just for itself. So Betas that we haven't. Another scenario that you could possibly find yourself working with is just maybe working with multiple objects. And hard that happens is if you want to create multiple objects in one class, you can change the attribute values in one object without affecting the attribute values in the other. Example, if you want to change the value of extra 25 and object number two and leave x in object number one and changed. You could do something of the following nature. Let's say that they have this. We don't need the final one here for now. We have two objects, so let me create my second object. Second object being new hello-world and datas. And then my, my second object can be specified in the following manner. My OBJ dot x, it's 24, meaning that as far as the face value is concerned, it will just print out for as far as the second object is concerned, it will print out 24. So I'm going to print out both of them just so that we can better see. So copy and paste and just print both of them so that you can see the difference between the two. So the first one should be for the second interval. So there it is. Only the first one was changed. The second one, since it was modified. It has changed. You see that the first one remains the same, the second one changes. So that's what happens if you just want to have multiple objects in operation. You could also have multiple attributes in operation. So you can specify as many attributes as you want. And in order for you to do that, really it would involve you doing something overflowing nature. Let's say I were to remove all of this. And we're not talking about let me move this as well because I don't need it. Then let's say that I would say string firstName F9, given by Tom. Then I need to syntax as well, strain. This is my last name here. Sheppard from the game mass effect. So there it is. And then we talk about the age, and let's say he's 26 years old. And so what we're gonna do is we don't need anymore. Yeah, really, it's not important. So I could have and create my own object, right? As you probably have seen as too many times. Now, what I'll do is this though. What I'm gonna do is right here, I'm gonna just want us to print out something interesting. We're going to say just name, a name. And then with the name. We'll also go into just a colon or object dot F name, right? And then we're going to also call up on, alright, I give some space between them, not really collarbone. And then have our second object, which is our last name. L for L name and then I read delete that. And right here as well. What I'm gonna do is I'm just going to call on the age here so that we have the age. And we call that object and phone to the age right here. And let's run it and see what we get. When we do run it. There it is. We have named Tom shepherd, age 260. So this is definitely very valuable, very valuable, especially when you deal with stacks of code and just so much information that you need to process and just having it all have it altogether, have it altogether. This is some valuable information that you definitely want to keep in mind. Definitely want to keep in mind. Alright, so the next thing that we're definitely going to talk about is just called Java class methods, right? So from you've learned from Java methods chapter or whatever, the lesson that we're talking about, that methods are declared within a class, that they are used to perform certain actions. So in order for you to create a method, in order for you to create a method, you know that you, you definitely want to have the following. You want to perform the following actions, right? So let's say that I want to create a method, call my method. Yeah, let me just call it my method. So what I can do is I can just say static, void, my math forward, open that and open it like that. This is method. Yeah. Then write like that. Well, I don't need this guy anymore. Really. See, let me just drag this guy all the way up just so that we can always remember that everything is right there. So we've created an old method, really saw that a system that out dot print LN. Then we could say, hey, everybody, you want it. And let's see. Right, Okay, sure, there's a bit of an error here. Main method not found in class HelloWorld, this happens, please define main method public, static, void, main method, right? So essentially, yeah, It tells you that there's definitely a problem over here. So what we're gonna do is we're just going to say public, static, void, main. And we call on this train and just change our thing here and create those quotas and ARDS. And right here, we call on our method, my method. Now, let's run it and see what happens when we run it. Beautiful, that is myMethod, myMethod, right? So the error has been fixed and this is definitely how we deal with methyl. So whenever you call a method recruiting methods, you want to put them in their public static void and then run it in whatever method that is. It will show it will definitely function to your liking. That begs the question as to understanding the whole thing is here itself. The public obviously means that it's accessible to everybody, um, can be modified and changed in hardcover ways necessarily. But then static itself is a bit interesting. What does static mean? Well, static for us to come on to the topic of something being static or not being static, we need to really understand what's going on, right? So static versus non-static, that's what we're focusing on now. 19. Static Vs Non-Static: Alright, so we move on to the static and non-static natures of our Java programs. And you often see that in Java programs, we could have our geography. Java programs be either static or public in their attributes and methods, right? So in the previous example that we did over here, we created a static method, right? As you can see, there's a static method. This meant that it could only be accessed without creating an object of the class, unlike the public, which can only be accessed by objects, right? So let's have a look at the following example just to demonstrate the differences between static and public methods, right? So let me just delete all of this. We don't need it anymore. At least this part of it all the way to our public class over there, right? So right after public class, we're just going to name this and put it as a comment and stay static method. And our static method will be the following type will say static void and call it my static method. It's going to be much better like that. A bit of a typo over there. And then we just make sure that we have this in brackets. And we open it up like that. Then we'll say Just system dot out, dot print LN. And all we have to prove right up print here is just to say something like static methods can be called, can be called without creating objects. Without creating objects. Just like that, right? And then, on the other hand, are what we're going to do as well is that we're going to also just showed a difference here with a public method. I will put that as a, as a comment. And with our public method will just say public void, my public method. And just have this open up like that. And we just say system out, dot print LN. And then we just mentioned that public methods must be called by creating objects. So we need objects with public methods. That's essentially the difference between the two, right? That's essentially the difference between the two. Then what I'm gonna do is I'm just going to call this my, my main method if you want, right? This is my main method. The main one, right? So I'll just say something like public, static, void. Mean, as we always say. And then a right in our thing here, we're just going to call a string. And as you know, I need to get it over there because I don't inherently have this ERG S over there. And just come down here. And we just call this my static method, right? And essentially by doing this, what are we doing? We're calling the static method. That's what's actually happening here. So here it is with caudal are static method. Then if we, if we were to maybe call our public method, let's see what would happen. Public method. So there is a public method over there. There's a bit of an error over there. Why is that? There is an arrow over there? Because the way that we need to call a public method is we need to call. We need to create an object, first of all, in order for us to access that. You see that to access the public methods. So this is clearly an error here. Let's call it, let's just say, let's compile an arrow. Those compiles and error, meaning that with this, what we experience is an error. But then let's call him on main class, which is called HelloWorld. And just say my object. Then we just say new hello-world and we close that. And then we call it my object again. And then with this time we just said dot my public method. It's already being, you could say dumb, false, right? That. And as you can see, there's no error. And essentially what we're doing here is that we're creating an object of An object of Hello World, That's a main class, right? And then right here, essentially what we're doing is that we're calling the public method on the object we just created. So if we were to run this, let's just see what we essentially get. Normally, as you can see, there's no error at all. Then we should have the first one showing static methods can be called without creating objects. Voila. Then we also have public methods must be called by creating objects. As we can see, we had to create an object to ride day, right? So essentially that's the difference between the two, right? And just to further elaborate this more, we could even talk about how we access methods within an object, right? So let's say you are to create, let me just put the downforce access methods with an object. So let's use it to create a car. A car object named my car. You could just call on MF lot of throttle of a full throttle and over speed right on the my car. Object and then just simply run the program. And if that doesn't make sense, let's, let's pick an example of that. So let me just remove all of this. We don't we don't need any of this for now. Probably just this could say this has me always go back into my second keyboard. But then for now, let's just do this. Let's just create full throttle. Create a full throttle bit of a typo where there is food thrown with a big T over there. And we're creating a full throttle method over here, right? So essentially that's it. So we'll just say public, void, foo, throttle. And we have this, close it up like that. Then within this method, all this method does is that it prints out system dot out, dot print LN, it prints out the following statement. The car is going as fast as it can. Yeah, because going as fast as it can. Alright. Then what we wanna do next is we want to create a speed method as well. Alright? And add a parameter. So we'll just call it public void speed. The initial one most public void, full throttle. This one uses public void speed. And then right in this bit here, which is going to put our parameter and call it max speed. That's the name of our integer value that should be in there. It should represent the maximum speed. So we'll just say system out, print LN. And right in there we will call the max speed. And max speed is, and right outside there will call on max speed. This is the integer value that we want, right? Then next thing we wanna do is we want to just, um, that is inside, of course, lower caps. Inside Hello World. What we wanna do is call the methods on my car object, right? So there we have it will say public, static, void now. And then we have all string here with a RGS here and there we have it. And we'll just call Hello World. Hello World, and just say my car for example. And then we just say new and Hello world again. So essentially here as you know, we're just creating my car object. That's what's going on. So the object exists. Now, if we wanted to go public on this, we could definitely make use of the object. So we just link this to our method of throttle. So essentially therefore what we're doing is that we're calling the full throttle method. Then we just say again, my car, and then we allocate or speed at maybe 25. So by shadowing, we're calling the speed math PFAD. That's what's going on here. Right? Then. You just want to make sure there's no space over here. It should just be public static void. There should be a main here that I left out. Main. Yeah, good. And we run this and should tell us that the car is going as fast as it can firstly and then tell us the max speed as well. So there it is. The car is going as fast as it can that we have it. And the mx b is 25, right? So just to elaborate what's going on further here. Firstly, we created a custom hello world-class. That's what's going on with the class keyword. And then secondly, we created the full throttle method here. Not just this full throttle, but also the speed method. Except in the speed method, we had a parameter which is an integer, is an integer, whatever that is inside of this as a parameter. But our integer here or at our parameter is an integer and it's called a max speed parameter. Then we simply said in order for us to use our mean, our, our Hello class, HelloWorld class. And it's my fault. We need to create an object of the hello world class, which is exactly what we did. We created an object over here, right? Then the next thing that we did was we said we created an object obviously using the new keyword over there. And then we call on the full throttle and speed methods on the mica object and run the program. And name object followed by the dot, followed by the name of the method that we're interested in. And it's just worth noting that we can add an int parameter of even if 200 inside the speed method, right. 20. Constructors: So just remember, something worth noting is just that. Remember that the dot is used to access the objects, objects, attributes, and methods. So it's just worth noting that because that comes in very handy as you progress, especially feather in the whole aspect of what we're still doing at the moment, right? Awesome. So the next thing that I want us to look into is what is called constructors. Constructors. And this is something that will come in very handy in as you advance further and further. So, just bear in mind that a constructor itself. Constructor is a special method, a special method that is used to initialize objects as simple as that. Viola. So simply, we call the constructor when an object of a class is created and it can be used to set initial values for object attributes. Alright? So an example of this would probably be something like, let's come right up here and see if I can give you an example of this. So right now we're talking about a constructor. So let's say that we have something like int x being just like that. In essence, we are creating a class attribute. Just make sure this is a comment created the class tree Butte. We have created a class attribute over there. Then next thing we do is we create a class constructor. Now, main focus of what we're doing right now. For our class, which is the HelloWorld class. Awesome. So we just say public. And then we say hello world. And then we'll just do this and close that light that. And yeah, let's just make sure it's opened up like that rather. And here we just name our attribute and give it a seven, for example. Upon giving it a seven, what we next do is that we just have our common method, public void, main, string, or NGS. And we create an object essentially which is going to be hello world. And just send my OBJ. And then we say new hello world and we close that. That means what have we done? We have created an object of our class, which will be used to call a constructor, right? So we have created an object that will call the struct. Does the object of our cluster BU definitely call a constructor? So right in here, what I'm gonna do is I'm just going to set my, then we have x over the, essentially we are printing the value, value of x. So let's just see if we can get a seven over there. That is perfect. We have our seven. So it's just worth noting that the constructor name must match the class name and it cannot have a return type like int void for example. And also note that the constructor is called when the object is created and all classes have constructed by default. And if you do not create a class constructor yourself, Java creates one for you. However, then you're not able to set initial values for object attributes, right? So another thing that's worth us looking definitely into is what is called as constructor. Constructor param. So a constructor parameter. Constructor parameters, essentially they can, constructors themselves can take parameters which used to any lie attributes. Alright, so here's an example that we can definitely use as an application of what we are talking about here. Let's just console everything here that we have done so far. Rather up until at least some puzzle this, we say x is equals to y. And then we have not defined y yet. But rather what we're going to do is that we're going to define it right there and call it int y. And then right in here as well. What we're gonna do is we're just going to say object. And then right in here, we're going to put a number corresponding to the value of y, because that's how we mentioned that hello world has a parameter. It's an integer of y. And whenever I see Hello World, I need to make sure that I have it as an integer y whenever I see that as a class. So what I'm gonna do is I'm just going to say my end. And then x and I run it normally should be eight, because x is equals to y. So there it is, just eight, right? Just ate and you can have as many parameters as you want. So for example, here it could be an integer called year. For example, just an example really. And in which, for example would have to definitely modify this. Let's say this was like model, yeah, in terms of maybe we're talking about costs, maybe. So this would be like your model here. And then below it you probably want to look into the string. I don't need this comment for now. And then have a string that would tell us what the name of this car model name. And then because we have them like that will suggest an integer here would be the air stream just calling on the name. Yeah. Then essentially what we're gonna do is we're just going to give them model name would be would essentially just be equivalent to somebody asked him for the name. And then model would just be tantamount to me. Just say what is the yeah. Associated with the car we're talking about. And then I'll just say in here, main, here are the Hello World. Here. We'll just definitely give it the name First. Let's call it a Ford example. Then on this ford, rather, we're going to start with the year first. So it's gonna be 1967. And we put the name would be fought, for example, 1967 board. And it's just a matter of making sure that we printed well now. So how will we print this out? Well, it's no longer just an object, so I'll just call it my car here. I call this my car dot. Then it's just a matter of us choosing what exactly do we want. So we have it in the following manner. Then we call on the not just the year but the name as well modal name. So it should say 1967, Ford as well. So there it is. 1967. Ford does the output that we get, right? So essentially that's about it when it comes to construct this. That's the bothered when it comes to constructors in deed, right? 21. Modifiers: Alright guys, so the next thing that I definitely want us to look into is what is called modifiers, right? So let me just put that here because there's a bit of some commentary that's going to be taking place where here. So we call them Phi is, right. And they minded modifiers, something that we've been using already. Bear in mind that for example, whenever we say public class HelloWorld, public is a modifier, right? So we types or other groups of modifiers. Modifiers can be named in terms of or rather grouped in terms of the access modifiers, which is an example of our public. We can have access modifiers or we can have none access modifiers. Alright? So what are access modifiers? Access modifiers themselves are inherently those that control access just like the name says, Really access to whatever coding that you have, right? And then this one is do not. They do not control access. But they provide pro vide. Other functionality. Yeah, awesome. So those are the non access modifiers. Public, for example, public, as we've been talking about, public is an example of an access modifier. It. And just with this that I'm about to show you because it's a bit of some commentary that would definitely going to do over here, just so that you can thoroughly understand exactly what we're doing here. And I'll give an example starting off with the public. So essentially what public is, is that public is allowed those or rather what it means is that we're talking about a class that is accessible by other classes. It's a class that are accessible by another glass if you want. Then we could also talk about a modifier called default modifier. All this are access modifiers, by the way, should probably just make them clear that these are access modifiers. We also have default and default. What it means is that the class is only accessible by classes in the same package. Class. Simple Bye classes in the same package. Now, if you're wondering what are same package as we could be talking about this for example, this is a package that we're talking about. So we could have multiple packages and but it's a container containing classes really. You can think of it more like that. And we use this when we don't specify a modifier. So it means this is used. Java automatically uses this. This is used when you don't specify by modifier, it's the default one. If you wanted to, could definitely say that. Yeah. Alright, and then four attributes, methods and constructors you can use. Any of this really could use, not just public. And as we know that P has got to be small t. And then four attributes, attributes, methods, and constructors. We could have the following. We could still use public. Here. This would mean that our code is accessible for all clusters. Then if it's private. If it's private, it's a different thing. It's only code is only accessible. We then declared class, so it's private. And then if it's default, it means that we're talking about. Same package. Soybeans is still the same thing as we already mentioned over here. So I'll just do this to refer or autotrophs show that it's same thing, but rather here just for same package code as accessible on the same package basis. Then we could also have protected. And when a code or whatever you want to modify is protected, it means that code is accessible in the same package as well. And sub classes. This will see much further and helps very much, especially when we start talking about inheritance, superclasses and subclasses, it's quite valuable that you know that. Yeah. Right. So the next thing that I want us to look into is what we call the non access modifiers. Yeah. With a non-access modifier is let me just put them down for us. We are talking about Nan access modifiers. And with the non access modifiers, right? Really, you can either use final or abstract. That's the, that's the k is at least four classes. Classes. You can only use Final it all up struct. And if we're talking about something being final, what we're saying is that the class can not, the class cannot be inherited, Can not be inherited by the process. So again, this comes in very handy, or rather you understand it further as we do inheritance, which we're yet to do. This is just me. Building up to that. I'm here with abstracting means that the class can not be used to create objects. So in order for you to access an abstract class, it must be inherited from another class. Alright? So for, this was the case for classes. But then if we're talking about attributes and methods, then when we're referring to something being final, it means what? It means that that thing or that attribute or that method cannot be overridden. Overwritten. Show you still remember the example that we did above. This cannot be over written one more hour or are there some people would even some modified. Then if it's static, we also have static. If something is static of attributes and methods are static, it means that our attributes and methods belong to the class. Dan, Rather than an object. Belong to. They belong to the class. Rather than object. Yeah. And if it is abstract, it means what it means that it can only be used, can only be used in an abstract class. And can only N can only be used on methods, not on anything else. So just bear in mind that the method does not have embody. For example, something like abstract void run so that the body itself is provided by the subclass inherited from, right. So it's just some extra information that you need to bear in mind is suppose. We could also talk about how there is also transient, which isn't very common to use, but it still exists. So it means what attributes and methods are skipped when serializing the object containing them? Send it skipped. Using the object contained in them. Then we also have synchronized. So what does synchronized essentially mean? When something is synchronized, essentially what we're saying is that I think I left something over here. Sin colonized. Yeah. That's the right spelling. Synchronized. It means that our methods can only be accessed by one thread at a time, right? So it's important that I do state that here, this is a method I'm only referring to. Methods can only be accessed by one thread at a time. Then if it's volatility or rather volatile, if you want. If I use volatility means that the value of an attribute is not couched thread locally and this is always read from the main memory, right? So again, definitely not something that you'd be seeing a lot of times. But if costs, programming is so big with Java, sorry, it will ultimately depend on what it is that you are quoting. This awesome concepts that will progressively find ourselves doing locally and is always read from main memory. This itself was no t here on Monday. Yeah, So this are the axis n none access modifiers that you definitely do want to keep in mind. And just now we'll just do some examples, just exploring this much further. So an example of this would be something like this. Let me just delete all of this. We don't need this anymore. So it say final. There's a modifier in x on an attribute here and give it maybe 19. And then we say final double Pi and Pi itself as we know, it's given by 3.14. Yeah, 3.14 is actually 3.1428. So let me just to aid and progressively, and so on it goes. So we're stating our modifiers is being finite. That means that they cannot be overridden or modified. We cannot lead on defining new value of X or the new value of pi, right? And then here comes on method. We say public, static, void, main, and then this string. And we just make sure that we have alright, keyboard over their RGS and we ingest open that up. And right in there we create an object. So we say hello world. And then my J is equals to new hello-world name of my class. I just come down and then as that and start exploring something else. So let's start like this. Let's just say my OBJ and then I say x. And then let's see what we get from this is gonna be interesting. Things in error. They, why is then error? Well, as we can see, error. Alright, why? Because it can not assign value of x, y because we declared it as final. It meant that it cannot be modified or changed in any manner. Even if we were to try the pie and just try to modify our Pi as well. A similar thing would definitely happened with five were to say, Oh, new value of pi is just 3.14, for example. Nothing wrong with that, but they still an error. Why is then error is an error because we're modifying the value that was declared as being final. That should not be changing. Cannot assign a value of Pi sine, alright, Yeah, Yeah, Yeah, right. So let me just try and print out and just say, Hey, system, dot out, dot print. And then we print out x for example. And we see what will happen. So if we print out x, just one here, remember we printed out with object. So there is my object. Let's see what, what we get. Now. Obviously this one, we're going to put it in a comment because we know that there's an error there. We don't need that. And we run it. And let's just see. Taking a bit off some time here to load. Still loading. That is maintain does because we define x as 19, object is x. And if I were to change this for example, and just make this all pi, then let's see what comes of this. Now. Let's see if it gives us 3.148. That is 3.1428, right? So that's an example of us using the final modifier. Final modifier, which we know to be in non-access modifier. Now let's use another non-access modifier, which is a static modifier. So or are they understand it much further, right? So with that one, It's a metal of us just understanding even every time when we have something called static. Static method means that it can be accessed without creating an object of a class. Unlike public where we already spoke about this one, we're talking about static versus non-static. Wait. Just to put this in perspective, let me just remove everything here. I'll probably just give this guy here because I know that I don't have one keyboard. And just create a static method. I say just static, void, my static method. And it's definitely open. And just call it a system out, dot, print and write in there. Probably write something like static. Methods can be called without creating objects. Yeah. 22. Access & Non-Access Modifiers : Then just look at public method and look into a public void. Just create something like public void and then just call it my public void. Now, public method, that is rather here, let's print out something like system that are pruned. So say public methods must be cold. By creating objects. Then we have a lot. Some people would say main method, but we'll just call it our HelloWorld method. And this one will just be something like this public, static, void main. And we'll talk about this train G S over and just go down and just call on our static method. Just make sure I have those curly braces in there. Yeah, my static method, essentially I'm calling this static method colin, the static method. By so doing. Then, if I look at my public method, if I were to try and call this, let's just see. This already is an indication that something was wrong as it's not been suggested to me, that there's an error. Why? Because I need to create an object in order for me to start using this right. Here is an error here. So I need to put this as a comment and just create my Hello World object. Hello. Alright, I think it's time for a change. Now. My o, for now. I've been calling my OBJ for too much, for too long or other. And hello world and my OH, and this colored man public method that has been suggested for me. And essentially I'm calling the method now. If I run this, normally it should work. Now I should be able to print out the public method as well, as well as the static one. So I should see both statements smoke just one of them should see static methods can be called without creating objects. And I should be able to see public methods must be called by creating objects as well. Let's see. It's loading as well. There it is. We have both of them. Static methods can be called without creating objects. And we have public methods can be called a must be called by creating objects. Yeah, beautiful. So there we have it. There we have it. Then the last modified that we'll look into it is what we call the abstract modifier. As we know, the abstract modifier belongs as well to the non-access modifier as well. Yeah. And it can work for classes and four attributes, right? So abstract. I'm just going to just remove all of this again. And we just make sure that we have everything in place. Okay, beautiful. Alright. So instead of calling this public, we'll just call it abstract obstruct. There's abstract class. And with Officer plus we will just call on, I don't need this static method anymore. And then I'll just say something like maybe public String fname, which is for my firstName, and call it Will. And public end. Age as well, which is 24 years old. And then there is public abstract void as well. Study. It means that this is an abstract method. Yeah. This is an abstract method. Yeah, definitely. And we just make sure that this is closed out like this. Definitely like that. Good. Then just below it, what we'll do is we'll have something like a subclass, which really we inherit from Hello World. And with all subclass will just say clusters, meaning that its default if you want, if we were to leave it as just the cost. So if they assaults student big S and we say extends inheriting now, hello world. And we open that up. Possibilities are endless. Now this so we have public and Close click Command. Alright, so the next thing that I want us to look into is what is called as Java encapsulation. So let's just have that over here. This is Java encapsulation. So what Java encapsulation means is for us to really understand what it means really is that we need to understand what encapsulation encapsulation is. It means to to make sure that sensitive data is hidden from users. And in order for us to achieve this, we must one, declare class variables. Slash attributes, of course, actually beats as private. Secondly, provide, we want to make sure that we provide Public get and set methods axis and the value of private variable. Yeah, so this is something very important as well. So you, we already did it that private variables can only be accessed within the same class and outside class has no access to it. However, we know that it is possible to access them if we provide public get and set methods, right? So they GET method returns the variable value and the set method sets the variable. So the syntax for both is that they start with either get all set followed by the name of the variable with the first letter in upper case. An example of this would be, let's say public class. As they were suggesting already here. Hello world. Awesome. And then write in there, what we wanna do is we want to put something like a private string and then call it a name. And just make sure we have that closed. So Ben, mind that when it's private, private means restricted access. So for security reasons, we definitely do want to have such things in place. We don't want everybody having access to everything in your Code as they can definitely hack your files and just get a lot of information out of you. Then we have getName. And we open that. And we say return name. Return name. Then that's a getter. Now we have our setae as well. And with all setup, we'll just say public void setName. And just call on this training for new name. And have this open and just say this name as equivalent. New name. Excellent. Excellent. So if we run this, let's just see what we get. 23. Class Project: Alright, so thank you guys for joining me for this course and for your class project. What I want you to do is I want you to, with all the trivalent right now, I will attach a file here. I want you to go right into that file. I want to read through that. And there are some exercises that I've attached as well that I would like you to go through and just submit for me. Alright, cheers, and I look forward to seeing you in the cost dashpot.