Core Java Development Course for Beginners - Part 8 - String, StringBuilder & Wrapper classes

This course is for anyone who wants to learn Java from scratch, polish java skills, face java interviews and prepare for java certifications.

Anyone can take this course and go from 0 developments skills to being expert in OOPs and core Java.
Java is the most popular language world wide and technologies like Servlets & JSP, J2EE, Struts, Spring, Hibernate, JMS or android for mobile applications are all based on core Java. 
Even Kotlin (android's new programming language) becomes easier if you know Java.

Having a sound understanding of core java concepts is necessary, if you want to learn advance concepts, frameworks and android programming.

Following Lectures are covered in Part-8

1.            String

In this lecture you will learn:

• How String instances are different from other instances?
• Different ways to create String instances.
• What is String literal?
• What is String immutability?
• What is String Pool table?
• The working of intern() method of String class.
• Correct way to compare two String instances for equality?

2.            Magic of String

In this lecture you will learn:

• An interesting scenario of intern() method, in which changing the position of System.out.println() statement changes the output.
• How garbage collection of String instances is different from other instances?

3.            Methods of String class

In this lecture you will learn:

• concat, compareTo, compareToIgnoreCase, replace, substring, startsWith and endsWith methods.
• Why java.lang.String class cannot be extended?

4.            StringBuffer and StringBuilder

In this lecture you will learn:

• The purpose of StringBuffer and StringBuilder classes.
• Difference between StringBuffer and StringBuilder classes.
• When to prefer StringBuilder class over String class?
• append, delete, insert, reverse and toString methods of StringBuilder/StringBuffer class.
• Method chaining of StringBuilder and String methods.

5.            Wrapper Classes

In this lecture you will learn:

• What are wrapper classes and how to create instances of wrapper classes?
• Important constructors of wrapper classes.
• static valueOf methods of all the wrapper classes.
• byteValue(), shortValue(), intValue(), longValue(), floatValue() and doubleValue() methods of numeric wrapper classes.
• static parse methods of wrapper classes.
• Cases for which NumberFormatException is thrown by constructors and methods of Wrapper classes.
• How to create a wrapper object without constructor or valueOf method?
• What is Auto-boxing and Auto-unboxing?
• What are the scenarios in which two instances of wrapper classes created through boxing are same?
• Cases for which java runtime will not auto-unbox the wrapper objects.
• Why is it a good programming practice to initialize all the variables?
• Why numeric wrapper types cannot be assigned to each other?
• Why you cannot extend from wrapper classes?