Java Day 6: Return Data Types, Methods, and this Keyword

Return Data Types in Java

• Definition: The return data type specifies the type of value a method will return.
• Types of Return Data Types:
  • void → No return value
  • Primitive types → int, float, char, etc.
  • Non-primitive types → String, Array, Class Object, etc.
• Example:

 class Example { int add(int a, int b) { // Method returning an int return a + b; } } 

How to Create Methods

Method Definition

• A method is a block of code designed to perform a task.
• Syntax:

 returnType methodName(parameters) { // Method body return value; // (if returnType is not void) } 

• Example:

 class Example { void display() { // Method with no return value System.out.println("Hello World"); } } 

this Keyword in Java

• Definition: this refers to the current instance of a class.
• When to Use this?
  • To differentiate between instance variables and parameters with the same name.
  • To call another constructor in the same class.
  • To return the current class instance.
• Example:

 class Example { int num; Example(int num) { this.num = num; // Using `this` to refer to instance variable } } 

• When NOT to Use this?
  • In static methods (since static methods belong to the class, not an instance).
  • Outside non-static methods.

Global Elements in Java

Variables

• Static Variables (shared across all objects, belongs to the class)

 class Example { static int count = 0; } 

• Non-Static Variables (unique to each object)

 class Example { int id; } 

Methods

• Static Methods (can be called without an object)

 class Example { static void show() { System.out.println("Static method"); } } 

• Non-Static Methods (requires an object to be called)

 class Example { void show() { System.out.println("Non-static method"); } } 

Why Do We Need Methods?

• Code Reusability: Avoid repeating code.
• Modular Structure: Divides the program into smaller, manageable parts.
• Readability & Maintainability: Improves program clarity and debugging efficiency.

This covers return data types, method creation, this keyword, global variables/methods, and why methods are essential🚀