The extends keyword in Java programming language

We will learn in this tutorial about The extends keyword in Java programming language

extends is a keyword in Java language, which is used to inheritance process to inherit the property of the class (from the parent class to child class),like this

class A extends B{..........}

newly creating class or derived class use extends keyword to extend data members or methods of already exiting class or base class(inherit extra attributes).

Private variable and methods can not be inherit extends keyword

How to works extends keyword

public class Base_class{ 
//Data members(variable and methods)
}

This is a base class or parent class

public class Derived_class extends Base_class{
//child class inherits properties of base class
}

This is derived class inherit properties of Base class using extends keyword

Example

Program

public class A{
public int number1;
public int number2;
}

class B extends A{
public static add(){
add1=number1+number2
}
}

In this example, we inherit properties from class A, which means that class B will also contain a method add 1. Class B inherits properties from class A as number 1 and number 2 for calculation.

Example

class A{
public static int num1=45;
public static int num2=56;

}
class B extends A{
    void add(){
    System.out.println("Total of num1,num2 :"+(num1+num2));	
    }
    public static void main(String args[]){
        B obj=new B();
        obj.add();
    }
    
}

When the above code is compiled and executed, it will produce the following result

Addition of num1,num2 :101

There are other Java language keywords that are similar to the this keyword

implements keyword in java

interface keyword in java

Inheritance in Java

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