The extends Keyword in Java

An object can acquire the properties and behaviour of another object using Inheritance. In Java, the extends keyword is used to indicate that a new class is derived from the base class using inheritance. So basically, extends keyword is used to extend the functionality of the class.

A program that demonstrates the extends keyword in Java is given as follows:

Example

 Live Demo

class A {
   int a = 9;
}
class B extends A {
   int b = 4;
}
public class Demo {
   public static void main(String args[]) {
      B obj = new B();
      System.out.println("Value of a is: " + obj.a);
      System.out.println("Value of b is: " + obj.b);
   }
}

Output

Value of a is: 9
Value of b is: 4

Now let us understand the above program.

The class A contains a data member a. The class B uses the extends keyword to derive from class A. It also contains a data member b. A code snippet which demonstrates this is as follows:

class A {
   int a = 9;
}
class B extends A {
   int b = 4;
}

In the main() method in class Demo, an object obj of class B is created. Then the values of a and b are printed. A code snippet which demonstrates this is as follows:

public class Demo {
   public static void main(String args[]) {
      B obj = new B();
      System.out.println("Value of a is: " + obj.a);
      System.out.println("Value of b is: " + obj.b);
   }
}

Vikyath Ram

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Updated on: 30-Jul-2019

4K+ Views

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