Inheritance

Inheritance enables you to extend the functionality of an existing class.

In inheritance, a superclass or a parent class is the one from which another class inherits attributes and behavior. A subclass or child class is a class that inherits attributes and behavior from a superclass.

Note

Th object class is called as a supermost class. Inheritance is applicable only for nonstatic classes.

A Java program with an inheritance example

The following is an example of inheritance in a Java program:

package MyFirstPackage;

class SampleClass1 {
  void sampleMethod(){
  System.out.println("executing sample method");
}
 }
 
class SampleClass2 extends SampleClass1 {
    void sampleMethod1(){
    System.out.println("executing sample method 2");
  }
  }

  
public  class Inhertance {
  public static void main(String[] args) {
    SampleClass2 methodcall = new SampleClass2();
    methodcall.sampleMethod1();
    methodcall.sampleMethod();
  }
}

The output of the preceding code will be as follows:

executing sample method 2
executing sample method

An abstract class

An abstract class is a class that has one or more methods with no definitions or body. This class must be inherited and must be a superclass and obviously a nonstatic class.

An example of a Java program with an abstract class

The following is an example of an abstract class in a Java program:

package MyFirstPackage;

abstract  class sample_abs {

  abstract void abstr_method ();
  abstract void abstr_method1 ();
  abstract void abstr_method2 ();
  abstract void abstr_method3 ();
  abstract void abstr_method4 ();
  
  void nonabstr (){
  }
}

abstract  class sample_abs1 extends sample_abs {
  
  void abstr_method () {
  }

  void abstr_method1 () {
  }

  void abstr_method2 () {
  }

  void abstr_method3 () {
  }

  public class AbstractClass extends sample_abs1 {
  
    void abstr_method1 () {
    }
  
  void abstr_method4 () {
  }
  
  public static void main(String[] args) {
    System.out.println("Abstract class demo");
  }
}

The output will be as follows:

Abstract class demo