Inheritance:

Inheritance can be defined as the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.

When we talk about inheritance the most commonly used keyword would be extends and implements. These words would determine whether one object IS-A type of another. By using these keywords we can make one object acquire the properties of another object.

Example:

public class Animal{
}

public class Mammal extends Animal{
}

public class Reptile extends Animal{
}


public class Dog extends Mammal{
   public static void main(String args[]){

      Animal a = new Animal();
      Mammal m = new Mammal();
      Dog d = new Dog();

      System.out.println(m instanceof Animal);
      System.out.println(d instanceof Mammal);
      System.out.println(d instanceof Animal);
   }
}

In Object Oriented terms following are true:


Animal is the superclass of Mammal class.


Animal is the superclass of Reptile class.


Mammal and Reptile are sub classes of Animal class.


Dog is the subclass of both Mammal and Animal classes.