Java Inheritance

• Inheritance is one of the main features of OOP that allows us to create a new class from an existing class.

• Due to inheritance, it is possible to inherit attributes and methods from one class to another.

• Inheritance can create two classes as follows:

  • Subclass - The new class that is created is known as a subclass or child or derived class.
  • Superclass - The existing class from which the child class is derived is known as the superclass parent or base class.

• The "extends" keyword is used to perform inheritance in Java.

• In the given program, Dog2, Cat2, Fish 2, and Bird2 are the subclasses or child classes that inherit the attributes name and age from the parent or superclass Animal.

Java Polymorphism

• Polymorphism is one of the main features of OOP which says more than one form.

• Polymorphism occurs when we have many classes that are related to each other by inheritance.

• That means the same method or operator or object can perform different operations in different scenarios.

• In the given program, a superclass called Animal has a method called show().

• Subclasses of Animals could be Dog2, Cat2, Fish 2, and Bird2 also have their implementation of method show().

• In short, Inheritance lets us inherit attributes and methods from another class.

• Polymorphism uses those methods to perform different tasks.

• This allows us to perform a single action in different ways.

Java Program

class Animal     // Parent or Superclass Animal
{  
String name;    // Animal attribute name
int age;        // Animal attribute age
public void show()       // Animal method show
{
System.out.println("\nThese all are the animals of PetOwner2");
}
}  
class Dog2 extends Animal     // Child or Subclass Dog2
{  
public void show()       // Child class Dog2 methos show   
{
System.out.println("\nThe Dog name is " + name + " and age of the Dog is " + age);
} 
}
class Cat2 extends Animal     // Child or Subclass Cat2
{ 
public void show()       // Child class Cat2 method show 
{
System.out.println("\nThe Cat name is " + name + " and age of the Cat is " + age);
} 
}  
class Fish2 extends Animal     // Child or Subclass Fish2
{ 
public void show()       // Child class Fish2 method show 
{
System.out.println("\nThe Fish name is " + name + " and age of the Fish is " + + age);
} 
} 
class Bird2 extends Animal     // Child or Subclass Bird2
{ 
public void show()       // Child class Bird2 method show 
{
System.out.println("\nThe Bird name is " + name + " and age of the Bird is " + age);
} 
}   
class PetOwner2        // The main class PetOwner2 for testing
{  
public static void main(String[] args)
{   
Animal a = new Animal ();   // Create a parent class Animal object
Animal d = new Dog2();   // Create a child class Dog2 object
Animal c = new Cat2();   // Create a child class Cat2 object
Animal f = new Fish2();   // Create a child class Fish2 object
Animal b = new Bird2();   // Create a child class Bird2 object

// Access attributes of parent class Animal
d.name = "Dog2";
d.age = 10;

c.name = "Cat2";
c.age = 8;

f.name = "Fish2";
f.age = 2;

b.name = "Bird2";
b.age = 14;

d.show();  // Call the show method form Dog2 subclass using Dog2 object
c.show();  // Call the show method form Cat2 subclass using Cat2 object
f.show();  // Call the show method form Fish2 subclass using Fish2 object
b.show();  // Call the show method form Bird2 subclass using Bird2 object
a.show();  // Call the show method form Animal superclass using Animal object
}
}

The output of the Java Program -