How to implement fundamental OOPs concept (Polymorphism) in java??

     Poly means many. Polymorphism in java defines a single super class and that can be used for any sub classes. Even the class definition can be overridden and the methods can be overloaded with another definition.

The method overriding and method overloading java implementations are given below….

Java Program to implement Method overriding:

              Overriding is the process of redefining a function. This program overrides a function definition.

Steps:

• ·       Create a super class “Fruit” with a member function “color()” with a output statement.
• ·       Next, create a sub class “Apple” extends from super class “Fruit” with the function “color()”. Override the function with another definition.
• ·       Write a class “samplePoly” with main function.
• ·       Fruit myFruit = new Apple(); Using the base class, declare an object for sub class.
• ·       Call the sub class’s overridden function using the object.

class Fruit {

    void color() {

        System.out.println("Each Fruit has a color");

    }

}

class Apple extends Fruit {

    @Override

    void color() {

        System.out.println("Color of Apple is Red");

    }

}

public class samplePoly {

    public static void main(String[] args) {

        Fruit myFruit = new Apple();  // Creating an object for Apple - Overriden

        myFruit.color();  // Calling the overridden function

    }

}

Here is the output.

C:\raji\blog>javac samplePoly.java

C:\raji\blog>java samplePoly

Color of Apple is Red

Method overloading is given below.

Java Program to implement Method overloading:

“Same function name with different arguments” – A class can have many functions with same name with different arguments.

• Class “MathExpression”.
• mul() is a function which is having two different arguments.
• First mul() function gets two arguments,multiply it and return the output.
• Second mul() function gets three arguments, multiply it and return the result.

“sampleOverload.java”

class MathExpression {

    int mul(int x, int y) {

        return x * y;

    }

    int mul(int x, int y, int z) {

        return x * y * z;

    }

}

public class sampleOverload {

    public static void main(String[] args) {

        MathExpression oper = new MathExpression();

        System.out.println("The multiplication of two numbers are : "+oper.mul(5, 7)); 

        System.out.println("The Overloaded multiplication of three numbers are : "+oper.mul(4, 6, 8)); 

    }

}

Output:

C:\raji\blog>javac sampleOverload.java

C:\raji\blog>java sampleOverload

The multiplication of two numbers are : 35

The Overloaded multiplication of three numbers are : 192

This is the implementation of Polymorphism in java. This fundamental concept is useful for its flexibility and reusability.