polymorphism example in java | polymorphism in java

Polymorphism in Java

Polymorphism in Java is a concept by which we can perform a single action in different ways. Polymorphism is derived from 2 Greek words: poly and morphs. The word "poly" means many and "morphs" means forms. So polymorphism means many forms.

There are two types of polymorphism in Java: compile-time polymorphism and runtime polymorphism. We can perform polymorphism in java by method overloading and method overriding.

If you overload a static method in Java, it is the example of compile time polymorphism. Here, we will focus on runtime polymorphism in java.

Runtime Polymorphism in Java

Runtime polymorphism or Dynamic Method Dispatch is a process in which a call to an overridden method is resolved at runtime rather than compile-time.

In this process, an overridden method is called through the reference variable of a superclass. The determination of the method to be called is based on the object being referred to by the reference variable.

Let's first understand the upcasting before Runtime Polymorphism.

Upcasting

If the reference variable of Parent class refers to the object of Child class, it is known as upcasting. For example:

 

java polymorphisem

class A{}

class B extends A{}

A a=new B();//upcasting

For upcasting, we can use the reference variable of class type or an interface type.

For Example:

implement I{}

class A{}

class B extends Aimplementing{}

Output:

B IS-A A

B IS-A

B IS- A Object

Example:

    class Bike{  

    void run(){System.out.println("running");}  

}  

   class Splendor extends Bike{  

   void run(){System.out.println("running safely with 60km");}  

  

    public static void main(String args[]){  

    Bike b = new Splendor();//upcasting  

    b.run();  

   }  

}  

Output:

Running safely with 60km

Java Runtime Polymorphism Example: Bank

Consider a scenario where Bank is a class that provides a method to get the rate of interest. However, the rate of interest may differ according to banks. For example, SBI, ICICI, and AXIS banks are providing 8.4%, 7.3%, and 9.7% rate of interest

 

polymorphisem in java

    

   class Bank{  

    float getRateOfInterest(){return 0;}  

}  

   class SBI extends Bank{  

   float getRateOfInterest(){return 8.4f;}  

}  

    class ICICI extends Bank{  

    float getRateOfInterest(){return 7.3f;}  

}  

   class AXIS extends Bank{  

    float getRateOfInterest(){return 9.7f;}  

}  

    class TestPolymorphism{  

    public static void main(String args[]){  

    Bank b;  

    b=new SBI();  

   System.out.println("SBI Rate of Interest: "+b.getRateOfInterest());  

    b=new ICICI();  

    System.out.println("ICICI Rate of Interest: "+b.getRateOfInterest());  

   b=new AXIS();  

   System.out.println("AXIS Rate of Interest: "+b.getRateOfInterest());  

}  

}  

 

Output:

SBI Rate of Interest:8.4

ICICI Rate of Interest: 7.3

AXIS Rate of Interest:9.7