Polymorphism means having many forms. The word “poly” means many and “morphs” means forms. In java, it is a concept that allows the user to perform a single action in different ways.
Take a real-life example: Consider a man and at the same time he can be a father, a husband, an employee that is he is having a different character and posses different behavior in different situations.
Similarly, a class in a program has a method and the subclass have the same method but with a different task to perform related to the first method. This is called polymorphism.
In Java polymorphism is mainly divided into two types:
- Compile-time Polymorphism or Static Polymorphism.
- Runtime Polymorphism or Dynamic Polymorphism.
1. Compile-time Polymorphism:
It is also known as static polymorphism. In this type of program, the flow of control is decided at compile time itself and if any error is found, they are resolved at compile time. This can be achieved by method overloading.
Method Overloading:
Method Overloading allows the user to have more than one method that has the same name, they are differed by the number of the parameter lists, sequence, and data types of parameters.
Example: With a number of arguments
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | class ExampleTest { int add(int x, int y) { return x + y; } int add(int x, int y, int z) { return x + y + z; } } public class Main { public static void main(String args[]) { ExampleTest obj = new ExampleTest(); System.out.println(obj.add(50, 30)); System.out.println(obj.add(20, 10, 20)); } } |
Output:
80
50
2. Runtime Polymorphism:
It is also known as Dynamic Method Dispatch. It is a process in which a call to an overridden method is resolved at runtime. This type of polymorphism is achieved by Method Overriding.
Method Overriding:
Method Overriding is a feature that allows the user to declare a method with the same name in a sub-class that is already present in a parent class. And that base is said to be overridden.
Example for Method Overriding:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | class Dog { public void display() { System.out.println("I am A Dog"); } } class breed extends Dog { public void display() { System.out.println("Breed: German Shepard"); } } public class BreedTest { public static void main(String args[]) { Dog d = new Dog(); // Animal reference and object Dog b = new breed(); // Animal reference but Dog object d.display(); // runs the method in Animal class b.display(); // runs the method in Dog class } } |
Output:
I am A Dog
Breed: German Shepard