If subclass (child class) has the same method as declared in the parent class, it is known as method overriding in Java.

In other words, If a subclass provides the specific implementation of the method that has been declared by one of its parent class, it is known as method overriding.

Usage of Java Method Overriding

  • Method overriding is used to provide the specific implementation of a method that is already provided by its superclass.
  • Method overriding is used for runtime polymorphism

Rules for Java Method Overriding

  1. The method must have the same name as in the parent class
  2. The method must have the same parameter as in the parent class.
  3. There must be an IS-A relationship (inheritance).

Example of method overriding

In this example, we have defined the run method in the subclass as defined in the parent class but it has some specific implementation. The name and parameter of the method are the same, and there is IS-A relationship between the classes, so there is method overriding.

//Java Program to illustrate the use of Java Method Overriding  
//Creating a parent class.  
class Vehicle{  
  //defining a method  
  void run(){System.out.println("Vehicle is running");}  
//Creating a child class  
class Bike2 extends Vehicle{  
  //defining the same method as in the parent class  
  void run(){System.out.println("Bike is running safely");}  
  public static void main(String args[]){  
  Bike2 obj = new Bike2();//creating object  
  obj.run();//calling method  

Can we override the static method?
No, a static method cannot be overridden. It can be proved by runtime polymorphism, so we will learn it later.

Why can we not override the static method?
It is because the static method is bound with class whereas the instance method is bound with an object. Static belongs to the class area, and an instance belongs to the heap area.

Can we override the java main method?
No, because the main is a static method.