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Method Overriding in Java

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 which 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).
Java Rules for Method Overriding

Understanding the problem without method overriding

Let's understand the problem that we may face in the program if we don't use method overriding.

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Output:

Vehicle is running

Problem is that I have to provide a specific implementation of run() method in subclass that is why we use method overriding.


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.

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Output:

Bike is running safely

A real example of Java Method Overriding

Consider a scenario where Bank is a class that provides functionality to get the rate of interest. However, the rate of interest varies according to banks. For example, SBI, ICICI and AXIS banks could provide 8%, 7%, and 9% rate of interest.

Java method overriding example of bank

Java method overriding is mostly used in Runtime Polymorphism which we will learn in next pages.

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Output:
SBI Rate of Interest: 8
ICICI Rate of Interest: 7
AXIS Rate of Interest: 9

Can we override 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 static method?

It is because the static method is bound with class whereas instance method is bound with an object. Static belongs to the class area, and an instance belongs to the heap area.


Can we override java main method?

No, because the main is a static method.


Difference between method Overloading and Method Overriding in java

Click me for the difference between method overloading and overriding






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