f 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 subclass provides the specific implementation of the method that has been provided by one of its parent class, it is known as method overriding.
Usage of Java Method Overriding
- Method overriding is used to provide specific implementation of a method that is already provided by its super class.
- Method overriding is used for runtime polymorphism
Rules for Java Method Overriding
- method must have same name as in the parent class
- method must have same parameter as in the parent class.
- must be IS-A relationship (inheritance).
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.
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 is same and there is IS-A relationship between the classes, so there is method overriding.
Real example of Java Method Overriding
Consider a scenario, Bank is a class that provides functionality to get rate of interest. But, rate of interest varies according to banks. For example, SBI, ICICI and AXIS banks could provide 8%, 7% and 9% rate of interest.
Can we override static method?
No, static method cannot be overridden. It can be proved by runtime polymorphism, so we will learn it later.
Why we cannot override static method?
because static method is bound with class whereas instance method is bound with object. Static belongs to class area and instance belongs to heap area.
Can we override java main method?
No, because main is a static method.