Objective:
In the previous article Set and File handling in Java, we have learned about the Set function and the ways of file handling in Java. In this article,, we are going to learn about the Overriding method in java.
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 subclass provides the specific implementation of the method that has been provided by one of its parent class, it is known as 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 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).
Example 1:
class Vehicle{
void run(){System.out.println("Vehicle is running");}
}
class Bike2 extends Vehicle{
void run(){System.out.println("Bike is running safely");}
public static void main(String args[]){
Bike2 obj = new Bike2();
obj.run();
}
}
//Output:
Bike is running safely
In thi above 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.
Example2:
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.
class Bank{
int getRateOfInterest(){return 0;}
}
class SBI extends Bank{
int getRateOfInterest(){return 8;}
}
class ICICI extends Bank{
int getRateOfInterest(){return 7;}
}
class AXIS extends Bank{
int getRateOfInterest(){return 9;}
}
class Test2{
public static void main(String args[]){
SBI s=new SBI();
ICICI i=new ICICI();
AXIS a=new AXIS();
System.out.println("SBI Rate of Interest: "+s.getRateOfInterest());
System.out.println("ICICI Rate of Interest: "+i.getRateOfInterest());
System.out.println("AXIS Rate of Interest: "+a.getRateOfInterest());
}
}
//Output:
SBI Rate of Interest: 8
ICICI Rate of Interest: 7
AXIS Rate of Interest: 9
Difference between Method overloading and Method Overriding:
|
No. |
Method Overloading |
Method Overriding |
|
1) |
Method overloading is used to increase the readability of the program. |
Method overriding is used to provide the specific implementation of the method that is already provided by its super class. |
|
2) |
Method overloading is performed within class. |
Method overriding occurs in two classes that have IS-A (inheritance) relationship. |
|
3) |
In case of method overloading, parameter must be different. |
In case of method overriding, parameter must be same. |
|
4) |
Method overloading is the example of compile time polymorphism. |
Method overriding is the example of run time polymorphism. |
|
5) |
In java, method overloading can't be performed by changing return type of the method only. Return type can be same or different in method overloading. But you must have to change the parameter. |
Return type must be same or covariant in method overriding. |
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