Method Overloading
If a class have multiple methods by same name but different parameters, it is known as Method Overloading.
If we have to perform only one operation, having same name of the methods increases the readability of the program.
Suppose you have to perform addition of the given numbers but there can be any number of arguments, if you write the method such as a(int,int) for two parameters, and b(int,int,int) for three parameters then it may be difficult for you as well as other programmers to understand the behaviour of the method because its name differs. So, we perform method overloading to figure out the program quickly.
Advantage of method overloading?
Method overloading increases the readability of the program.
Different ways to overload the method
There are two ways to overload the method in java
- By changing number of arguments
- By changing the data type
Example of Method Overloading by changing the no. of arguments
In this example, we have created two overloaded methods, first sum method performs addition of two numbers and second sum method performs addition of three numbers.
class Calculation{
void sum(int a,int b){System.out.println(a+b);}
void sum(int a,int b,int c){System.out.println(a+b+c);}
public static void main(String args[]){
Calculation obj=new Calculation();
obj.sum(10,10,10);
obj.sum(20,20);
}
}
Output:30
40
Example of Method Overloading by changing data type of argument
In this example, we have created two overloaded methods that differs in data type. The first sum method receives two integer arguments and second sum method receives two double arguments.
class Calculation2{
void sum(int a,int b){System.out.println(a+b);}
void sum(double a,double b){System.out.println(a+b);}
public static void main(String args[]){
Calculation2 obj=new Calculation2();
obj.sum(10.5,10.5);
obj.sum(20,20);
}
}
Output: 21.0
40
Why Method Overloading is not possible by changing the return type of method?
In java, method overloading is not possible by changing the return type of the method because there may occur ambiguity. Let's see how ambiguity may occur:
because there was problem:
class Calculation3{
int sum(int a,int b){System.out.println(a+b);}
double sum(int a,int b){System.out.println(a+b);}
public static void main(String args[]){
Calculation3 obj=new Calculation3();
int result=obj.sum(20,20); //Compile Time Error
}
}
int result=obj.sum(20,20); //Here how can java determine which sum() method should be called
Can we overload main() method?
Yes, by method overloading. You can have any number of main methods in a class by method overloading.
Let's see the simple example:
class Overloading1{
public static void main(int a){
System.out.println(a);
}
public static void main(String args[]){
System.out.println("main() method invoked");
main(10);
}
}
Output:main() method invoked
10