Method Overloading in java

Every class has one or more methods which are used to perform different functionalities in the application.

Can we have two methods having the same name in one class?

Yes, we can have two or more methods having the same name in one class, but the condition is their arguments list should be different.

What does it mean by different argument lists?

Argument lists can be different in the following ways.

1. No. of parameters passed in the method
2. Data type of parameters
3. Sequence of data type of parameters

Let’s understand method overloading with examples.

1. Method overloading by changing the no. of arguments:

We have a class companyDetails which is having 2 methods with the same name company, but no. of arguments passed are different.

package com.testingpool;

public class CompanyDetails {

	public static void main(String[] args) {
		CompanyDetails comp = new CompanyDetails();
		comp.company(1234);  // calling first method 
		comp.company(1234,"Shekhar"); 	 // calling second method with same name but different arguments
	}
	
	//first method 
	void company(int empid){
		System.out.println("Emp id is "+empid);
	}
	
	//second methos with the same name
	void company(int empid,String empname){
		System.out.println("Emp id is "+empid+" and emp name is "+empname);
	}

}

2. No. of arguments are same but datatypes of arguments are different:

We have one Addition class which is having 2 methods with the same name getSum. Both the methods have same no. of arguments (i.e. 2) , but their data types of arguments are different.

package com.testingpool;

public class Addition {

	public static void main(String[] args) {
		Addition sum = new Addition();
		sum.getSum(4,5);  // calling first method 
		sum.getSum(4.50,4.50); 	 // calling second method with same no. of arguments but different data type
		
	}
	
	//first method 
	void getSum(int a,int b){
		System.out.println(a+b);
	}
	
	//second method with different data type but same no. of arguments
	void getSum(double  a ,double b){
		System.out.println(a+b);
	}

}

3. Sequence of data type of arguments is different:

We have a class StudentDetails which is having same name method called Student. Method Student have the same no. of arguments and dats types, but sequence of data type is different.

package com.testingpool;

public class StudentDetails {

	public static void main(String[] args) {
		StudentDetails stud = new StudentDetails();
		stud.Student(1234,"Madhur");  // calling first method 
		stud.Student("Manan",6789); 	 // calling second method with same no. of arguments but their sequence of datatype is different
	}
	
	//first method 
	void Student(int rollno,String name){
		System.out.println("Student's roll no and name :- "+rollno +"--"+name);
	}
	
	//second method with different data type but same no. of arguments
	void Student(String  name ,int rollno){
		System.out.println("Student's name and roll no :- "+name +"--"+rollno);
	}

}

The reason why Method Overloading is not possible by changing the return type of method?

If there will same methods with changed return data type, then there will be confusion which method to call. There you will get compile time error.

public class Addition {

	  int getsum(int a,int b){     //Compile Time Error 
		  System.out.println(a+b);
	  }  
	  double getsum(double a,double b){    //Compile Time Error 
		  System.out.println(a+b);
	  }  
	  
	  public static void main(String args[]){  
		  Addition obj=new Addition();  
	  int result=obj.getsum(20,20); //Compile Time Error  
	  
	  } 
}

Is it possible to overload the main method?

Yes, it is possible to overload the main method. For more detail on main method Click here.