Different ways of Method Overloading in Java

Method overloading in java is based on the number and type of the parameters passed as an argument to the methods. We can not define more than one method with the same name, Order, and type of the arguments. It would be a compiler error. The compiler does not consider the return type while differentiating the overloaded method. But you cannot declare two methods with the same signature and different return types. It will throw a compile-time error. If both methods have the same parameter types, but different return types, then it is not possible.

Java can distinguish the methods with different method signatures. i.e. the methods can have the same name but with different parameters list (i.e. the number of the parameters, the order of the parameters, and data types of the parameters) within the same class. 

Geeks, now you would be up to why do we need method overloading?

If we need to do some kind of operation in different ways i.e. for different inputs. In the example described below, we are doing the addition operation for different inputs. It is hard to find many meaningful names for a single action. 

Ways of Overloading Methods

Method overloading can be done by changing: 

1. The number of parameters in two methods.
2. The data types of the parameters of methods.
3. The Order of the parameters of methods.

Let us propose examples in order to illustrate each way while overloading methods. They are as follows:   

Method 1: By changing the number of parameters.

Java

// Java Program to Illustrate Method Overloading
// By Changing the Number of Parameters

// Importing required classes
import java.io.*;

// Class 1
// Helper class
class Addition {

    // Method 1
    // Adding two integer values
    public int add(int a, int b)
    {

        int sum = a + b;
        return sum;
    }

    // Method 2
    // Adding three integer values
    public int add(int a, int b, int c)
    {

        int sum = a + b + c;
        return sum;
    }
}

// Class 2
// Main class
class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Creating object of above class inside main()
        // method
        Addition ob = new Addition();

        // Calling method to add 3 numbers
        int sum1 = ob.add(1, 2);

        // Printing sum of 2 numbers
        System.out.println("sum of the two integer value :"
                           + sum1);

        // Calling method to add 3 numbers
        int sum2 = ob.add(1, 2, 3);

        // Printing sum of 3 numbers
        System.out.println(
            "sum of the three integer value :" + sum2);
    }
}

Output

sum of the two integer value :3
sum of the three integer value :6

Method 2: By changing the Data types of the parameters 

Java

// Java Program to Illustrate Method Overloading
// By Changing Data Types of the Parameters

// Importing required classes
import java.io.*;

// Class 1
// Helper class
class Addition {

    // Adding three integer values
    public int add(int a, int b, int c)
    {

        int sum = a + b + c;
        return sum;
    }

    // adding three double values.
    public double add(double a, double b, double c)
    {

        double sum = a + b + c;
        return sum;
    }
}

class GFG {
    public static void main(String[] args)
    {

        Addition ob = new Addition();

        int sum2 = ob.add(1, 2, 3);
        System.out.println(
            "sum of the three integer value :" + sum2);
        double sum3 = ob.add(1.0, 2.0, 3.0);
        System.out.println("sum of the three double value :"
                           + sum3);
    }
}

Output

sum of the three integer value :6
sum of the three double value :6.0

Method 3: By changing the Order of the parameters 

Java

// Java Program to Illustrate Method Overloading
// By changing the Order of the Parameters

// Importing required classes
import java.io.*;

// Class 1
// Helper class
class Geek {

    // Method 1
    public void geekIdentity(String name, int id)
    {

        // Printing name and id of person
        System.out.println("geekName :" + name + " "
                           + "Id :" + id);
    }

    // Method 2
    public void geekIdentity(int id, String name)
    {

        // Again printing name and id of person
        System.out.println("Id :" + id + " "
                           + "geekName :" + name);
    }
}

// Class 2
// Main class
class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Creating object of above class
        Geek geek = new Geek();

        // Passing name and id
        // Note: Reversing order
        geek.geekIdentity("Mohit", 1);
        geek.geekIdentity(2, "shubham");
    }
}

Output

geekName :Mohit Id :1
geekName :shubham Id :2

Note: Now geeks you must be wondering what will happen when the method signature is the same and the return type is different?

Here the compiler will give an error as the return value alone is not sufficient for the compiler to figure out which function it has to call. Only if both methods have different parameter types (so, they have a different signature), then Method overloading is possible.  

Example 4 

Java

// Java Program to Illustrate Error Thrown in
// Method Overloading When Method Signature is Same and
// ReturnType is Different

// Importing required classes
import java.io.*;

// Class 1
// Helper class
class Addition {

    // Method 1
    // Adding two integer value
    public int add(int a, int b)
    {
        // Summing up
        int sum = a + b;

        // Returning the sum
        return sum;
    }

    // Method 2
    // Adding three integer value
    public double add(int a, int b)
    {
        double sum = a + b + 0.0;
        return sum;
    }
}

// Class 2
// Main class
class GFG {

    // Main driver method
    public static void main(String[] args)
    {
        // Try block to check for exceptions
        try {

            // Creating an object of above class
            Addition ob = new Addition();

            // Calling method 1 to sum 2 numbers
            int sum1 = ob.add(1, 2);

            // Printing sum of two numbers
            System.out.println(
                "sum of the two integer value :" + sum1);

            // Calling method 2 to sum 3 numbers
            int sum2 = ob.add(1, 2);

            // Printing sum of three numbers
            System.out.println(
                "sum of the three integer value :" + sum2);
        }

        // Catch block to handle exceptions
        catch (Exception e) {

            // Display the exceptions on console
            System.out.println(e);
        }
    }
}

Output:

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