Different ways of Method Overloading in Java - GeeksforGeeks

08 Mar, 2022
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. 
Method overloading can be done by changing: 
The number of parameters in two methods.The data types of the parameters of methods.The Order of the parameters of methods.
The number of parameters in two methods.
The data types of the parameters of methods.
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 classesimport java.io.*; // Class 1// Helper classclass 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 classclass 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);    }}
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 classesimport java.io.*; // Class 1// Helper classclass 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);    }}
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 classesimport java.io.*; // Class 1// Helper classclass 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 classclass 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");    }}
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 classesimport java.io.*; // Class 1// Helper classclass 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 classclass 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:
Related Articles:
Method Overloading and Null error in Java
Can we Overload or Override static methods in java?
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