What is the process of defining two or more methods within same class that have same name but different?

Educative Answers Team

Overloading occurs when two or more methods in one class have the same method name but different parameters.

Overriding occurs when two methods have the same method name and parameters. One of the methods is in the parent class, and the other is in the child class. Overriding allows a child class to provide the specific implementation of a method that is already present in its parent class.

The two examples below illustrate their differences:

The table below highlights their key differences:

Must have at least two methods by the same name in the class.
Must have a different number of parameters.
If the number of parameters is the same, then it must have different types of parameters.
Overloading is known as compile-time polymorphism.

Must have at least one method by the same name in both parent and child classes.
Must have the same number of parameters.
Must have the same parameter types.
Overriding is known as runtime polymorphism.

Take a look at the code below:

class Dog{

public void bark(){

System.out.println("woof ");

}

class Hound extends Dog{

public void sniff(){

System.out.println("sniff ");

}

public void bark(){

System.out.println("bowl");

}

class OverridingTest{

public static void main(String [] args){

Dog dog = new Hound();

dog.bark();

}

In this overriding example, the dog variable is declared to be a Dog. During compile-time, the compiler checks if the Dog class has the bark() method. As long as the Dog class has the bark() method, the code compiles. At run-time, a Hound is created and assigned to dog, so, it calls the bark() method of Hound.

Take a look at the code below:

class Dog{

public void bark(){

System.out.println("woof ");

}

//overloading method

public void bark(int num){

for(int i=0; i<num; i++)

System.out.println("woof ");

}

In this overloading example, the two bark methods can be invoked using different parameters. The compiler knows that they are different because they have different method signatures (method name and method parameter list).

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If a class has multiple methods having same name but parameters of the method should be different 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 to understand the behavior of the method because its name differs.

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.

Parameters should be different means
1. Type of parameter should be different

import java.io.*;
void add(int, int);
void add(double,double);
class Adder{ 
    void add(int a, int b){
        System.out.println(“sum =”+(a+b));
    } 
    void  add(double a, double b){
        System.out.println(“sum=”+(a+b));
    } 
      public static void main(String[] args){ 
        Adder ad=new Adder();
        ad.add(5,6);
        ad.add(5.4,7.2);
}}

2. Number of parameter should be different

class Adder{ 
    void add(int a, int b){
        System.out.println(“sum =”+(a+b));
    } 
      void  add(int a, int b,int c){
        System.out.println(“sum=”+(a+b+c));
    } 
      public static void main(String[] args){ 
        Adder ad=new Adder();
        ad.add(5,6);
        ad.add(5.4,7.2);
}}

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:

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.

import java.io.*;
class Addition {
    public int add(int a, int b)
    {
        int sum = a + b;
        return sum;
    }
    public int add(int a, int b, int c)
    {
        int sum = a + b + c;
        return sum;
    }
}
class GFG {
    public static void main(String[] args)
    {
        Addition ob = new Addition();
        int sum1 = ob.add(1, 2);
        System.out.println("sum of the two integer value :"
                           + sum1);
        int sum2 = ob.add(1, 2, 3);
        System.out.println(
            "sum of the three integer value :" + sum2);
    }
}

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

Method 2: By changing the Data types of the parameters

import java.io.*;
class Addition {
    public int add(int a, int b, int c)
    {
        int sum = a + b + c;
        return sum;
    }
    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);
    }
}

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

Method 3: By changing the Order of the parameters

import java.io.*;
class Geek {
    public void geekIdentity(String name, int id)
    {
        System.out.println("geekName :" + name + " "
                           + "Id :" + id);
    }
    public void geekIdentity(int id, String name)
    {
        System.out.println("Id :" + id + " "
                           + "geekName :" + name);
    }
}
class GFG {
    public static void main(String[] args)
    {
        Geek geek = new Geek();
        geek.geekIdentity("Mohit", 1);
        geek.geekIdentity(2, "shubham");
    }
}

OutputgeekName :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

import java.io.*;
class Addition {
    public int add(int a, int b)
    {
        int sum = a + b;
        return sum;
    }
    public double add(int a, int b)
    {
        double sum = a + b + 0.0;
        return sum;
    }
}
class GFG {
    public static void main(String[] args)
    {
        try {
            Addition ob = new Addition();
            int sum1 = ob.add(1, 2);
            System.out.println(
                "sum of the two integer value :" + sum1);
            int sum2 = ob.add(1, 2);
            System.out.println(
                "sum of the three integer value :" + sum2);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

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