Difference Between Method Overloading and Method Overriding in Java

The differences between Method Overloading and Method Overriding in Java are as follows:

Method Overloading	Method Overriding
Method overloading is a compile-time polymorphism.	Method overriding is a run-time polymorphism.
Method overloading helps to increase the readability of the program.	Method overriding is used to grant the specific implementation of the method which is already provided by its parent class or superclass.
It occurs within the class.	It is performed in two classes with inheritance relationships.
Method overloading may or may not require inheritance.	Method overriding always needs inheritance.
In method overloading, methods must have the same name and different signatures.	In method overriding, methods must have the same name and same signature.
In method overloading, the return type can or can not be the same, but we just have to change the parameter.	In method overriding, the return type must be the same or co-variant.
Static binding is being used for overloaded methods.	Dynamic binding is being used for overriding methods.
Poor Performance due to compile time polymorphism.	It gives better performance. The reason behind this is that the binding of overridden methods is being done at runtime.
Private and final methods can be overloaded.	Private and final methods can’t be overridden.
The argument list should be different while doing method overloading.	The argument list should be the same in method overriding.

Method Overloading in Java

Method Overloading is a Compile time polymorphism. In method overloading, more than one method shares the same method name with a different signature in the class. In method overloading, the return type can or can not be the same, but we have to change the parameter because, in java, we can not achieve method overloading by changing only the return type of the method. 

Example of Method Overloading:

Java

// Java Program to Implement
// Method Overloading
import java.io.*;

class MethodOverloadingEx {

    static int add(int a, int b) { return a + b; }

    static int add(int a, int b, int c)
    {
        return a + b + c;
    }

    // Main Function
    public static void main(String args[])
    {
        System.out.println("add() with 2 parameters");
        // Calling function with 2 parameters
        System.out.println(add(4, 6));

        System.out.println("add() with 3 parameters");
        // Calling function with 3 Parameters
        System.out.println(add(4, 6, 7));
    }
}

Output

add() with 2 parameters
10
add() with 3 parameters
17

Method Overriding in Java

Method Overriding is a Run time polymorphism. In method overriding, the derived class provides the specific implementation of the method that is already provided by the base class or parent class. In method overriding, the return type must be the same or co-variant (return type may vary in the same direction as the derived class). 

Example of Method Overriding:

Java

// Java Program to implement
// Method Overriding
import java.io.*;

// Base Class
class Animal {
    void eat()
    {
        System.out.println("eat() method of base class");
        System.out.println("eating.");
    }
}

// Inherited Class
class Dog extends Animal {
    void eat()
    {
        System.out.println("eat() method of derived class");
        System.out.println("Dog is eating.");
    }
}

class MethodOverridingEx {
    // Main Function
    public static void main(String args[])
    {
        Dog d1 = new Dog();
        Animal a1 = new Animal();

        d1.eat();
        a1.eat();

        Animal animal = new Dog();
        // eat() method of animal class is overridden by
        // base class eat()
        animal.eat();
    }
}

Output

eat() method of derived class
Dog is eating.
eat() method of base class
eating.
eat() method of derived class
Dog is eating.

Output explanation: Here, we can see that a method eat() has overridden in the derived class name Dog that is already provided by the base class name Animal. When we create the instance of class Dog and call the eat() method, we see that only derived class eat() method run instead of base class method eat(), and When we create the instance of class Animal and call the eat() method, we see that only base class eat() method run instead of derived class method eat().