Difference Between Method Overloading and Method Overriding in Java

Understanding the difference between Method Overloading and Method Overriding in Java plays a very important role in programming. These two are the important concepts that help us to define multiple methods with the same name but different behavior, both of these are used in different situations. The main difference is in how each method is called and how Java handles it.

• Method Overloading: It occurs when we have multiple methods in the same class with the same name but have different numbers of parameters. It allows to perform operations with different inputs.
• Method Overriding: It occurs when a subclass provides a specific implementation for a method that is already defined in the superclass.

Method Overloading vs Method Overriding

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

Method Overloading in Java

Method Overloading is also known as compile-time polymorphism, which means it is a polymorphism that occurs at compile time. In method overloading, we have multiple methods in the same class with same name but each method has a different number of parameters. In method overloading the return type of these methods can be same or different, but the important thing is each method must have different number of parameters.

Key Points:

• Method overloading does not require inheritance.
• In method overloading, the return type can be the same or different, but the parameter list must differ. Changing only the return type is not method overloading.
• Method overloading improves code readability by allowing methods with similar functionality to share a name.

Example: Here, in this example mutilple methods have the same name but each method have different number of parameters.

// Demonstrating Method Overloading
import java.io.*;

class Geeks {

    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));
    }
}

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

Advantages of Method Overloading

The advantages of Method Overloading are listed below:

• It allows same methods name to be used for different operations.
• It allows us to define multiple methods with the same name but with different number of parameter
• Overloaded methods have the same name so we can easily update them in one place rather than updating them in multiple method names.

Disadvantages of Method Overloading

The disadvantages of Method Overloading are listed below:

• Too many overloaded methods with similar signatures can make the code more difficult to understand.
• Managing multiple overloaded methods with different parameters can make debugging more difficult.
• To many overloaded methods can also increase the complexity of the program

Method Overriding in Java

Method Overriding is a type of runtime polymorphism. In method overriding, a method in a derived class has the same name, return type, and parameters as a method in its parent class. The derived class provides a specific implementation for the method that is already defined in the parent class.

Key Points:

• Method Overriding requires inheritance.
• In method overriding, method signature including name and parameter must match exactly.
• In method overriding, return type must be same.
• In method overriding, private and final methods can not be overridden.
• @Override annotation ensures correct overriding.

Example: Here, in this example polymorphism allows calling the subclass method through a parent class reference.

// Demonstrating method overriding 
// and polymorphism 
import java.io.*;

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

// Derived Class
class Dog extends Animal {
    @Override
    void eat() {
        System.out.println("eat() method of derived class");
        System.out.println("Dog is eating.");
    }
    
    // Method to call the base class method
    void eatAsAnimal() {
        super.eat();
    }
}

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

        // Calls the eat() method of Dog class
        d1.eat();
        
        // Calls the eat() method of Animal class
        a1.eat();

        // Polymorphism: Animal reference pointing to Dog object
        Animal animal = new Dog();
        
        // Calls the eat() method of Dog class
        animal.eat();
        
        // To call the base class method, you need to use a Dog reference
        ((Dog) animal).eatAsAnimal();
    }
}

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

Explanation:

Here, we can see that a method eat() has overridden in the derived class named Dog that is already provided by the base class named 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(). 

Advantages of Method Overriding

The advantages of Method Overriding are listed below:

• It allows for dynamic method dispatch which enhance the flexibility.
• It allows changes to specific class behaviors without changing the entire class hierarchy.
• We can easily extend classes and modify behaviors without altering the parent class.

Disadvantages of Method Overriding

The disadvantages of Method Overriding are listed below:

• Overriding methods can make the code more complex in large inheritance hierarchies.
• It is only useful in inheritance, it is not applicable for all design situation.
• Overriding methods can also lead to unintentional behavior changes.