What is Method Overloading and Method Overriding in Java?

Method Overloading and Method Overriding are two core concepts of Polymorphism in Java. The key difference is that overloading occurs at compile-time (static polymorphism), while overriding occurs at runtime (dynamic polymorphism).

1. Method Overloading (Compile-Time Polymorphism)

Multiple methods in the same class share the same name but have different parameters (number, type, or order).

class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
    
    public int add(int a, int b, int c) {
        return a + b + c;
    }
    
    public double add(double a, double b) {
        return a + b;
    }
    
    public static void main(String[] args) {
        Calculator calc = new Calculator();
        System.out.println(calc.add(5, 10));      // Output: 15
        System.out.println(calc.add(5, 10, 15));  // Output: 30
        System.out.println(calc.add(5.5, 2.5));   // Output: 8.0
    }
}

2. Method Overriding (Runtime Polymorphism)

A child class provides a specific implementation of a method already defined in its parent class.

class Animal {
    public void sound() {
        System.out.println("Animal makes a sound");
    }
}

class Dog extends Animal {
    @Override
    public void sound() {
        System.out.println("Dog barks");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal myDog = new Dog();
        myDog.sound();    // Output: Dog barks
    }
}

Key Differences

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