Explain method overloading and method overriding in Java

💡 Concept: Method Overloading and Overriding

Method overloading allows multiple methods in the same class with the same name but different parameters. Method overriding allows a subclass to provide a specific implementation of a method already defined in its superclass.

📘 Quick Intro

Overloading is compile-time polymorphism; overriding is runtime polymorphism, essential for flexibility and code reuse.

🧠 Analogy

Overloading is like having multiple phone numbers for different purposes; overriding is like answering the phone differently depending on who is calling.

🔧 Technical Explanation

Method overloading: Same method name, different parameter list within a class.
Method overriding: Subclass method with same signature as superclass method.
Overloading happens at compile-time; overriding at runtime.
Overriding requires inheritance.
Overriding supports dynamic method dispatch and polymorphism.

🎯 Use Cases

✅ Use overloading to increase method flexibility.
✅ Use overriding to change or extend behavior in subclasses.
✅ Essential for designing polymorphic systems.

💻 Java Code Example


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

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

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

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

public class Main {
    public static void main(String[] args) {
        Calculator calc = new Calculator();
        System.out.println(calc.add(2,3));     // 5
        System.out.println(calc.add(2,3,4));   // 9

        Animal a = new Dog();
        a.sound();  // Dog barks
    }
}

❓ Interview Q&A

Q1: What is method overloading?
A: Multiple methods with same name but different parameters.

Q2: What is method overriding?
A: Subclass provides specific implementation of superclass method.

Q3: Which polymorphism is overloading?
A: Compile-time polymorphism.

Q4: Which polymorphism is overriding?
A: Runtime polymorphism.

Q5: Does overriding require inheritance?
A: Yes.

Q6: Can private methods be overridden?
A: No.

Q7: Can static methods be overridden?
A: No, they are hidden not overridden.

Q8: What is dynamic method dispatch?
A: Runtime decision to invoke overridden method.

Q9: Can constructors be overloaded?
A: Yes.

Q10: Can method overloading occur across classes?
A: No, only within the same class.

📝 MCQs

Q1. What is method overloading?

Different method names
Multiple methods with same name but different parameters
Abstract methods
Static methods

Q2. What is method overriding?

Overloading
Subclass implementation of superclass method
Interface implementation
Constructor overloading

Q3. Which polymorphism is compile-time?

Method overriding
Method overloading
Dynamic dispatch
Inheritance

Q4. Which polymorphism is runtime?

Method overloading
Method overriding
Static dispatch
Dynamic typing

Q5. Does overriding require inheritance?

No
Yes
Sometimes
Never

Q6. Can private methods be overridden?

Yes
No
Sometimes
Only public

Q7. Can static methods be overridden?

Yes
No
Sometimes
Depends

Q8. What is dynamic method dispatch?

Compile-time binding
Runtime decision to invoke overridden method
Static dispatch
Method hiding

Q9. Can constructors be overloaded?

No
Yes
Sometimes
Never

Q10. Can method overloading occur across classes?

Yes
No
Sometimes
Only with inheritance

💡 Bonus Insight

Understanding overloading and overriding is crucial for mastering Java polymorphism and writing flexible code.

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