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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