Java OOP

⏷ 1. What are the four pillars of OOP? Explain each with examples.

⏷ 2. What is the difference between a class and an object?

⏷ 3. What happens if you declare a class as final? Can it still have objects?

⏷ 4. What happens if an object is created inside a static method?

⏷ 5. How does the this keyword differ from super?

⏷ 6. Can a constructor be inherited in Java? Why or why not?

⏷ 7. What happens if a subclass overrides a method but calls the super version as well?

⏷ 8. Can a subclass call a private method of the superclass?

⏷ 9. What is polymorphism, and how does it work in Java?

⏷ 10. Can you override a static method in Java?

⏷ 11. How does Java handle method overloading when the arguments involve inheritance (e.g., Object vs. String)?

⏷ 12. How does Java decide which overridden method to call when the reference type and object type differ?

⏷ 13. What is abstraction, and how is it implemented in Java?

⏷ 14. How do default methods in interfaces affect abstraction in Java 8+?

⏷ 15. Can an abstract class have a constructor, and when is it called?

⏷ 16. How does encapsulation improve code maintainability?

⏷ 17. Why should instance variables in a class be private?

⏷ 18. Can you enforce encapsulation without getters and setters?

⏷ 19. Can you enforce encapsulation without getters and setters?

⏷ 20. How does Java handle the diamond problem in interfaces?

⏷ 21. Can an interface extend another interface and how is it useful?

⏷ 22. Can an interface contain static methods? How are they accessed?

⏷ 23. What is the difference between composition and aggregation?

⏷ 24. How is dependency injection related to composition?

⏷ 25. What happens if a constructor calls another constructor using this() and has code before the call?

⏷ 26. Can a constructor throw an exception? How would you handle it?

⏷ 27. What happens if a subclass doesn’t explicitly call a superclass constructor?

⏷ 28. What is the difference between method overloading and method overriding?

⏷ 29. Can you override a private method in Java?

⏷ 30. Can a method with throws clause in the superclass be overridden without it in the subclass?

⏷ 31. What is the SOLID principle in OOP?

⏷ 32. How does the Single Responsibility Principle help in writing maintainable code?

⏷ 33. Can you explain the Open/Closed Principle with an example?

⏷ 34. How do Liskov Substitution and Interface Segregation principles influence your choice of inheritance or interfaces?

⏷ 35. How can you ensure a method follows the Dependency Inversion Principle?