DCA - TCS Digital Interview Questions 2025

DCA Interview

1. What is OOPs and what are the four principles of OOPs?
2. What is inheritance in OOPs and how is it implemented in Java?
3. What is polymorphism in OOPs and how is it implemented in Java?
4. What is encapsulation in OOPs and how is it implemented in Java?
5. What is abstraction in OOPs and how is it implemented in Java?
6. What is the difference between an abstract class and an interface in OOPs?
7. What is the difference between composition and inheritance in OOPs?
8. What is method overloading and method overriding in OOPs?
9. What is the difference between method overloading and method overriding in OOPs?
10. What is the difference between an object and a class in OOPs?
11. What is the purpose of the static keyword in OOPs?
12. What is the difference between a static method and a non-static method in OOPs?
13. What is a constructor in OOPs and what is its purpose?
14. What is the difference between a constructor and a method in OOPs?
15. What is the purpose of the final keyword in OOPs?
16. What is the purpose of the abstract keyword in OOPs?
17. What is the difference between an interface and a class in OOPs?
18. What is a package in OOPs and how is it used in Java?
19. What is the purpose of the super keyword in OOPs?
20. What is the difference between private, protected, and public access modifiers in OOPs?
21. What is a static block in OOPs and what is its purpose?
22. What is a singleton class in OOPs and how is it implemented in Java?
23. What is a factory pattern in OOPs and how is it implemented in Java?
24. What is the difference between a stack and a queue in OOPs?
25. What is the difference between a linked list and an array in OOPs?
26. What is the difference between a hash table and a hash map in OOPs?
27. What is the purpose of the this keyword in OOPs?
28. What is a virtual method in OOPs?
29. What is a reference variable in OOPs and how is it used in Java?
30. What is the purpose of the instanceof operator in OOPs?