DCA - TCS Digital Interview Questions 2025

DCA Interview

1. What is the difference between JDK, JRE, and JVM?
2. What is the use of the transient keyword in Java?
3. How do you handle exceptions in Java?
4. What is the difference between an abstract class and an interface in Java?
5. Can you explain the concept of polymorphism in Java?
6. What is the difference between overloading and overriding in Java?
7. What is a constructor in Java and what is its purpose?
8. What is the difference between static and non-static methods in Java?
9. What is a package in Java?
10. What is the difference between private, protected, and public access modifiers in Java?
11. What is the purpose of the final keyword in Java?
12. What is a static block in Java and what is its purpose?
13. What is the difference between final, finally, and finalize in Java?
14. What is a thread in Java and how do you create one?
15. What is the difference between a process and a thread in Java?
16. How do you synchronize threads in Java?
17. What is a synchronized method in Java and how does it work?
18. What is the difference between ArrayList and LinkedList in Java?
19. What is a HashMap in Java and how does it work?
20. What is the difference between an iterator and a list iterator in Java?
21. What is the difference between a HashSet and a TreeSet in Java?
22. What is a StringBuilder in Java and how does it differ from a StringBuffer?
23. What is a lambda expression in Java?
24. What is the difference between functional and imperative programming in Java?
25. What is the difference between a stream and a collection in Java?
26. What is the purpose of the Optional class in Java?
27. What is a functional interface in Java?
28. What is a default method in Java?
29. What is a static method in an interface in Java?
30. What is the difference between the comparable and comparator interfaces in Java?
31. What is a reflection in Java and how does it work?
32. What is the difference between an annotation and a comment in Java?
33. What is a type erasure in Java?
34. What is a diamond operator in Java?
35. What is a try-with-resources statement in Java and how does it work?
36. What is a marker interface in Java?
37. What is the difference between shallow and deep copying in Java?
38. What is the difference between a pass-by-value and a pass-by-reference in Java?
39. What is a memory leak in Java?
40. What is a JVM heap and how does it work?