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Top 50 Interview questions and answers on Java Collections Framework
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1. What is the difference between List and Set?
2. Explain the difference between Comparator and Comparable
3. What happens when you insert a null key into a HashMap?
4. What is the difference between clone() and copyOf() in collections?
5. What is a SortedMap, and how does it work?
6. What is a weakHashMap, and when would you use it?
7. How do you implement a queue using the Collections Framework?
8. Explain the concept of ConcurrentHashMap.
9. How can you check if two collections are equal?
10. How do you create an immutable list in Java?
11. List the main interfaces in the Java Collections Framework.
12. What is a LinkedHashSet, and how does it differ from HashSet?
13. How can you synchronize a List in Java?
14. How can you find the intersection of two Sets?
15. How do you sort a Set using a custom comparator?
16. What is the difference between remove() and clear() in collections?
17. How do you convert an ArrayList to an array?
18. How does the contains() method work in a Set?
19. What is the difference between shallow copy and deep copy in collections?
20. What are the characteristics of a Stack in Java?
21. Explain the purpose of the Deque interface.
22. Explain the difference between toArray() and toArray([]).
23. What is a Navigableset and how does it extend. SortedSet?
24. What is a priority queue, and how is it different from a regular queue?
25. How does LinkedHashMap maintain insertion order?
26. How do you remove duplicates from a List?
27. What is the difference between HashSet and TreeSet?
28. What is the difference between subList() and slice()?
29. What are the key differences between List and Queue?
30. What is the difference between ArrayList and LinkedList?
31. How can you iterate over a Map in Java?
32. What are the performance implications of using different collection types?
33. What is the purpose of the Map interface?
34. What is the load factor in HashMap?
35. What is the Stream API, and how does it relate to collections?
36. What are the advantages of using a TreeSet over a HashSet?
37. What is the difference between Collection and Collections?
38. What is fail-fast behavior in Java Collections?
39. What are the different ways to traverse a List?
40. What is the purpose of the Collections utility class?
41. Explain the difference between HashMap and Hashtable
42. What is the significance of the retainAll() method?
43. How does HashMap work internally?
44. What is the Java Collections Framework?
45. Explain the differences between Iterator and ListIterator.
46. What is the difference between Collections.sort() and List.sort()?
47. Explain the concept of a Map. Entry in a HashMap
48. What is the difference between a List and an Array?
49. Explain the poll() and remove() methods in the Queue interface.
50. What is the difference between a HashMap and a TreeMap?