30 Important Java Collections API Interview Q & A's

Posted in: Java Collections

1. Explain about Java Collections API?

2. What is an Iterator interface?

3. What is listiterator in java?

4. What is the difference between Iterator and ListIterator?

5. what is Enumeration in java?

6. What is difference between Iterator and Enumeration?

7. Explain About Collections class in java?

8. What is the Set interface?

9. What is hashset in java?

10. What is TreeSet in java?

11. Difference between HashSet and TreeSet?

12. Can a null element added to a Treeset or HashSet?

13. What is the List interface?

14. What is the difference between a Set and a List?

15. What is Arraylist in Java?

16. Explain about Vector in java?

17. Difference between Vector and ArrayList?

18. How can Arraylist be synchronized without using Vector?

19. Explain about Map interface in Java?

20. What is SortedMap in Java?

21. Explain about WeakHashMap class in java?

22. What is the Hastable class in java?

23. What is the Hashmap Class in Java?

24. Difference between Hashtable and HashMap?

25. When will you use Hashtable and When will you use HashMap?

26. Is it better to have a HashMap with large number of records or 'n' number of small hashMaps?

27. What is the difference between a Stack and LinkedList in Java?

28. What is difference between array and arraylist in java?

29. What is difference between iterator access and index access?

30. What is identityHashMap in Java?