Java-Collections

1-Which of these is not a interface in the Collections Framework?

2-Which interface restricts duplicate elements?

3-Which of these collection class has the ability to grow dynamically?

4-What implementation of Iterator can traverse a collection in both directions?

5-Which of these is synchronized?

6-Which does not allow to store a null value?

7-Which is best suited to a multi-threaded environment?

8-The default capacity of a ArrayList is:

9-Which provides better performance for the insertion and removal from the middle of the list?

10-Which of these allows the storage of many null values?