ArrayDeque is implemented as an array, why is it not Random Access?

Question

I know that ArrayDeque is fast when adding and removing simple lists. I tested it, it was quicker to add and delete than LinkedList. Because I know that it is implemented as an Array, so why not Random Access?

I read the ArrayDeque.java file in the Java src. But I do not understand it well with my English level. I've seen a lot of articles from Google and Stack Overflow, but I did not get the answers I wanted.

In conclusion, what I'm looking for is:

1. Why is ArrayDeque not Random Access? (I am most curious)
2. In what situations is ArrayDeque used?
3. Is ArrayDeque not implemented as an Array? (Did I misunderstand this?)

Thank you very much for your reply!

Answer 1

The answer is that there's no good reason. It would be easy to add a constant-time get(int) and set(int,E) to ArrayDeque. More than once I've had to implement the algorithms of ArrayDeque within an ArrayList to make up for that lack.