Which data structure to use?

[malaguena]

Hello,

I need a data structure which:

1) I will be able to remove an item (without knowing the index of that item)
2) I can draw an item randomly (normally in an array, I generate a random number and draw that item in that index.. data structures that use keys -hashtables, hashmaps vs need an iterator to go through the items)
3) I will be able to add an item (the adding order does not matter)

Which data structure gives faster solutions?

Thanks..

[FlipPoker@gmail.com]

HashSet can do all of those things. For #2, you have to use the toArray() method, though.

[malaguena]

Good idea. Have you got any idea about the performance of converting a HashSet to an array?

Thanks for the reply.

[FlipPoker@gmail.com]

I'm sorry, I don't know the answer to that. I'm guessing it would be O(N), since you have to move the elements one by one. But I'm not sure.

[malaguena]

Yes, it should depend on the size of the HashSet, I guess.
Thanks again.