Collection question(difference in some methods)

Question

Good evening,
when we have a collection(whatever collection is that) what's the general difference between the method size() and capacity(),i mean which size do the return?
Also,whats the difference between remove and retrieve?
Thanks,in aadvance!

Answer 1

Thank you very much,i understood it now :)
1) I saw the constructor of HashTable(int initial
capacity,float LoadFactor)
what is this load factor?I'm pretty sure the docs explain it, but I think it's how much of its capacity the hashtable will use up before it allocates more buckets and rehashes.
If you don't understand what that means or why it matters, start here (the Table Resizing bit is what's relevant), and google for more info on hashing if needed: http://en.wikipedia.org/wiki/Hashtable
Again, it's one of those things that you can tweak if you need to, but you usually don't need to.
2)Also,a clone method only copies a collection and
returns an object of the collection?It creates a new collection. That collection has its own references to the same elements as the orignal. The elements themselves are not duplicated.
3)we use a constructor to make a new collection e.g.
List hey = new List();
this command takes O(n) time or O(nlogn) time?Well, you can't do new List(), since List is an interface.
If you mean, for example, new ArrayList(), then that's O(1), or possibly O(capacity).
If you mean, for example, new ArrayList(existingCollection), then it's O(n), where n is the size of the existing collection. You have to copy each reference.