Java - Collection

Question

I got a question regarding what type of collection class should i used based on the scenario given but i am not sure whether i am correct?
Can any1 correct me if i am wrong.
1. When a hotel is fully booked, it holds a waiting list of customers in case of
cancellations. Once a cancellation is received, the newly available room is allocated
to the first person on the waiting list, who is then deleted from the list. On a
particular day the first three customers added to the list are Ali Baba, Bibi Batek and
Charlie Chan.
class used : HashSet
2. A video shop wants to store the titles of videos available for hire. It must be possible
to list all the titles available but no particular order is required. Although the store
may have more than one copy of a particular film, the title should only appear once.
Titles available include: Iron Man, Crystal Skull and Dr Doplenty.
class used : Collection - ArrayList
3. An ICT203 tutor wants to store her students' myUniSIM names as strings in such a
way that she can easily look up an individual student, as in the table below. There are
no two students in her group with the same name.
Student’s name myUniSIM name
Charlie Dickens Charles Dickens
Margie Hector Margaret Hector
Terry Martin Terence Martin
class used : HashMap

Answer 1

Hi,
this sounds to me as if you just received some homework and you made a more or less blind guess?
I suggest you first take a good look at the JavaDoc for each of the Collection classes you mentioned, because just as a starter: the HashSet you suggest for your first question provides no way of returning elements in any particular order. This is obvious from the JavaDoc showing no getFirst() or whatsoever, only an iterator()-Method, but this method is documented as follows:
public Iterator<E> iterator()
Returns an iterator over the elements in this set. The elements are returned in no particular order.
So please, read the docs available and make up your mind again.
Bye.