Vector or ArrayList use for dropdown with more than 1000 entries

[vikram karne]

Hi Friends

I am having more than 1000 entries of different TimeZone's which i need to display in a dropdown list.
i am not able to decide whether i need to use a Vector or Arraylist for storing these values.
please let me know which one will be best suited to use in case the list entry is more than 1000 characters.
waiting for a positive reply from your side.

Thanks & Regards
Vikeng

[Gavin Tranter]

I would chose the ArrayList, Vector is part of thw older original collections, and is thread safty, however, ArrayList is part of the current collection frame work, but isint thread safe, so it is "quicker".

I dont remember much about drop downs, I havent used them in awhile, but if you know what the Timezones are in advance, how many there are of them, and they arent going to change, I wonder if an array of Timezones would not be better?

[Jesper de Jong]

You are most likely not going to notice any performance difference at all between Vector and ArrayList.

However, I would use ArrayList simply because Vector is an old, legacy collection class for which there is no good reason to use it anymore at all.

[Ernest Friedman-Hill]

Do you really need to inflict a 1000-entry dropdown list on your users? Surely you can think of a better UI: divide the timezones up by region, for example, and display only those for the current region. Or use an input field with typeahead-suggest? Or a map to click on?

[Maneesh Godbole]

Think MVC.
You dont really need to populate the values all the values in a vector and then pass them to the JList (I am presuming its a JList as you mentioned drop down).
You need to tweak the following two methods:

 
public int getSize() and   
public Object getElementAt(int index)

Check out the JList API which cites a concrete example.

[vikram karne]

Thank you all for your replies

Finally i have set all the values in the ArrayList as all of you suggested.
it works for now but need to see the performance issue in the longer run for such a huge list of values.

Thanks a lot once again

Regards
Vikram K

[Tony Docherty]

Originally posted by vikram karne:
but need to see the performance issue in the longer run for such a huge list of values.

You don't need to worry about the performance of the code so much as the performance of the user. As Ernest has already said, requiring a user to search through 1000 items to find the one item they want is not at all user friendly and will be where any performance bottleneck is to be found. Even if it takes a 1 or 2 seconds to populate the list this will be insignificant compared to the minutes it's likely to take the user to find the correct choice.

[Nicholas Jordan]

[Tony Docherty:]You don't need to worry about the performance of the code so much as the performance of the user.

Yes, as you state, the advice of EFH and Jesper Young should be given immediate work by the original poster. This approach may not be easy to find on first attempt to solve this design challenge.

Author vikram karne would likely make better progress if one of the Collections has a getInterval(int beginGettingItems, int endOfInterval) method, and it does.

    /**
     * Returns a view of the portion of this list between the specified
     * fromIndex, inclusive, and toIndex, exclusive.  (If
     * fromIndex and toIndex are equal, the returned list is
     * empty.)  The returned list is backed by this list, so non-structural
     * changes in the returned list are reflected in this list, and vice-versa.
     * The returned list supports all of the optional list operations supported
     * by this list.
     *
     * This method eliminates the need for explicit range operations (of
     * the sort that commonly exist for arrays).   Any operation that expects
     * a list can be used as a range operation by passing a subList view
     * instead of a whole list.  For example, the following idiom
     * removes a range of elements from a list:
     * 
     *      list.subList(from, to).clear();
     * 
     * Similar idioms may be constructed for indexOf and
     * lastIndexOf, and all of the algorithms in the
     * Collections class can be applied to a subList.
     *
     */
    List subList(int fromIndex, int toIndex);

The Collections are all well suited to use in case, it is in fact a GUI issue we actually have here.