List to Array with Type

Question

Hi guys,
I need to turn a List (an ArrayList specifically) into an array of Components.
This is because I can't call a function like doSomething(Component ... components) with a collection. It needs to be an array correct?
So, if it needs to be an array, I can't find a clean way to do it....or maybe I'm just a whiner.
I can do this with
theList.toArray(new Component[theList.size()]);or I can do it with
(Component[])theList.toArray()But I don't like either of those...why should I have to pass an array in the first one and why should I be the one doing the cast in the second one?
Shouldn't the ArrayList know how to return a correctly typed array?
I wrote this little static method that I put in a helper class...does anything like this exist in the Collections class as a static method?
I couldn't find anything like it in Arrays, or Collections etc.
public static <T> T[] collectionToArray(Collection<T> l){
    Object ret[] = new Object[l.size()];
    int i = 0;
    for(T t : l){
        ret[i++] = t;
    return (T[]) ret;
}If there is a better way to do this please let me know.
Thanks,
~Eric

Answer 1

ganeshmb wrote:
It wasn't done because you either need an array of the proper type passed as a parameter, or a Class<T> passed as a parameter.Why? ArrayList is parametrized, which means it should be able to figure the data type by inspecting its contents, right? The only problem I see is, when its contents are empty, it will have to return null instead of an empty array. This is a different behavior from toArray, but should be acceptabe given the ease of use for clients - they don't have to pass an array instance to get the list back as an array.Wrong. In addition to the empty array behavior, suppose I have an List<Map>. I could have HashMap, ConcurrentHashMap, Properties, etc, all in this list. I still want a Map[] returned. What if my list is filled with HashMap? I still want a Map[] returned. Inspecting the contents is not a workable solution.