Re: Lists of size Integer.MAX_VALUE

Piotr Kobzda <>
Mon, 09 Jul 2007 16:57:08 +0200
Piotr Kobzda wrote:

Lew wrote:

Suppose we have a List 'someList' containing exactly Integer.MAX_VALUE
elements and we
  someList.add( element );
  someList.add( Integer.MAX_VALUE, element );

According to the Javadocs, this is legal, but how then could we
reference the last element of the list?


Of course, it requires the implementation of ListIterator which don't
fully support its interface (in particular previousIndex()/nextIndex()
methods cannot be fully supported).

Safer approach (in terms of achieving working solution) would be:

   lastElement = null;
   for(Iterator it = someList.iterator();
       it.hasNext(); lastElement =;

But it's poor from the performance point of view...

In fact, the same performance problem applies to the ListLterator's use
(a list must be a bit bigger only to observe that, for example
2*Integer.MAX_VALUE, or more, elements...).

So, currently defined List interface disallows the efficient working
with a "large lists" IMHO.

Some additional methods are needed to support that, for example a list
implementing the following interface would be better:

   public interface LargeList<T> extends List<T> {
     /** Returns a view of the portion of this list between the
specified fromIndex, inclusive, and this list's last element, inclusive. */
     List<T> subList(int fromIndex);

Unfortunately, most of the current uses of lists assumes that a maximum
list size is Integer.MAX_VALUE, so the above-like large list won't work
as expected with other libraries (e.g. Collections.reverse() is useless
with such a list...).

Conclusion: large lists are impractical.


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