Is there a longer than int Java List?

Question

I can\'t seem to find a Java List that\'s max length is long\'s max value.

Does such a List exist?

If so, where?

Answer 1

As @afsantos says, the ArrayList class is inherently limited to Integer.MAX_VALUE entries because of the limitations of Java arrays.

LinkedList doesn't have this limitation, but it is (nonetheless) expensive:

• Each entry incurs an memory overhead of 2 references plus the size of an object header ... compared to just one reference for an array-based representation.

• Indexing is an O(N) operation compared with O(1) for an array-based list.

Here is a link to Java library that supports huge in-memory collections using direct mapped memory and/or encoding of the elements:

• http://code.google.com/p/vanilla-java/wiki/HugeCollections

There could be other alternatives out there.

One could also envisage a "big" variant of regular array lists that used an array of arrays rather than a single array. But if you allow insertion into the middle of the list, it becomes difficult / expensive to achieve O(1) lookup. (That might be why I couldn't find an example with Google ...)