Brownies Collections complements the Java Collections Framework. GapList combines the strengths of both ArrayList and LinkedList. BigList is a list optimized for storing large number of elements. There are specialized List implementations for all primitive data types (IntGapList, IntBigList, IntObjGapList, IntObjBigList). The key collection classes offer support for keys and constraints for lists and collections (KeyList, KeyCollection, KeySet, Key1List, Key1Collection, Key1Set, Key2List, Key2Collection, Key2Set).