Affects Version/s: None
Fix Version/s: None
All known implementations of List are all have O( n ) for indexOf() operation.
Here is my implementation of such List on github which has O(log n) for indexOf() and contains():
There are two modifications: one implements both List and Set, so it can contains unique elements, second modification can contains any amount of unique objects, but it's a bit slower.
It's based on TreeList and provide complexity:
- get by index is O(log n)
- insertion, removing (both by index or by value) are O((log n) * (1 + log m)) where is amount of elements equals to inserted/removed element.
- insertion, removing are O(log n) if all elements are unique.
- indexOf and lastIndexOf are O(log n).
- contains is O(1) or (log n) depending on Map implementation.
As those collections have complexity similar to TreeSet (at least in cases of unique elements), overall performance is 20-30% slower due to element indexing and eliminating some optimizations. However it provides fast indexOf and contains.
Can I help in porting my code to Apache common Collections library?