Big-O complexity of java.util.stream.Stream.sorted()

Question

Does anyone know what the time complexity of java.util.stream.Stream.sorted() is?

Answer 1

As of JDK 8, the main sorting algorithm which is also used in standard stream API implementation for sequential sorting is TimSort. Its worst case is O(n log n), but it works incredibly fast (with O(n) and quite small constant) if data is presorted (in forward or reverse direction) or partially presorted (for example, if you concatenate two sorted lists and sort them again).