hello everyone... I created my type which implements Comparable like public class Key implements Comparable{ ... } and i added couple of keys in my sorted set SortedSet keys = new TreeSet(); keys.add(new Key(...)); keys.add(new Key(...)); keys.add(new Key(...)); when i try to binarysearch my sorted set like Collections.binarySearch(keys, new Key()); i have error message: The method binarySearch(List extends Comparable super T>>, ...