Java tutorial
import java.util.NavigableMap; import java.util.TreeMap; public class Main { public static void main(String[] args) { NavigableMap<Integer, String> map = new TreeMap<Integer, String>(); map.put(2, "two"); map.put(1, "one"); map.put(3, "three"); System.out.println(map.descendingKeySet() + "\n"); } }