Working with End Points : TreeMap « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. TreeMap

The firstKey() and lastKey() methods of TreeMap let you quickly access the keys at the end of the map.

If you need to traverse a map backwards(keep getting the last key and the head map before it):

import java.util.TreeMap;

public class MainClass {
  public static void main(String[] a) {

    TreeMap map = new TreeMap();
    map.put("key1", "value1");
    map.put("key2", "value2");
    map.put("key3", "value3");

    if (!map.isEmpty()) {
      Object last = map.lastKey();
      boolean first = true;
      do {
        if (!first) {
          System.out.print(", ");
        }
        System.out.print(last);
        last = map.headMap(last).lastKey();
        first = false;
      } while (last != map.firstKey());
      System.out.println();
    }
  }
}

key3, key2