TreeMap高低键整数排序

Question

    Map<Integer, String> map = new TreeMap<Integer, String>();

    // Add Items to the TreeMap
    map.put(new Integer(8), "Eight");
    map.put(new Integer(9), "Nine");
    map.put(new Integer(1), "One");
    map.put(new Integer(4), "Four");
    map.put(new Integer(10), "Ten");
    map.put(new Integer(5), "Five");
    map.put(new Integer(6), "Six");
    map.put(new Integer(2), "Two");
    map.put(new Integer(3), "Three");
    map.put(new Integer(7), "Seven");

    keys = map.keySet();
    for (Iterator i = keys.iterator(); i.hasNext();) {
      Integer key = (Integer) i.next();
      String value = (String) map.get(key);
      System.out.println(key + " = " + value);
    }

输出:

• 1 =一个
• 2 =两个
• 3 =三
• 4 =四
• 5 =五
• 7 =七
• 8 =八
• 9 =九
• 10 =十

我想颠倒TreeMap的整数排序,所以最高整数将在前面,最低和最后,我怎么能完成这个？提前致谢.

Answer 1

TreeMap的构造函数可以带Comparator你通过自定义实现

更改Map声明以传递逆序比较器

Map<Integer, String> map = new TreeMap<Integer, String>(Collections.reverseOrder());

另见

• 使用Java对点列表进行排序