java Map 按value值排序和按key值排序

[code]public class Test {

    public static void main(String[] args) throws ClassNotFoundException {
        // TODO Auto-generated method stub
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("d", 2);
        map.put("c", 1);
        map.put("b", 4);
        map.put("a", 3);
        map.put("e", 5);

        List<Map.Entry<String, Integer>> list =
            new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
        for (int i = 0; i < list.size(); i++) {
            String id = list.get(i).toString();
            System.out.println(id);
        }
        System.out.println("-------------按value排序----------------------------");
        Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {   
            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {      
                return (o1.getValue() - o2.getValue()); 
            }
        }); 
        for (int i = 0; i < list.size(); i++) {
            String id = list.get(i).toString();
            System.out.println(id);
        }
        System.out.println("--------------按key排序-----------------------------");

        Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {   
            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {      
                return (o1.getKey()).toString().compareTo(o2.getKey());
            }
        });
        for (int i = 0; i < list.size(); i++) {
            String id = list.get(i).toString();
            System.out.println(id);
        }
    }
}
result：
d=2
e=5
b=4
c=1
a=3
-------------按value排序----------------------------
c=1
d=2
a=3
b=4
e=5
--------------按key排序-----------------------------
a=3
b=4
c=1
d=2
e=5