Map集合根据key排序

public static void main(String[] args) {        Map<String, String> map = new TreeMap<String, String>();        map.put("d", "ddddd");        map.put("c", "ccccc");        List<Map.Entry<String, String>> list = new ArrayList<Map.Entry<String, String>>(map.entrySet());        Collections.sort(list, new Comparator<Map.Entry<String, String>>() {            public int compare(Map.Entry<String, String> o1, Map.Entry<String, String> o2) {                return o1.getValue().compareTo(o2.getValue());            }        });        String string = String.valueOf(list.get(0)) + String.valueOf(list.get(1));        System.out.println(string);    }