java按照map的value排序 转载http://blog.csdn.net/tsingheng/article/details/7909861

java的TreeMap可以排序，只可惜是按照key来排序的，或者重写其他Map的排序算法也都是按照key来排序的，下面贴出来一个按照value排序的算法：

 

public class SortMap {
    public static void main(String[] args) throws Exception {
        // TODO code application logic here
        Map<String, Integer> myMap = new LinkedHashMap();
        myMap.put("1", 1);
        myMap.put("2", 4);
        myMap.put("3", 3);
        myMap.put("4", 9);
        myMap.put("5", 6);
        myMap.put("6", 2);

        printMap(myMap);

        myMap = sortMap(myMap);

        printMap(myMap);
    }

    private static void printMap(Map map){
        System.out.println("===================mapStart==================");
        Iterator it = map.entrySet().iterator();
        while(it.hasNext()){
            Map.Entry entry = (Map.Entry) it.next();
            System.out.println(entry.getKey() + ":" + entry.getValue());
        }
        System.out.println("===================mapEnd==================");
    }

    public static Map sortMap(Map oldMap) {
        ArrayList<Map.Entry<String, Integer>> list = new ArrayList<Map.Entry<String, Integer>>(oldMap.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {

            @Override
            public int compare(Entry<java.lang.String, Integer> arg0,
                    Entry<java.lang.String, Integer> arg1) {
                return arg0.getValue() - arg1.getValue();
            }
        });
        Map newMap = new LinkedHashMap();
        for (int i = 0; i < list.size(); i++) {
            newMap.put(list.get(i).getKey(), list.get(i).getValue());
        }
        return newMap;
    }
}