java按照map的value排序

java按照map的value排序

分类： java 2012-08-26 20:37  4843人阅读  评论(0)  收藏  举报

java integer iterator exception application 算法

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 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> list = new ArrayList>(oldMap.entrySet());
         Collections.sort(list, new Comparator>() {

             @Override
             public int compare(Entry arg0,
                     Entry 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;
     }
 }