降序排序

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;


public class mapSort {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Map<String,String> map = new HashMap<String,String>();
//        map.put("c","cccc");
//        map.put("a","aaaa");
//        map.put("b","bbbb");
//        map.put("d","dddd");
        map.put("c","0.6");
        map.put("a","0.78");
        map.put("b","0.5");
        map.put("d","0.78");
        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(Entry<String,String> o1,Entry<String,String> o2){
                return o2.getValue().compareTo(o1.getValue());
            }
        }
        );
//        for(Map.Entry<String, String> mapping:list){
//          System.out.println(mapping.getKey()+":"+mapping.getValue());
//        }
       // for(int i = 0;i<1;i++)
        for(int i = 0;i<list.size();i++)
        {
            System.out.println("key:" + list.get(i).getKey() + "---Value:" + list.get(i).getValue() );
              }
    }


}

运行结果

升序排序，只需改一行

public int compare(Entry<String,String> o1,Entry<String,String> o2){
                return o1.getValue().compareTo(o2.getValue());
            }

运行结果