将Map按其value进行降序排序

由于Map中的TreeMap只能按key排序，本文中实现了通过Collections工具类及comparator接口实现Map按value排序

package me;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

/**

* 将Map中的Entry按照value的降序排序

*

* @author:TuGh,WangM

*/

public class TreeMapTest {

public static void main(String[] args) {

Map<Integer,Double> map =new LinkedHashMap<Integer,Double>();

map.put(5, 100.0);

map.put(1, 2.0);

map.put(2, 5.0);

map.put(3, 2.0);

map.put(4, 4.0);

System.out.println(map.entrySet());

List<Map.Entry<Integer, Double>> list = new ArrayList<Map.Entry<Integer, Double>>(map.entrySet());

//使用Collections工具类对list进行排序

Collections.sort(list, new Comparator<Map.Entry<Integer, Double>>() {

@Override

public int compare(Entry<Integer, Double> o1, Entry<Integer, Double> o2) {

// TODO Auto-generated method stub

//按Entry里面的value降序排序

return o2.getValue().compareTo(o1.getValue());

//按Entry里面的value升序排序

//return o1.getValue().compareTo(o2.getValue());

}

});

/**

*将按value排好序的Entry放入map中

**/

map = null;

map = new LinkedHashMap<Integer, Double>();

for(Map.Entry<Integer, Double> temp:list){

map.put(temp.getKey(), temp.getValue());

}

System.out.println(map.entrySet());

}

}