LinkedHashMap 排序

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

public  class  TestMapSortByValue {

    public  static  void  main(String[] args) {
        Map map =  new  HashMap();
        map.put( "d" , 4 );
        map.put( "a" , 1 );
        map.put( "c" , 3 );
        map.put( "e" , 5 );
        map.put( "b" , 2 );
        //排序前
        System.out.println( "before sort" );
        for (Map.Entry entry:map.entrySet()){
            System.out.println(entry.getKey()+ "->" +entry.getValue());
        }
        System.out.println();

        //将map转成list
        List> infos =  new  ArrayList>(map.entrySet());
        //对list排序,实现新的比较器
        Collections.sort(infos,  new  Comparator>(){
            @Override
            public  int  compare(Map.Entry o1, Map.Entry o2) {
                return  o1.getValue() - o2.getValue();
            }
        });
        //申明新的有序 map,根据放入的数序排序
        Map lhm =  new  LinkedHashMap();
        //遍历比较过后的map,将结果放到LinkedHashMap
        for (Map.Entry entry:infos){
            lhm.put(entry.getKey(), entry.getValue());
        }
        //遍历LinkedHashMap,打印值
        System.out.println( "after sort" );
        for (Map.Entry entry:lhm.entrySet()){
            System.out.println(entry.getKey()+ "->" +entry.getValue());
        }
    }
}

before sort
d->4
e->5
b->2
c->3
a->1

after sort
a->1
b->2
c->3
d->4
e->5