对Map的key和value进行排序

package map;

import java.util.Comparator;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.Set;

import java.util.TreeMap;

public class SortMapKey {

    public static void main(String[] args) {

       Map<String,String> map = new TreeMap<String,String>(new Comparator<String>() {

           public int compare(String key1, String key2) {

              return key2.compareTo(key1);

              }

       });

       //map.put(null, null);

       map.put("aa", null);

       map.put("bb", "123");

       map.put("dd", "456");

       map.put("cc", "789");

       Set<String> keySet = map.keySet();

       for (String key : keySet) {

           System.out.println(key + ":" + map.get(key));

       }

    }

}

package map;

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Comparator;

import java.util.Date;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

import java.util.TreeMap;

publicclass SorMaptValue {

    publicstaticvoid main(String[] args) {

       Map<String,Date> hashMap = new HashMap<String, Date>();

       Calendar calendar = Calendar.getInstance();

       calendar.add(Calendar.DATE, -1);

       hashMap.put("昨天", calendar.getTime());

       calendar.add(Calendar.DATE, 1);

       hashMap.put("今天", calendar.getTime());

       calendar.add(Calendar.DATE, 1);

       hashMap.put("明天", calendar.getTime());

       SortValueComparator svc = new SortValueComparator(hashMap);

       Map<String,Date> map = new TreeMap<String, Date>(svc);

       map.putAll(hashMap);

       Set<String> keySet = map.keySet();

       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

       for (String key : keySet) {

           System.out.println(key + ":" + sdf.format(hashMap.get(key)));

       }

    }

}

class SortValueComparator implements Comparator<String>{

    private Map<String,Date> map ;

    public SortValueComparator(Map<String,Date> map) {

       this.map = map;

    }

    publicint compare(String o1, String o2) {

       boolean flag = map.get(o1).before(map.get(o2));

       if(flag){

           return 1;

       }else{

           return -1;

       }

    }

}