HashMap与TreeMap按照key和value排序

 package com.sort;

 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;
 import java.util.TreeMap;

 /**
  * Map的排序
  *
  * @author root
  *
  */
 public class MapSort {
     /**
      * TreeMap按照key进行排序
      */
     public static void TreeMapSortByKey() {
         Map<String, String> map = new TreeMap<String, String>(new Comparator<String>() {
             @Override
             public int compare(String o1, String o2) {
                 // 降序排列
                 return o2.compareTo(o1);
             }
         });
         map.put("c", "ccccc");
         map.put("a", "aaaaa");
         map.put("b", "bbbbb");
         map.put("d", "ddddd");
         for (String key : map.keySet()) {
             System.err.println("key:" + key + "  value:" + map.get(key));
         }
     }

     /**
      * TreeMap按照value排序
      */
     public static void TreeMapSortByValue() {
         Map<String, String> map = new TreeMap<String, String>();
         map.put("d", "ccccc");
         map.put("b", "bbbbb");
         map.put("a", "eeeee");
         map.put("c", "ddddd");
         // 将map.entrySet()转换成list
         List<Map.Entry<String, String>> list = new ArrayList<Map.Entry<String, String>>(map.entrySet());
         // 通过比较器来实现排序
         Collections.sort(list, new Comparator<Map.Entry<String, String>>() {
             @Override
             public int compare(Entry<String, String> o1, Entry<String, String> o2) {
                 // 升序排序
                 return o1.getValue().compareTo(o2.getValue());
             }
         });
         for (Map.Entry<String, String> mapping : list) {
             System.out.println(mapping.getKey() + ":" + mapping.getValue());
         }
     }

     /**
      * Map按照Key排序
      */
     public static void MapSortByKey() {
         Map<String, String> map = new HashMap<String, String>();
         map.put("d", "ccccc");
         map.put("b", "bbbbb");
         map.put("a", "eeeee");
         map.put("c", "ddddd");
         // 将map.entrySet()转换成list
         List<Map.Entry<String, String>> list = new ArrayList<Map.Entry<String, String>>(map.entrySet());
         // 通过比较器来实现排序
         Collections.sort(list, new Comparator<Map.Entry<String, String>>() {
             @Override
             public int compare(Map.Entry<String, String> o1, Map.Entry<String, String> o2) {
                 // 升序排序
                 return o1.getKey().compareTo(o2.getKey());
             }
         });
         for (Map.Entry<String, String> mapping : list) {
             System.out.println(mapping.getKey() + ":" + mapping.getValue());
         }
     }

     /**
      * Map按照Value排序
      */
     public static void MapSortByValue() {
         Map<String, String> map = new HashMap<String, String>();
         map.put("d", "ccccc");
         map.put("b", "bbbbb");
         map.put("a", "eeeee");
         map.put("c", "ddddd");
         // 将map.entrySet()转换成list
         List<Map.Entry<String, String>> list = new ArrayList<Map.Entry<String, String>>(map.entrySet());
         // 通过比较器来实现排序
         Collections.sort(list, new Comparator<Map.Entry<String, String>>() {
             @Override
             public int compare(Map.Entry<String, String> o1, Map.Entry<String, String> o2) {
                 // 降序排序
                 return o2.getValue().compareTo(o1.getValue());
             }
         });
         for (Map.Entry<String, String> mapping : list) {
             System.out.println("key:"+mapping.getKey() + "  value:" + mapping.getValue());
         }
     }

     public static void main(String[] args) {
         // MapSort.TreeMapSortByKey();
         // MapSort.TreeMapSortByValue();
         MapSort.MapSortByKey();
         MapSort.MapSortByValue();
     }
 }