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


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


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