HashMap与TreeMap按照key和value排序

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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();    }}
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