Map排序(按key/按value)

package com.abc.test;
 
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.Map.Entry;
 
/**
 * 可能会遇到这样的情况，我可能要对Map<key,value>的集合进行排序，而这种排序又分为两种情况，你可能按key值排序；
 * 另外你也可能会遇到按value值进行排序的情况。
 * 大家都知道，默认的情况下，TreeMap：是按key升序,进行排序的；LinkedHashMap：是按加入顺序进行排序的
 * ；HashMap：内部数值的顺序并不是以存放的先后顺序为主
 * ，而是以hash值的顺序为主，其次才是存放的先后顺序。在这里我们只讨论如何实现HashMap的排序。
 *
 */
@SuppressWarnings("unchecked")
public class MapSortTest {
 
	public static void main(String[] args) {
		//初始化map
		Map<String, Integer> map=getMapInstance();
		printMap(map);
 
		//选择操作
		Scanner input=new Scanner(System.in);
		int num=input.nextInt();
		switch (num) {
			case 0:
				System.exit(0);
				break;
			case 1:
				Map<String, Integer> sortMaps = sortMapByKey(map);
				printMap(sortMaps);
				break;
			case 2:
				sortMapByValue(map);
				break;
			case 3:
				mapSortByKey(map);
				break;
			case 4:
				mapSortByValue(map);
				break;
			default:
				System.out.println("error input!");
				break;
		}
 
	}
 
	public static Map sortMapByKey(Map map) {
		Map<Object, Object> mapVK = new TreeMap<Object, Object>(
				new Comparator<Object>() {
					public int compare(Object obj1, Object obj2) {
						String v1 = (String) obj1;
						String v2 = (String) obj2;
						int s = v2.compareTo(v1);
						return s;
					}
				});
		Set col = map.keySet();
		Iterator iter = col.iterator();
		while (iter.hasNext()) {
			String key = (String) iter.next();
			Integer value = (Integer) map.get(key);
			mapVK.put(key, value);
		}
		return mapVK;
	}
 
	public static void sortMapByValue(Map maps) {
		List<Map.Entry<String, Integer>> info = new ArrayList<Map.Entry<String, Integer>>(maps.entrySet());
		Collections.sort(info, new Comparator<Map.Entry<String, Integer>>() {
			public int compare(Map.Entry<String, Integer> obj1,Map.Entry<String, Integer> obj2) {
				return obj2.getValue() - obj1.getValue();
			}
		});
		for (int j = 0; j < info.size(); j++) {
			System.out.println(info.get(j).getKey() + "------->"+ info.get(j).getValue());
		}
	}
 
	// ====================================================================================
	private static SortedMap<String, Integer> mapSortByKey(Map<String, Integer> unsort_map) {
		TreeMap<String, Integer> result = new TreeMap<String, Integer>();
		Object[] unsort_key = unsort_map.keySet().toArray();
		Arrays.sort(unsort_key);
		for (int i = 0; i < unsort_key.length; i++) {
			result.put(unsort_key[i].toString(), unsort_map.get(unsort_key[i]));
		}
		return result.tailMap(result.firstKey());
	}
 
	public static void mapSortByValue(Map map) {
		List arrayList = new ArrayList(map.entrySet());
		Collections.sort(arrayList,new Comparator(){
			@Override
			public int compare(Object o1, Object o2) {
				Map.Entry obj1 = (Map.Entry)o1;
				Map.Entry obj2 = (Map.Entry)o2;
				return obj1.getValue().toString().compareTo(obj2.getValue().toString());
			}
		});
		for(Iterator it = arrayList.iterator();it.hasNext();){
			Map.Entry entry = (Map.Entry)it.next();
			System.out.println(entry.getKey()+":"+entry.getValue());
		}
	}
	public static void abc(Map map){
		TreeMap treemap = new TreeMap(map);
	}
	public static void abcd() {
		Map<String, Integer> keyfreqs = new HashMap<String, Integer>();
		ArrayList<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>(keyfreqs.entrySet());
		Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
			public int compare(Map.Entry<String, Integer> o1,Map.Entry<String, Integer> o2) {
				return (o2.getValue() - o1.getValue());
			}
		});
		for (Entry<String, Integer> e : list) {
			System.out.println(e.getKey() + "::::" + e.getValue());
		}
	}
	public static Map getMapInstance(){
		Map<String, Integer> map = new HashMap<String, Integer>();
		map.put("apple",40);
		map.put("boy",30);
		map.put("cat",20);
		map.put("dog",10);
		return map;
	}
	public static void printMap(Map map){
		Iterator i = map.entrySet().iterator();
		while (i.hasNext()) {
			Map.Entry<String, Integer> entry = (Map.Entry<String, Integer>) i.next();
			System.out.println(entry.getKey() + ":"+ entry.getValue());
		}
		System.out.println("========================================================");
	}
}