map按照key，value比较

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

public class AccordingToKeyOrValueComparison {
	public static void main(String[] args) {
		Map<String, String> map = new HashMap<>();

		map.put("1", "4");
		map.put("3", "3");
		map.put("2", "2");
		map.put("4", "1");

		// Map<String, String> resultMap = sortMapByKey(map);
		// //按Key进行排序：1.treemap的性质
		Map<String, String> resultMap = sortMapByKey2(map); // 按key进行排序：2.list，自定义比较器（排序后需要LinkedHashMap保存）
		// Map<String, String> resultMap = sortMapByValue(map);
		// //按Value进行排序：list，自定义比较器

		for (Map.Entry<String, String> entry : resultMap.entrySet()) {
			System.out.println(entry.getKey() + " " + entry.getValue());
		}
	}

	/**
	 * 使用 TreeMap的性质按key进行排序
	 * 
	 * @param map
	 * @return
	 */
	public static Map<String, String> sortMapByKey(Map<String, String> map) {
		if (map == null || map.isEmpty()) {
			return null;
		}
		// TreeMap默认用key的自然排序，所以不用声明比较器也可以实现key排序，比较器可以自定义排序规则，比如倒序
		// Map<String, String> sortMap = new TreeMap<String, String>();

		// TreeMap构造方法可以有比较器参数~但是比较器只能是对key进行比较
		Map<String, String> sortMap = new TreeMap<String, String>(new MapKeyComparator());

		sortMap.putAll(map);

		return sortMap;
	}

	/**
	 * 使用 list按key进行排序
	 * 
	 * @param map
	 * @return
	 */
	public static Map<String, String> sortMapByKey2(Map<String, String> map) {
		if (map == null || map.isEmpty()) {
			return null;
		}
		List<Map.Entry<String, String>> list = new ArrayList<>(map.entrySet());
		Collections.sort(list, new MapKeyComparator2());

		Map<String, String> sortMap = new LinkedHashMap<>();
		Iterator<Map.Entry<String, String>> iterable = list.iterator();
		while (iterable.hasNext()) {
			Map.Entry<String, String> tmpEntry = iterable.next();
			sortMap.put(tmpEntry.getKey(), tmpEntry.getValue());
		}

		return sortMap;
	}

	/**
	 * 使用 List对Map按value进行排序
	 * 
	 * @param oriMap
	 * @return
	 */
	public static Map<String, String> sortMapByValue(Map<String, String> oriMap) {
		if (oriMap == null || oriMap.isEmpty()) {
			return null;
		}
		// 一定是LinkedHashMap，因为LinkedHashMap保证put顺序和输出顺序一致！
		Map<String, String> sortedMap = new LinkedHashMap<>();

		// map.entry把map的<key,value>当节点装进list，对list排序
		List<Map.Entry<String, String>> entryList = new ArrayList<>(oriMap.entrySet());

		Collections.sort(entryList, new MapValueComparator());

		Iterator<Map.Entry<String, String>> iter = entryList.iterator();
		Map.Entry<String, String> tmpEntry = null;
		while (iter.hasNext()) {
			tmpEntry = iter.next();
			sortedMap.put(tmpEntry.getKey(), tmpEntry.getValue());
		}
		return sortedMap;
	}

}

class MapKeyComparator implements Comparator<String> {

	@Override
	public int compare(String str1, String str2) {

		return str2.compareTo(str1);
	}
}

class MapValueComparator implements Comparator<Map.Entry<String, String>> {

	@Override
	public int compare(Map.Entry<String, String> me1, Map.Entry<String, String> me2) {

		return me1.getValue().compareTo(me2.getValue());
	}
}

class MapKeyComparator2 implements Comparator<Map.Entry<String, String>> {

	@Override
	public int compare(Map.Entry<String, String> me1, Map.Entry<String, String> me2) {

		return me1.getKey().compareTo(me2.getKey());
	}

}

转载：http://blog.51cto.com/13580976/2147994