Java Map按照Key和Value排序【转】

 Java中Map按照Key和Value排序

package kingtool.sort;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.Map.Entry;
/**
 * 
 * @author King
 *
 */
public class MapSortTool {
    public static void main(String[] args) {

        Map<String, String> map = new TreeMap<String, String>();
        map.put("4", "2");
        map.put("1", "1");
        map.put("9", "3");
        map.put("8", "6");

//      Map<String, String> resultMap = sortMapByKey(map); //按Key进行排序
        Map<String, String> resultMap = sortMapByValue(map); // 按Value进行排序

        for (Map.Entry<String, String> entry : resultMap.entrySet()) {
            System.out.println(entry.getKey() + " " + entry.getValue());
        }
    }
    /**
     * 使用 Map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;
        }
        Map<String, String> sortMap = new TreeMap<String, String>(new MapKeyStringComparator());
        sortMap.putAll(map);
        return sortMap;
    }

    /**
     * 使用 Map按value进行排序
     * 
     * @param map
     * @return
     */
    public static Map<String, String> sortMapByValue(Map<String, String> oriMap) {
        if (oriMap == null || oriMap.isEmpty()) {
            return null;
        }
        Map<String, String> sortedMap = new LinkedHashMap<String, String>();
        List<Map.Entry<String, String>> entryList = new ArrayList<Map.Entry<String, String>>(oriMap.entrySet());
        Collections.sort(entryList, new MapValueStringComparator());

        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;
    }

    /**
     * string key升序
     * @author King
     *
     */
    static class MapKeyStringComparator implements Comparator<String>{

        @Override
        public int compare(String str1, String str2) {
            return str1.compareTo(str2);
        }
    }
    
    /**
     * string value升序
     * @author King
     *
     */
    static class MapValueStringComparator implements Comparator<Map.Entry<String, String>> {

        @Override
        public int compare(Entry<String, String> entry1, Entry<String, String> entry2) {
            return entry1.getValue().compareTo(entry2.getValue());
        }
    }
    
    
    /**
     * tip: 样例中没用到<br/>
     * double value降序
     * @author King
     *
     */
    static class MapValueNumberComparator implements Comparator<Map.Entry<String, Double>> {
        @Override
        public int compare(Entry<String, Double> entry1, Entry<String, Double> entry2) {
            return entry1.getValue().compareTo(entry2.getValue());
        }
    }
}