Java Map 按Key排序和按Value排序【转】【补】

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());
}
}
}