hashmapsorttest.java

来自「基础性的JAVA源代码」· Java 代码 · 共 95 行

package exec.day1003;
import java.util.*;
public class HashMapSortTest {
	public static void main(String args[]){
		HashMapSortTest t = new HashMapSortTest();
		HashMap map = new HashMap();
		map.put("001", new Integer(6500));
		map.put("002", new Integer(3500));
		map.put("003", new Integer(6500));
		map.put("004", new Integer(2300));
		t.sortHashMap(map);
	}
	/**
	 * 对HashMap排序，按照value降序排列，再按照key升序排列
	 * @param map
	 */
	public void sortHashMap(HashMap map){
		//遍历HashMap，获取每一对key和value，并构建
		//MapSortTest对象，添加到TreeSet中，实现排序
		Set set = map.keySet();
		TreeSet ts = new TreeSet();
		for(Object key:set){
			Object value = map.get(key);
			MapSortTest t = new MapSortTest(key,value);
			ts.add(t);			
		}
		//输出排序后的结果
		for(Object obj:ts){
			System.out.println(obj);
		}
	}
	
	class MapSortTest implements Comparable{
		private Object key;
		private Object value;
		public MapSortTest(Object key,Object value){
			this.key = key;
			this.value = value;
		}
		public String toString(){
			return key+": "+value;
		}
		public int compareTo(Object obj){
			MapSortTest m = (MapSortTest)obj;
			if(key instanceof String && 
					value instanceof Integer){
				int thisValue = ((Integer)this.value).intValue();
				String thisKey = (String)this.key;
				int mValue = ((Integer)m.value).intValue();
				String mKey = (String)m.key;
				if(thisValue==mValue){
					return thisKey.compareTo(mKey);
				}
				return mValue-thisValue;
			}
			if(key instanceof String && 
					value instanceof Double){
				double thisValue = ((Double)this.value).doubleValue();
				String thisKey = (String)this.key;
				double mValue = ((Double)m.value).doubleValue();
				String mKey = (String)m.key;
				if(thisValue==mValue){
					return thisKey.compareTo(mKey);
				}
				if(thisValue>mValue){
					return -1;
				}
				return 1;
			}
			throw new RuntimeException("");
		}
	}
}