根据数值取键

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class TestMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Map m1 = new HashMap();
		Map m2 = new HashMap();
		
		m1.put("a", new Integer(1));
		m1.put("b", new Integer(2));
		m1.put("b", "3");
		
		m2.put("f", new Integer(1));
		m2.put("x", new Integer(2));
		m2.put("y", new Integer(2));
		m2.put("z", new Integer(2));
		
		m2.put("w", new String("abcd"));
		
		//System.out.println(m2.containsKey("q"));
		//System.out.println(m2.containsValue(new Integer(2)));
		if(m2.containsValue(new Integer(2))){
			Set<Map.Entry<Object,Object>> s = m2.entrySet();
			Iterator i = s.iterator();
			while(i.hasNext()){
				Map.Entry<Object,Object> m = (Map.Entry<Object,Object>)i.next();
				if(m.getValue().equals(new Integer(2))){
					System.out.print(m.getKey() + " ");
				}
				
			}
			//System.out.println(m2.entrySet());
		}
		else{
			System.out.println("查无此项");
		}
		
		
	}

}