Map如何获取所有value的值

/** 
 *  
 * Map获取集合所有value值
 * 
 */  
public class MapDemo   
{  
    public static void main(String[] args)  
    {  
        Map<String,Integer> m = new HashMap<String,Integer>();  
          
        m.put("zhangsan", 19);  
        m.put("lisi", 49);
        m.put("wangwu", 19);  
        m.put("lisi",20);
        m.put("hanmeimei", null);         
        System.out.println(m);  
          
        System.out.println(m.values()); 
    }  
}