将Map中的值拷贝到另一个Map中

public static void main(String[] args) {  
    //造数  
    Map<String,Object> paramMap=new HashMap<String,Object>();  
    paramMap.put("name", "name");  
    paramMap.put("nick", "nick");  
    paramMap.put("pass", "pass");  
    paramMap.put("tel", "tel");  
    paramMap.put("email", "email");  
          
    Map<String,Object> resultMap=new HashMap<String,Object>();  
          
    //开始从paramMap中复制到resultMap中  
    Iterator it=paramMap.entrySet().iterator();  
    while(it.hasNext()) {  
        Map.Entry entry=(Map.Entry)it.next();  
        Object key=entry.getKey();  
        if(key!=null && paramMap.get(key)!=null) {  
            resultMap.put(key.toString(), paramMap.get(key));  
        }  
    }  
    //执行结束  
    System.out.println(resultMap.size());  
}