两个Map合并 成一个map

public static void main(String args[])
  {
   Map<String, Object>  map =new HashMap<String, Object>();
   Map<String, Object>  map1 =new HashMap<String, Object>();
   
   map.put("1",new Integer(1));
   map.put("2", new Integer(2));
   map1.put("3", new Integer(3));
   map1.put("4", new Integer(4));
   map.putAll(map1);
   System.out.println(map1);
   
   System.out.println(map);
  }

结果是：

{3=3, 4=4}
{3=3, 2=2, 1=1, 4=4}