遍历HashMap的最佳方式

 public static void printMap(Map mp) {
     Iterator it = mp.entrySet().iterator();
     while (it.hasNext()) {
         Map.Entry pair = (Map.Entry)it.next();
         System.out.println(pair.getKey() + " = " + pair.getValue());
         it.remove(); // avoids a ConcurrentModificationException
     }
 }