用KeySet()方法；

Map
     
       map = new HashMap
      
       ();        map.put(01, "a");        map.put(02, "b");        map.put(03, "c");        map.put(04, "d");        Set set = map.keySet();        ArrayList
       
         list = new  ArrayList
        
         (set);        for (int i = 0; i < list.size(); i++) {            int s = list.get(i);            System.out.println(s);            Object o = map.get(s);            System.out.println(o);            System.out.println("==");