推荐 使用Iterator遍历

Map<Integer, Integer> map = new HashMap<Integer, Integer>();
Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator();
while (entries.hasNext()) {
  Map.Entry<Integer, Integer> entry = entries.next();
  System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue()); 
}