1 public static void main(String[] args) {

 2

 3     Map<String, String> map = new HashMap<String, String>();

 4     map.put("1", "value1");

 5     map.put("2", "value2");

 6     map.put("3", "value3");

 7

 8     //第一种：普遍使用，二次取值

 9     System.out.println("通过Map.keySet遍历key和value：");

10     for (String key : map.keySet()) {

11         System.out.println("key= "+ key + " and value= " + map.get(key));

12     }

13

14     //第二种

15     System.out.println("通过Map.entrySet使用iterator遍历key和value：");

16     Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();

17     while (it.hasNext()) {

18         Map.Entry<String, String> entry = it.next();

19         System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());

20     }

21

22     //第三种：推荐，尤其是容量大时

23     System.out.println("通过Map.entrySet遍历key和value");

24     for (Map.Entry<String, String> entry : map.entrySet()) {

25         System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());

26     }

27

28     //第四种

29     System.out.println("通过Map.values()遍历所有的value，但不能遍历key");

30     for (String v : map.values()) {

31         System.out.println("value= " + v);

32     }

33  }