1 HashMap<String, String> map = new HashMap<>();
2 //第一种：普遍使用，二次取值
3 System.out.println("通过Map.keySet遍历key和value：");
4 for (String key : map.keySet()) {
5 System.out.println("key= " + key + " and value= " + map.get(key));
6 }
7
8 //第二种
9 System.out.println("通过Map.entrySet使用iterator遍历key和value：");
10 Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
11 while (it.hasNext()) {
12 Map.Entry<String, String> entry = it.next();
13 System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
14 }
15
16 //第三种：推荐，尤其是容量大时
17 System.out.println("通过Map.entrySet遍历key和value");
18 for (Map.Entry<String, String> entry : map.entrySet()) {
19 System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
20 }
21
22 //第四种
23 System.out.println("通过Map.values()遍历所有的value，但不能遍历key");
24 for (String v : map.values()) {
25 System.out.println("value= " + v);
26 }
27 }
