Map集合的四种遍历

 1 　　@Test
 2     public void demo() {
 3         Map<String, String> map=new HashMap<String, String>();
 4         map.put("aa", "王琦");
 5         map.put("bb", "张三");
 6         map.put("cc", "李四");
 7         map.put("dd", "王五");
 8         
 9         Set<String> set = map.keySet();
10         for (String string : set) {
11             System.out.println(string);
12         }
13         
14         System.out.println("----------------------------------");
15         
16         Collection<String> values = map.values();
17         for (String string : values) {
18             System.out.println(string);
19         }
20         
21         System.out.println("----------------------------------");
22         
23         Set<String> set2 = map.keySet();
24         for (String string : set2) {
25             System.out.println(string+"-----"+map.get(string));
26         }
27         
28         System.out.println("==============================");
29         
30         Set<Entry<String, String>> entrySet = map.entrySet();
31         for (Entry<String, String> entry : entrySet) {
32             System.out.println(entry);
33         }
34         
35     }