1 import java.util.ArrayList;
2 import java.util.Iterator;
3 import java.util.List;
4
5 /**
6 *遍历集合List
7 * @author Men、叔
8 * Email 844357411@qq.com 【Men 叔 Java厂】：http://jq.qq.com/?_wv=1027&k=cfqLhZ
9 */
10 public class Demo {
11
12 /**
13 * @param args
14 */
15 public static void main(String[] args) {
16
17 List list = new ArrayList();
18 list.add("aaa");
19 list.add("bbb");
20 //1:利用下标
21 for(int i = 0 ; i< list.size();i++){
22
23 System.out.println(list.get(i));
24 }
25 //2:for- each
26 for(Object o:list){
27 System.out.println(o);
28 }
29 //3:迭代器
30 Iterator it = list.iterator();
31 while(it.hasNext()){
32 System.out.println(it.next());
33 }
34 //4:Object数组
35 Object o[];
36 o = list.toArray();
37 for(int i = 0 ; i <o.length;i++){
38 System.out.println(o[i]);
39 }
40 //5:toString
41 System.out.println(list.toString());
42
43 }
44
45 }
46 public class Demo{
47 public static void main(String[] args) {
48
49
50 Map<String, String> map = new HashMap<String, String>();
51 map.put("1", "value1");
52 map.put("2", "value2");54
55 //1：普遍使用，二次取值
56 System.out.println("通过Map.keySet遍历key和value：");
57 for (String key : map.keySet()) {
58 System.out.println("key= "+ key + " and value= " + map.get(key));
59 }
60
61 //2:迭代器遍历
62 System.out.println("通过Map.entrySet使用iterator遍历key和value：");
63 Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
64 while (it.hasNext()) {
65 Map.Entry<String, String> entry = it.next();
66 System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
67 }
68
69 //3：foreach 推荐，尤其是容量大时
70 System.out.println("通过Map.entrySet遍历key和value");
71 for (Map.Entry<String, String> entry : map.entrySet()) {
72 System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
73 }
74
75 //4
76 System.out.println("通过Map.values()遍历所有的value，但不能遍历key");
77 for (String v : map.values()) {
78 System.out.println("value= " + v);
79 }
80 }
81 }
