1 package fanxing;
3 import java.util.ArrayList;
4 import java.util.HashMap;
5 import java.util.Iterator;
6 import java.util.LinkedHashMap;
7 import java.util.List;
8 import java.util.Map;
9 import java.util.Set;
10
11 import org.junit.Test;
12
13 public class demo {
14
15 @Test
16 public void test()
17 {
18 List<String> list=new ArrayList<String>();
19 list.add("aa");
20 list.add("bb");
21 list.add("cc");
22 //传统方式
23 Iterator<String> it=list.iterator();
24 while(it.hasNext())
25 {
26 String a=it.next();
27 System.out.println(a);
28 }
29 //增强for方式
30 for(String s:list)
31 {
32 System.out.println(s);
33 }
34 }
35 @Test
36 public void test1()
37 {
38 Map<Integer, String> map=new LinkedHashMap<Integer, String>(); //必须是Integer,不能使int
39 map.put(12, "aa");
40 map.put(13, "bb");
41 map.put(14, "cc");
42 //传统方式 keyset entryset(重要)
43 Set<Map.Entry<Integer, String>> set=map.entrySet();
44 Iterator<Map.Entry<Integer, String>> it=set.iterator();
45 while(it.hasNext())
46 {
47 Map.Entry<Integer, String> entry=it.next();
48 int key=entry.getKey();
49 String value=entry.getValue();
50 System.out.println(key+"="+value);
51 }
52 //增强for
53 for(Map.Entry<Integer, String>entry:map.entrySet())
54 {
55 int key=entry.getKey();
56 String value=entry.getValue();
57 System.out.println(key+"="+value);
58 }
59
60 }
61 }
