1 package com.shellway.javase;
2 import java.util.ArrayList;
3 import java.util.Collection;
4 import java.util.HashSet;
5 import java.util.Iterator;
6 import java.util.List;
7 import java.util.Map;
8 import java.util.Set;
9 import java.util.TreeMap;
10
11 import org.junit.Test;
12
13 public class TestCollection {
14
15 public static void print(Collection<? extends Object> c){
16 Iterator<? extends Object> it = c.iterator();
17 while (it.hasNext()) {
18 Object object = (Object) it.next();
19 System.out.println(object);
20 }
21 }
22
23 @Test
24 public void demo1(){
25 Set<String> set = new HashSet<String>();
26 set.add("AAA");
27 set.add("BBB");
28 set.add("CCC");
29 print(set);
30
31 //Set的第一种遍历方式:利用Iterator
32 Iterator<String> it1 = set.iterator();
33 for (String ss : set) {
34 System.out.println(ss);
35 }
36 //Set的第一种遍历方式:利用foreach
37 for (String sss : set) {
38 System.out.println(sss);
39 }
40
41
42 List<String> list = new ArrayList<String>();
43 list.add("DDDDD");
44 list.add("EEEEE");
45 list.add("FFFFF");
46 print(list);
47
48 //List的第一种遍历方式:因为list有顺序，利用size()和get()方法获取
49 for (int i = 0; i < list.size(); i++) {
50 System.out.println(list.get(i));
51 }
52 //List的第二种遍历方式：利用Iterator
53 Iterator<String> it = list.iterator();
54 while (it.hasNext()) {
55 System.out.println(it.next());
56 }
57 //List的第三种遍历方式:利用foreach
58 for (String s2 : list) {
59 System.out.println(s2);
60 }
61
62
63 Map<String,String> map = new TreeMap<String, String>();
64 map.put("Jerry", "10000");
65 map.put("shellway", "20000");
66 map.put("Kizi", "30000");
67 print(map.entrySet());
68 //Map的第一种遍历方式：先获得key,再获得值value
69 Set<String> sett = map.keySet();
70 for (String s : sett) {
71 System.out.println(s+":"+map.get(s));
72 }
73 //Map的第二种遍历方式：获得键值对
74 for (Map.Entry<String, String> entry : map.entrySet()) {
75 System.out.println(entry.getKey()+" : "+entry.getValue());
76 }
77 }
78 }
