1 public static void main(String[] args) {
 2         List<Object> list = new ArrayList<Object>();
 3         list.add("a");
 4         list.add("b");
 5         list.add("c");
 6         Aggregate aggregate = new ConcreteAggregate(list);
 7         Iterator iterator = aggregate.iterator();
 8 
 9         while (iterator.hasNext()) {
10             String o = (String) iterator.next();
11             System.out.println(o);
12         }
13     }
14 
15 }
16 
17 interface Iterator {
18 
19     public Object next();
20 
21     public boolean hasNext();
22 
23 }
24 
25 class ConcreteIterator implements Iterator {
26     private List<Object> list;
27     private int cursor = 0;// 当前游标位置
28 
29     public ConcreteIterator(List<Object> list) {
30         this.list = list;
31 
32     }
33 
34     public boolean hasNext() {
35         // TODO Auto-generated method stub
36         return !(cursor == list.size());
37     }
38 
39     public Object next() {
40         // TODO Auto-generated method stub
41         Object obj = null;
42         if (hasNext()) {
43             obj = list.get(cursor++);
44         }
45         return obj;
46     }
47 }
48 
49 // 模拟集合接口 增删 差(遍历)
50 interface Aggregate {
51 
52     public void add(Object obj);
53 
54     public void remove(Object obj);
55 
56     public Iterator iterator();
57 
58 }
59 
60 class ConcreteAggregate implements Aggregate {
61     private List<Object> list;
62 
63     public ConcreteAggregate(List<Object> list) {
64         this.list = list;
65 
66     }
67 
68     public void add(Object obj) {
69         list.add(obj);
70 
71     }
72 
73     public Iterator iterator() {
74         // TODO Auto-generated method stub
75         return new ConcreteIterator(list);
76     }
77 
78     public void remove(Object obj) {
79         list.remove(obj);
80 
81     }
82 
83 }