Iterator mode of Java design pattern

 Category: "java"2013-07-15 10:58 917 people read reviews (0) favorite reports The so-called iterator mode, that is, iterator provides a unified access for different containers. In this paper, we use the container in Java as an example to simulate the principle of iterator.
Reference: Horse soldier java design mode Iterator
1. First define a container collection interface.
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1. Package com.njupt.zhb.learn.iterator;
3. Public interface Collection {
4. void Add (Object o);
5. int size ();
6. Iterator Iterator ();
7. }

2. Define an interface for an iterator iterator
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1. Package com.njupt.zhb.learn.iterator;
3. Public interface Iterator {
4. Object next ();
5. boolean hasnext ();
6. }

3. Define a ArrayList, implement the collection interface, and write an inner class that implements the iterator interface.
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2. Package com.njupt.zhb.learn.iterator;
6. Import com.njupt.zhb.learn.iterator.Collection;
10. Public class ArrayList implements Collection {
12. Object[] objects = new object[10];
14. int index = 0;
16. public Void Add (Object o) {
18. if (index = = objects.length) {
20. object[] newobjects = new Object[objects.length * 2];
22. System.arraycopy (objects, 0, Newobjects, 0, objects.length);
24. objects = newobjects;
26. }
28. Objects[index] = o;
30. Index + +;
32. }
36. public int size () {
38. return index;
40. }
44. Public Iterator Iterator () {
48. return new Arraylistiterator ();
50. }
54. private class Arraylistiterator implements Iterator {
56. private int currentindex = 0;
60. @Override
62. Public Boolean hasnext () {
64. if (currentindex >= index) return false;
66. Else return true;
68. }
72. @Override
74. Public Object Next () {
76. Object o = Objects[currentindex];
78. Currentindex + +;
80. return o;
82. }
86. }
88. }

4. Write the test procedure Testmain
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2. Package com.njupt.zhb.learn.iterator;
4. Import com.njupt.zhb.learn.iterator.ArrayList;
6. Public class Testmain {
8. public static void Main (string[] args) {
10. Collection C = new ArrayList ();
12. For (int i=0; i<; i++) {
14. C.add ("string" +i);
16. }
18. System.out.println (C.size ());
20. Iterator it = C.iterator ();
22. While (It.hasnext ()) {
24. Object o = It.next ();
26. System.out.println (o.tostring () + "");
28. }
30. }
32. }

Operation Result:

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1. 15
2. String 0
3. String 1
4. String 2
5. String 3
6. String 4
7. String 5
8. String 6
9. String 7
10. String 8
11. String 9
12. String 10
13. String 11
14. String 12
15. String 13
16. String 14

As can be seen from the above, design patterns are used everywhere in object-oriented polymorphic。 interface calls a function in a subclass。 Source code Download:
http://download.csdn.net/detail/nuptboyzhb/5755295

Iterator mode of Java design pattern