创建型---单实例 Singleton

 1 package com.design;
 2 
 3 /**
 4  * 测试类
 5  * @author Administrator
 6  *
 7  */
 8 public class Test {
 9     /**
10      * 主函数
11      * @param args
12      */
13     public static void main(String[] args) {
14         Singleton first_inst = Singleton.getInstance();
15         first_inst.setString("8288282");
16         
17         Singleton sencond_inst = Singleton.getInstance();
18         System.out.println("sencond_inst : " + sencond_inst.getString());
19         sencond_inst.setString("我是单实例");
20         
21         Singleton third_inst = Singleton.getInstance();
22         System.out.println("third_inst : " + third_inst.getString());
23     }
24 }
25 
26 /**
27  * 单实例
28  * @author Administrator
29  *
30  */
31 class Singleton
32 {
33     /**
34      * 获取实例
35      * @return
36      */
37     public static Singleton getInstance()
38     {
39         return myInst;
40     }
41     
42     /**
43      * 获取string
44      * @return
45      */
46     public String getString()
47     {
48         return str;
49     }
50     
51     /**
52      * 设置string
53      * @param str
54      */
55     public void setString(String str)
56     {
57         this.str = str;
58     }
59     
60     /**
61      * 创建实例
62      */
63     private static Singleton myInst = new Singleton();
64     
65     /**
66      * 测试代码
67      */
68     private String str;
69     
70     /**
71      * 私有化构造函数
72      */
73     private Singleton()
74     {
75         str = "";
76     }
77 }