One way to use a singleton as a global variable

Content of this article: a simple way to use a single instance as a global variable. Use the Code to make it clearer.

Userpool. CS

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 1 class UserPool
 2     {
 3 publicstaticreadonly UserPool GlobalUserPool =new UserPool();
 4 private Hashtable ht =new Hashtable();
 5 
 6 private UserPool()
 7         {
 8         }
 9 publicvoid Add(string key, UserInformation userInfor)
10         {
11 lock (ht.SyncRoot)
12             {
13                 ht[key] = userInfor;
14             }
15         }
16 
17 publicvoid Remove(string key)
18         {
19 if (ht.ContainsKey(key))
20             {
21 lock (ht.SyncRoot)
22                 {
23 if (ht.ContainsKey(key))
24                     {
25                         ht.Remove(key);
26                     }
27                 }
28             }
29         }
30 
31 public UserInformation GetUserInfo(string key)
32         {
33 if (ht.ContainsKey(key))
34             {
35 lock (ht.SyncRoot)
36                 {
37 if (ht.ContainsKey(key))
38                     {
39 return ht[key] as UserInformation;
40                     }
41 else
42                     {
43 returnnull;
44                     }
45                 }
46             }
47 else
48             {
49 returnnull;
50             }
51         }
52 
53 publicbool ContainsKey(string key)
54         {
55 return ht.ContainsKey(key);
56         }
57     }

Userinformation. CS

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1 class UserInformation
2     {
3 publicstring[] UserFriends { get; set; }
4 publicstring KeyGuid { get; set; }
5 publicstring Name { get; set; }
6     }