异常(Exception)

1、IOException

 1 public static void Test1()
 2         {
 3             FileStream fs = null;
 4             try
 5             {
 6                 fs = new FileStream("d:\file.txt", FileMode.Open);
 7                 fs.ReadByte();
 8                 Console.WriteLine("OK");
 9             }
10             catch (IOException)
11             {
12                 Console.WriteLine("IOException");
13             }
14             catch
15             {
16                 Console.WriteLine("ELSE Exception");
17             }
18             finally
19             {
20                 if (fs != null)
21                 {
22                     fs.Close();
23                     fs = null;
24                 }
25             }
26         }

IOException

2、FileNotFoundException 继承自 IOException

 1         public static void Test1()
 2         {
 3             FileStream fs = null;
 4             try
 5             {
 6                 fs = new FileStream("d:\file.txt", FileMode.Open);
 7                 fs.ReadByte();
 8                 Console.WriteLine("OK");
 9             }
10             catch (FileNotFoundException)
11             {
12                 Console.WriteLine("FileNotFoundException");
13             }
14             catch (IOException)
15             {
16                 Console.WriteLine("IOException");
17             }
18             finally
19             {
20                 if (fs != null)
21                 {
22                     fs.Close();
23                     fs = null;
24                 }
25             }
26         }

FileNotFoundException

3、NullReferenceException

 1         /// <summary>
 2         /// 委托
 3         /// </summary>
 4         /// <param name="str">委托参数</param>
 5         public delegate void Show(string str);
 6 
 7         /// <summary>
 8         /// 事件
 9         /// </summary>
10         public static event Show ShowEvent;
11 
12         public static void Test2()
13         {
14             try
15             {
16                 Console.WriteLine(ShowEvent.GetInvocationList().Count());
17             }
18             catch (NullReferenceException)
19             {
20                 Console.WriteLine("NullReferenceException");
21             }
22         }

NullReferenceException