VB.Net Tutorial/Development/Finally
Версия от 16:40, 26 мая 2010; (обсуждение)
Содержание
Close Stream in Finally statement
Imports System.IO
public class Test
public Shared Sub Main
Dim srReader As IO.StreamReader
Dim strLine As String
Dim blnDone As Boolean = False
Dim strFileName As String = "test.txt"
"Read text from a file and display it in a list box.
srReader = New IO.StreamReader(strFileName)
Try
While Not blnDone
strLine = srReader.ReadLine()
If strLine Is Nothing Then
blnDone = True
Else
Console.WriteLine(strLine)
End If
End While
srReader.Close()
Catch ex As Exception
Console.WriteLine("An error has occurred.")
Finally
srReader.Close()
End Try
End Sub
End class
Finally after multiple catch statements
Module Module1
Sub Main()
Dim intItem1 As Integer = 0
Dim intItem2 As Integer = 128
Dim intResult As Integer
Try
intResult = intItem2 / intItem1
Catch e As OverflowException
Console.WriteLine("An overflow exception occurred.")
Catch e As OutOfMemoryException
Console.WriteLine("Out of memory.")
Catch e As IndexOutOfRangeException
Console.WriteLine("Array index out of range.")
Finally
Console.WriteLine("Finally")
End Try
End Sub
End Module
An overflow exception occurred. Finally
Finally always executes
Public Class Tester
Public Shared Sub Main
DoesNotThrowException()
End Sub
Public Shared Sub DoesNotThrowException()
Try
Console.WriteLine("In DoesNotThrowException")
Catch
Console.WriteLine("This Catch never executes")
Finally
Console.WriteLine("Finally executed in DoesNotThrowException")
End Try
Console.WriteLine("End of DoesNotThrowException")
End Sub " DoesNotThrowException
End Class
In DoesNotThrowException Finally executed in DoesNotThrowException End of DoesNotThrowException
Try Catch with Finally clause
Option Strict On
Imports System
Class Tester
Public Shared Function DoDivide(ByVal a As Double, ByVal b As Double) As Double
If b = 0 Then
Throw New System.DivideByZeroException( )
End If
If a = 0 Then
Throw New System.ArithmeticException( )
End If
Return a / b
End Function "DoDivide
Shared Sub Main( )
Try
Console.WriteLine("Open file here")
Dim a As Double = 5
Dim b As Double = 0
Console.WriteLine("{0} / {1} = {2}", a, b, DoDivide(a, b))
Console.WriteLine("This line may or may not print")
Catch e As System.DivideByZeroException
Console.WriteLine("DivideByZeroException caught!")
Catch
Console.WriteLine("Unknown exception caught!")
Finally
Console.WriteLine("Close file here.")
End Try
End Sub
End Class
Open file here DivideByZeroException caught! Close file here.