в 16:40, 26 мая 2010

2010-05-26T16:40:30Z

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2010-05-26T12:53:42Z

1 версия

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==Create Custom Exception class==

<source lang="vbnet">Option Strict On
Imports System
Public Class MyCustomException
Inherits System.ApplicationException
Public Sub New(ByVal message As String)
MyBase.New(message)
End Sub
End Class
Class Tester
Public Shared Function DoDivide(ByVal a As Double, ByVal b As Double) As Double
If b = 0 Then
Dim e As New DivideByZeroException( )
e.HelpLink = "http://www.vbex.ru"
Throw e
End If
If a = 0 Then
Dim e As New _
MyCustomException("Can"t have zero divisor")
e.HelpLink = "http://www.vbex.ru"
Throw e
End If
Return a / b
End Function "DoDivide
Shared Sub Main( )
Try
Console.WriteLine("Open file here")
Dim a As Double = 0
Dim b As Double = 5
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! Msg: {0}", e.Message)
Console.WriteLine("HelpLink: {0}", e.HelpLink)
Catch e As MyCustomException
Console.WriteLine("MyCustomException! Msg: {0}", e.Message)
Console.WriteLine("HelpLink: {0}", e.HelpLink)
Catch
Console.WriteLine("Unknown exception caught")
Finally
Console.WriteLine("Close file here.")
End Try
End Sub
End Class</source>
<pre class=codeResult>Open file here
MyCustomException! Msg: Can"t have zero divisor
HelpLink: http://www.vbex.ru
Close file here.</pre>

==Create your own Exception class by subclassing System.Exception==

<source lang="vbnet">Imports System.Runtime.Serialization
Public Class CustomException
Inherits System.Exception
Public Sub New()
Me.New("An error occurred in the component.", Nothing)
End Sub
Public Sub New(message As String)
Me.New(message, Nothing)
End Sub
Public Sub New(message As String, innerException As Exception)
MyBase.New(message, innerException)
Source = "My_Custom_Component"
End Sub
Protected Sub New(info As SerializationInfo, context As StreamingContext)
MyBase.New(info, context)
End Sub
End Class</source>

==Demonstrating a user-defined exception class==

<source lang="vbnet">Public Class Tester
Public Shared Sub Main

Try
Console.WriteLine(SquareRoot(123.123))
Console.WriteLine(SquareRoot(-123.123))
Catch formatException As FormatException
Console.WriteLine(formatException.Message)
Catch negativeNumberException As _
NegativeNumberException
Console.WriteLine(negativeNumberException.Message)
End Try
End Sub
Public Shared Function SquareRoot(ByVal operand As Double) As Double
If operand < 0 Then
Throw New NegativeNumberException( _
"Square root of negative number not permitted")
End If
Return Math.Sqrt(operand)
End Function " cmdSquareRoot
End Class

Public Class NegativeNumberException
Inherits ApplicationException
Public Sub New()
MyBase.New("Illegal operation for a negative number")
End Sub " New
Public Sub New(ByVal messageValue As String)
MyBase.New(messageValue)
End Sub " New
Public Sub New(ByVal messageValue As String, _
ByVal inner As Exception)
MyBase.New(messageValue, inner)
End Sub
End Class</source>
<pre class=codeResult>11.0960803890383
Square root of negative number not permitted</pre>

==Inherits System.ApplicationException==

<source lang="vbnet">Imports System.Runtime.Serialization
public class Test
public Shared Sub Main
Try
Throw New MyException("This is my Exception.")
Catch ex As Exception
Console.WriteLine(ex.Message)
End Try
End Sub
End class

Public Class MyException
Inherits System.ApplicationException
Public Sub New()
MyBase.New("This object has expired")
End Sub
Public Sub New(ByVal new_message As String)
MyBase.New(new_message)
End Sub
Public Sub New(ByVal new_message As String, ByVal inner_exception As Exception)
MyBase.New(new_message, inner_exception)
End Sub
Public Sub New(ByVal info As SerializationInfo, _
ByVal context As StreamingContext)
MyBase.New(info, context)
End Sub
End Class</source>
<pre class=codeResult>This is my Exception.</pre>

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VB.Net Tutorial/Development/Custom Exception - История изменений

в 16:40, 26 мая 2010

Admin: 1 версия