VB.Net/Development/Exception Yours

A user-defined exception class

Imports System
Public Class MainClass
   Shared Sub Main()
      " catch any NegativeNumberException thrown
      Try
         Throw New NegativeNumberException("Exception occurred")
          
      Catch formatException As FormatException
         Console.WriteLine(formatException.Message)
         " diplay MessageBox if negative number input
      Catch negativeNumberException As _
         NegativeNumberException
         Console.WriteLine(negativeNumberException.Message)
      End Try
   End Sub " Main
End Class
Public Class NegativeNumberException
   Inherits ApplicationException
   Public Sub New()
      MyBase.New("Illegal operation for a negative number")
   End Sub " New
   " constructor for customizing error message
   Public Sub New(ByVal messageValue As String)
      MyBase.New(messageValue)
   End Sub " New
   " constructor for customizing error message and specifying
   " inner exception object
   Public Sub New(ByVal messageValue As String, _
      ByVal inner As Exception)
      MyBase.New(messageValue, inner)
   End Sub
End Class

Define and Use your own Exception Class

Imports System
Public Class MainClass
    Shared Sub Main(ByVal args As String())
             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")
                 " most derived exception type first
             Catch e As System.DivideByZeroException
                 Console.WriteLine( _
                    "DivideByZeroException! Msg: {0}", e.Message)
                 Console.WriteLine("HelpLink: {0}", e.HelpLink)
                 " catch custom exception
             Catch e As MyCustomException
                 Console.WriteLine( _
                    "MyCustomException! Msg: {0}", e.Message)
                 Console.WriteLine("HelpLink: {0}", e.HelpLink)
             Catch " catch any uncaught exceptions
                 Console.WriteLine("Unknown exception caught")
             Finally
                 Console.WriteLine("Close file here.")
             End Try
    End Sub
         " do the division if legal
         Shared Public 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
                 " create a custom exception instance
                 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
End Class
     Public Class MyCustomException
         Inherits System.ApplicationException
         Public Sub New(ByVal message As String)
             " pass the message up to the base class
             MyBase.New(message)
         End Sub "New
     End Class "MyCustomException

Your own Exception Class

Imports System
Imports System.Text
Imports System.Text.RegularExpressions

Public Class MainClass
         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")
             " most derived exception type first
             Catch e As System.DivideByZeroException
                 Console.WriteLine( _
                    "DivideByZeroException! Msg: {0}", e.Message)
                 Console.WriteLine("HelpLink: {0}", e.HelpLink)
             " catch custom exception
             Catch e As MyCustomException
                 Console.WriteLine( _
                    "MyCustomException! Msg: {0}", e.Message)
                 Console.WriteLine("HelpLink: {0}", e.HelpLink)
             Catch " catch any uncaught exceptions
                 Console.WriteLine("Unknown exception caught")
             Finally
                 Console.WriteLine("Close file here.")
             End Try
         End Sub "Main
         Shared Public 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
   
End Class
     Public Class MyCustomException
         Inherits System.ApplicationException
         Public Sub New(ByVal message As String)
             MyBase.New(message)
         End Sub
     End Class

Your own Object Expired Exception

Imports System
Imports System.Collections
Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Try
            Throw New ObjectExpiredException("This object has expired.")
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class
Public Class ObjectExpiredException
    Inherits System.ApplicationException
    " No parameters. Use a default message.
    Public Sub New()
        MyBase.New("This object has expired")
    End Sub
    " Set the message.
    Public Sub New(ByVal new_message As String)
        MyBase.New(new_message)
    End Sub
    " Set the message and inner exception.
    Public Sub New(ByVal new_message As String, ByVal inner_exception As Exception)
        MyBase.New(new_message, inner_exception)
    End Sub
End Class