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ErrorEventArgs Class

Provides data for the Error event.

Namespace:  System.IO
Assembly:  System (in System.dll)

'Declaration
Public Class ErrorEventArgs _
	Inherits EventArgs
'Usage
Dim instance As ErrorEventArgs

ErrorEventArgs contains the Exception that caused the Error event. This class provides the GetException method to retrieve the exception.

The following example creates a new instance of ErrorEventArgs and initializes it with an Exception. Then the example calls GetException to retrieve the Exception and display the error message. There is no form associated with this code.

Overloads Public Shared Sub Main(args() As String)
    ' Creates an exception with an error message. 
    Dim myException As New Exception("This is an exception test")

    ' Creates an ErrorEventArgs with the exception. 
    Dim myErrorEventArgs As New ErrorEventArgs(myException)

    ' Extracts the exception from the ErrorEventArgs and display it. 
    Dim myReturnedException As Exception = myErrorEventArgs.GetException()
    MessageBox.Show(("The returned exception is: " & myReturnedException.Message))
End Sub 'Main

The following example shows how to create a FileSystemWatcher to monitor file changes (creates, deletes, renames, changes) occurring on a disk drive. The example also shows how to properly receive error notifications.

Imports System.IO

Module Module1
    Sub Main()
        ' Create a FileSystemWatcher to monitor all files on drive C. 
        Dim fsw As New FileSystemWatcher("C:\")

        ' Watch for changes in LastAccess and LastWrite times, and 
        ' the renaming of files or directories. 
        fsw.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite _ 
            Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)

        ' Register a handler that gets called when a  
        ' file is created, changed, or deleted. 
        AddHandler fsw.Changed, New FileSystemEventHandler(AddressOf OnChanged)

        ' The commented line of code below is a shorthand of the above line. 
        ' AddHandler fsw.Changed, AddressOf OnChanged 

        ' NOTE: The shorthand version is used in the remainder of this code. 
        ' FileSystemEventHandler 
        AddHandler fsw.Created, AddressOf OnChanged 
        ' FileSystemEventHandler 
        AddHandler fsw.Deleted, AddressOf OnChanged

        ' Register a handler that gets called when a file is renamed. 
        ' RenamedEventHandler 
        AddHandler fsw.Renamed, AddressOf OnRenamed

        ' Register a handler that gets called if the  
        ' FileSystemWatcher needs to report an error. 
        ' ErrorEventHandler 
        AddHandler fsw.Error, AddressOf OnError

        ' Begin watching.
        fsw.EnableRaisingEvents = True 

        ' Wait for the user to quit the program.
        Console.WriteLine("Press 'Enter' to quit the sample.")
        Console.ReadLine()
    End Sub 

    ' This method is called when a file is created, changed, or deleted. 
    Private Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs)

        ' Show that a file has been created, changed, or deleted. 
        Dim wct As WatcherChangeTypes = e.ChangeType
        Console.WriteLine("File {0} {1}", e.FullPath, wct.ToString())
    End Sub 

    ' This method is called when a file is renamed. 
    Private Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs)

        ' Show that a file has been renamed. 
        Dim wct As WatcherChangeTypes = e.ChangeType
        Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, wct.ToString())
    End Sub 

    ' This method is called when the FileSystemWatcher detects an error. 
    Private Sub OnError(ByVal source As Object, ByVal e As ErrorEventArgs)

        ' Show that an error has been detected.
        Console.WriteLine("The FileSystemWatcher has detected an error")

        ' Give more information if the error is due to an internal buffer overflow. 
        If TypeOf e.GetException Is InternalBufferOverflowException Then 
            ' This can happen if Windows is reporting many file system events quickly  
            ' and internal buffer of the  FileSystemWatcher is not large enough to handle this 
            ' rate of events. The InternalBufferOverflowException error informs the application 
            ' that some of the file system events are being lost.
            Console.WriteLine( _
                "The file system watcher experienced an internal buffer overflow: " _
                + e.GetException.Message)
        End If 
    End Sub 
End Module

System.Object
  System.EventArgs
    System.IO.ErrorEventArgs

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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