ErrorEventArgs クラス

定義

名前空間:

System.IO

アセンブリ:

System.IO.FileSystem.Watcher.dll

ソース:

ErrorEventArgs.cs

Error イベントのデータを提供します。

public ref class ErrorEventArgs : EventArgs

public class ErrorEventArgs : EventArgs

type ErrorEventArgs = class
    inherit EventArgs

Public Class ErrorEventArgs
Inherits EventArgs

継承

Object

EventArgs

ErrorEventArgs

例

次の例では、 の ErrorEventArgs 新しいインスタンスを作成し、 を Exception使用して初期化します。 次に、 を呼び出 GetException して を Exception 取得し、エラー メッセージを表示します。 このコードに関連付けられているフォームはありません。

int main()
{
   
   // Creates an exception with an error message.
   Exception^ myException = gcnew Exception( "This is an exception test" );
   
   // Creates an ErrorEventArgs with the exception.
   ErrorEventArgs^ myErrorEventArgs = gcnew ErrorEventArgs( myException );
   
   // Extracts the exception from the ErrorEventArgs and display it.
   Exception^ myReturnedException = myErrorEventArgs->GetException();
   MessageBox::Show( String::Concat( "The returned exception is: ", myReturnedException->Message ) );
}

public static void Main(string[] args) {
    // Creates an exception with an error message.
    Exception myException= new Exception("This is an exception test");

    // Creates an ErrorEventArgs with the exception.
    ErrorEventArgs myErrorEventArgs = new ErrorEventArgs(myException);

    // Extracts the exception from the ErrorEventArgs and display it.
    Exception myReturnedException = myErrorEventArgs.GetException();
    MessageBox.Show("The returned exception is: " + myReturnedException.Message);
 }

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

次の例では、FileSystemWatcher を作成して、ディスク ドライブで発生するファイルの変更 (作成、削除、名前変更、変更) を監視する方法を示します。 この例では、エラー通知を適切に受信する方法も示しています。

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        //  Create a FileSystemWatcher to monitor all files on drive C.
        FileSystemWatcher fsw = new FileSystemWatcher("C:\\");

        //  Watch for changes in LastAccess and LastWrite times, and
        //  the renaming of files or directories.
        fsw.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
            | NotifyFilters.FileName |NotifyFilters.DirectoryName;

        //  Register a handler that gets called when a
        //  file is created, changed, or deleted.
        fsw.Changed += new FileSystemEventHandler(OnChanged);

        fsw.Created += new FileSystemEventHandler(OnChanged);

        fsw.Deleted += new FileSystemEventHandler(OnChanged);

        //  Register a handler that gets called when a file is renamed.
        fsw.Renamed += new RenamedEventHandler(OnRenamed);

        //  Register a handler that gets called if the
        //  FileSystemWatcher needs to report an error.
        fsw.Error += new ErrorEventHandler(OnError);

        //  Begin watching.
        fsw.EnableRaisingEvents = true;

        Console.WriteLine("Press \'Enter\' to quit the sample.");
        Console.ReadLine();
    }

    //  This method is called when a file is created, changed, or deleted.
    private static void OnChanged(object source, FileSystemEventArgs e)
    {
        //  Show that a file has been created, changed, or deleted.
        WatcherChangeTypes wct = e.ChangeType;
        Console.WriteLine("File {0} {1}", e.FullPath, wct.ToString());
    }

    //  This method is called when a file is renamed.
    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        //  Show that a file has been renamed.
        WatcherChangeTypes wct = e.ChangeType;
        Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, wct.ToString());
    }

    //  This method is called when the FileSystemWatcher detects an error.
    private static void OnError(object source, ErrorEventArgs e)
    {
        //  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 (e.GetException().GetType() == typeof(InternalBufferOverflowException))
        {
            //  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));
        }
    }
}

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

注釈

ErrorEventArgs には、イベントの Exception 原因となった が FileSystemWatcher.Error 含まれています。 このクラスは、例外を GetException 取得するメソッドを提供します。

コンストラクター

ErrorEventArgs(Exception)

ErrorEventArgs クラスの新しいインスタンスを初期化します。

メソッド

Equals(Object)	指定されたオブジェクトが現在のオブジェクトと等しいかどうかを判断します。 (継承元 Object)
GetException()	発生したエラーを表す Exception を取得します。
GetHashCode()	既定のハッシュ関数として機能します。 (継承元 Object)
GetType()	現在のインスタンスの Type を取得します。 (継承元 Object)
MemberwiseClone()	現在の Object の簡易コピーを作成します。 (継承元 Object)
ToString()	現在のオブジェクトを表す文字列を返します。 (継承元 Object)

こちらもご覧ください

• ErrorEventHandler
• FileSystemWatcher
• OnError(ErrorEventArgs)