The following code example raises a ThreadException event when button1 on the form is clicked. The example creates two classes. The ErrorHandler class creates the form and button that raises the event. The CustomExceptionHandler class provides the methods to handle the exception.
In Main in the ErrorHandler class, the code creates a new instance of the exception handling class, that is, an instance of the CustomExceptionHandler. Then the instance is added to the event, and the application is run.
In the OnThreadException method in the CustomExceptionHandler class, the example uses a try...catch...finally statement to process the exception. The ShowThreadExceptionDialog method creates the message to display, and displays it in a message box.
' Creates a class to throw the error.
Public Class ErrorHandler
Inherits System.Windows.Forms.Form
' Inserts the code to create a form with a button.
' Programs the button to throw an exception when clicked.
Private Sub button1_Click(sender As object, e As System.EventArgs)
Throw New ArgumentException("The parameter was invalid")
End Sub
<STAThread()> _
Shared Sub Main()
' Creates an instance of the methods that will handle the exception.
Dim eh As CustomExceptionHandler = New CustomExceptionHandler()
' Adds the event handler to the event.
AddHandler Application.ThreadException, AddressOf eh.OnThreadException
' Runs the application.
Application.Run(new ErrorHandler())
End Sub
End Class
' Creates a class to handle the exception event.
Private Class CustomExceptionHandler
' Handles the exception event.
Public Sub OnThreadException(sender As object, t As ThreadExceptionEventArgs)
Dim result As DialogResult = System.Windows.Forms.DialogResult.Cancel
Try
result = Me.ShowThreadExceptionDialog(t.Exception)
Catch
Try
MessageBox.Show("Fatal Error", "Fatal Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop)
Finally
Application.Exit()
End Try
End Try
' Exits the program when the user clicks Abort.
If (result = System.Windows.Forms.DialogResult.Abort) Then
Application.Exit()
End If
End Sub
' Creates the error message and displays it.
Private Function ShowThreadExceptionDialog(e As Exception) As DialogResult
Dim errorMsg As StringWriter = New StringWriter()
errorMsg.WriteLine("An error occurred please contact the adminstrator with the following information:")
errorMsg.WriteLine("")
errorMsg.WriteLine(e.Message)
errorMsg.WriteLine("")
errorMsg.WriteLine("Stack Trace:")
errorMsg.WriteLine(e.StackTrace)
Return MessageBox.Show(errorMsg.ToString(), "Application Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop)
End Function
End Class
// Creates a class to throw the error.
public class ErrorHandler : System.Windows.Forms.Form {
// Inserts the code to create a form with a button.
// Programs the button to throw an exception when clicked.
private void button1_Click(object sender, System.EventArgs e) {
throw new ArgumentException("The parameter was invalid");
}
public static void Main(string[] args) {
// Creates an instance of the methods that will handle the exception.
CustomExceptionHandler eh = new CustomExceptionHandler();
// Adds the event handler to to the event.
Application.ThreadException += new ThreadExceptionEventHandler(eh.OnThreadException);
// Runs the application.
Application.Run(new ErrorHandler());
}
}
// Creates a class to handle the exception event.
internal class CustomExceptionHandler {
// Handles the exception event.
public void OnThreadException(object sender, ThreadExceptionEventArgs t)
{
DialogResult result = DialogResult.Cancel;
try
{
result = this.ShowThreadExceptionDialog(t.Exception);
}
catch
{
try
{
MessageBox.Show("Fatal Error", "Fatal Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop);
}
finally
{
Application.Exit();
}
}
// Exits the program when the user clicks Abort.
if (result == DialogResult.Abort)
Application.Exit();
}
// Creates the error message and displays it.
private DialogResult ShowThreadExceptionDialog(Exception e) {
string errorMsg = "An error occurred please contact the adminstrator with the following information:\n\n";
errorMsg = errorMsg + e.Message + "\n\nStack Trace:\n" + e.StackTrace;
return MessageBox.Show(errorMsg, "Application Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop);
}
}
// Creates a class to throw the error.
public:
ref class ErrorHandler: public System::Windows::Forms::Form
{
// Inserts the code to create a form with a button.
// Programs the button to throw an exception when clicked.
private:
void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
throw gcnew ArgumentException( "The parameter was invalid" );
}
public:
static void Main()
{
// Creates an instance of the methods that will handle the exception.
CustomExceptionHandler ^ eh = gcnew CustomExceptionHandler;
// Adds the event handler to to the event.
Application::ThreadException += gcnew ThreadExceptionEventHandler( eh, &Form1::CustomExceptionHandler::OnThreadException );
// Runs the application.
Application::Run( gcnew ErrorHandler );
}
};
// Creates a class to handle the exception event.
internal:
ref class CustomExceptionHandler
{
// Handles the exception event.
public:
void OnThreadException( Object^ /*sender*/, ThreadExceptionEventArgs^ t )
{
System::Windows::Forms::DialogResult result = ::DialogResult::Cancel;
try
{
result = this->ShowThreadExceptionDialog( t->Exception );
}
catch ( Exception^ )
{
try
{
MessageBox::Show( "Fatal Error", "Fatal Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
}
finally
{
Application::Exit();
}
}
// Exits the program when the user clicks Abort.
if ( result == ::DialogResult::Abort )
{
Application::Exit();
}
}
// Creates the error message and displays it.
private:
System::Windows::Forms::DialogResult ShowThreadExceptionDialog( Exception^ e )
{
String^ errorMsg = "An error occurred please contact the adminstrator with the following information:\n\n";
errorMsg = String::Concat( errorMsg, e->Message, "\n\nStack Trace:\n", e->StackTrace );
return MessageBox::Show( errorMsg, "Application Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
}
};
// Creates a class to throw the error.
public static class ErrorHandler extends System.Windows.Forms.Form
{
// Inserts the code to create a form with a button.
// Programs the button to throw an exception when clicked.
private void button1_Click(Object sender, System.EventArgs e)
{
throw new ArgumentException("The parameter was invalid");
} //button1_Click
public static void main(String[] args)
{
// Creates an instance of the methods that will handle
// the exception.
CustomExceptionHandler eh = new CustomExceptionHandler();
// Adds the event handler to to the event.
Application.add_ThreadException(
new ThreadExceptionEventHandler(eh.OnThreadException));
// Runs the application.
Application.Run(new ErrorHandler());
} //main
} //ErrorHandler
// Creates a class to handle the exception event.
static class CustomExceptionHandler
{
// Handles the exception event.
public void OnThreadException(Object sender, ThreadExceptionEventArgs t)
{
DialogResult result = DialogResult.Cancel;
try {
result = this.ShowThreadExceptionDialog(t.get_Exception());
}
catch (System.Exception exp) {
try {
MessageBox.Show("Fatal Error", "Fatal Error",
MessageBoxButtons.AbortRetryIgnore,
MessageBoxIcon.Stop);
}
finally {
Application.Exit();
}
}
// Exits the program when the user clicks Abort.
if (result.Equals(DialogResult.Abort)) {
Application.Exit();
}
} //OnThreadException
// Creates the error message and displays it.
private DialogResult ShowThreadExceptionDialog(System.Exception e)
{
String errorMsg = "An error occurred please contact the"
+ " administrator with the following information:\n\n";
errorMsg = errorMsg + e.get_Message() + "\n\nStack Trace:\n"
+ e.get_StackTrace();
return MessageBox.Show(errorMsg, "Application Error",
MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop);
} //ShowThreadExceptionDialog
} //CustomExceptionHandler
public static void main(String[] args)
{
ErrorHandler.main(args);
}//main