.NET End vs Form.Close() vs Application.Exit Clean

问题:

sometimes, when I use Form.close() when debugging my program, although the form is closed, the application is still running. I noticed this behaviour when using the msgbox function.

I have no thread nor timer running, so what is the best way to close a .NET app? I am using VB.NET.

Thanks

回答1:

The situation you describe is pretty fishy. Whenever you close your program's startup form, the entire application should quit automatically, including closing all other open forms. Make sure that you're closing the correct form, and you should not experience any problems.

The other possibility is that you've changed your project (using its Properties page) not to close until all open windows have been closed. In this mode, your application will not exit until the last remaining open form has been closed. If you've chosen this setting, you have to make sure that you call the Close method of all forms that you've shown during the course of application, not just the startup/main form.

The first setting is the default for a reason, and if you've changed it, you probably want to go fix it back.
It is by far the most intuitive model for normal applications, and it prevents exactly the situation you describe. For it to work properly, make sure that you have specified your main form as the "Startup form" (rather than a splash screen or log-in form).

The settings I'm talking about are highlighted here:

   

But primarily, note that you should never have to call Application.Exit in a properly-designed application. If you find yourself having to do this in order for your program to close completely, then you are doing something wrong. Doing it is not a bad practice in itself, as long as you have a good reason. The other two answers fail to explain that, and thus I feel are incomplete at best.

回答2:

In .Net 1.1 and earlier, Application.Exit was not a wise choice and the MSDN docs specifically recommended against it because all message processing stopped immediately.

In later versions however, calling Application.Exit will result in Form.Close being called on all open forms in the application, thus giving you a chance to clean up after yourself, or even cancel the operation all together.

回答3:

If you are in a loop (Do While, For, ...) and you call Me.Close(), you should follow with an Exit command (Exit Do, ...) or a Return() to force the message processing to terminate properly. I caught programs hanging due to this.

回答4:

Form.Close() is use to close an instance of a Form with in .NET application it does not kill the entire application. Application.exit() kills your application.

回答5:

Application.Exit() kills your application but there are some instances that it won't close the application.

End is better than Application.Exit().

回答6:

Just put "End" keyword in your code.

Sub Form_Load()
  Dim answer As MsgBoxResult
  answer = MsgBox("Do you want to quit now?", MsgBoxStyle.YesNo)
  If answer = MsgBoxResult.Yes Then
      MsgBox("Terminating program")
      End 
  End If 
End Sub