FormClosing 和 FormClosed 事件不起作用

Question

I'm developing a C# app And i need do some validations before the user close the form.

I tried to use the FormClosing event, but it didn't work, later I used the FormClosed event, but the same.

The problem is, when I click in the "close button" (on the top of the form) it doesn't do anything but i have the events in form properties and everything.

this is my code:

    private void Inicio_FormClosing_1(object sender, FormClosingEventArgs e)
    {
    //things I have to do
    //...
    //...

    if(bandera==true)
    Application.Exit();

    }

and

    private void Inicio_FormClosed_1(object sender, FormClosingEventArgs e)
    {
    //things I have to do
    //...
    //...

    if(bandera==true)
    Application.Exit();

    }

any idea?

Thank you

Answer 1

Both events should work fine. Just open a new project and do this simple test:

 private void Form1_Load(object sender, EventArgs e)
 {
     this.FormClosing += new FormClosingEventHandler(Inicio_FormClosing_1);
     this.FormClosed += new FormClosedEventHandler(Inicio_FormClosed_1);
 }

 private void Inicio_FormClosing_1(object sender, FormClosingEventArgs e)
 {
     //Things while closing

 }

 private void Inicio_FormClosed_1(object sender, FormClosedEventArgs e)
 {
     //Things when closed
 }

If you set break points in these methods, you would see that they are reached after the close button is clicked. It seems that there is some problem in your event-attaching code. For example: Inicio_FormClosed_1(object sender, FormClosingEventArgs e) is wrong, as far as it should take a FormClosedEventArgs argument; and thus this method is surely not associated with the FormClosed event (otherwise, the code wouldn't compile).

Answer 2

I found the mistake;

Here: (when I initialize my form)

    public Inicio()
    {
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.AutoScroll = true;

        this.ClientSize = new System.Drawing.Size(635, 332);
        this.StartPosition = FormStartPosition.CenterScreen;
        llenaForm(nombreFormulario);
        Application.EnableVisualStyles();

    }

All i needed was: InitializeComponent();
I deleted by mistake

It should be:

    public Inicio()
    {
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.AutoScroll = true;`

        InitializeComponent();//<<<<<<<<------------------- 

        this.ClientSize = new System.Drawing.Size(635, 332);
        this.StartPosition = FormStartPosition.CenterScreen;
        llenaForm(nombreFormulario);
        Application.EnableVisualStyles();
    }

Thank you so much guys!

Answer 3

In order to prevent the user from closing a form in response to certain validations, you need to set FormClosingEventArgs.Cancel = true .

For example:

private void Inicio_FormClosing_1(object sender, FormClosingEventArgs e)
{
    if (string.IsNullOrEmpty(txtSomethingRequired.Text))
    {
        MessageBox.Show("Something is required here!");
        if (txtSomethingRequired.CanFocus) txtSomethingRequired.Focus();
        e.Cancel = true;
        return;
    }
}

You can only do validations in the FormClosing event to prevent the form from closing; if you wait until FormClosed it is already too late.

Answer 4

I noticed you have an "_1" at the end of your method names. Did you rename these methods?

If so, your UI code(designer file) will need to be updated with these new method names.

You can put a breakpoint in these methods to see if they are getting called.

Answer 5

作为旁注，Form.Hide() 方法不会引发 form_closed 或 form_closed 事件

Answer 6

I also faced a similar problem, and it was provoked by using Dispose() . Make sure that you are using Close() to raise closing/closed events.