I just started programming with C# and I'm trying to get my windows form application to function properly. However, whenever I run it, it just opens up and closes immediately. Whenever I type similar code into Java, there's no problem with the GUI. Did I miss something small here?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
Form1_FormClosing();
}
private void Form1_FormClosing()
{
const string message =
"There's an updated version of this program available. Would you like to download now?";
const string caption = "Please update";
var result = MessageBox.Show(message, caption,
MessageBoxButtons.YesNo,
MessageBoxIcon.Question);
// If the no button was pressed ...
if (result == DialogResult.No)
{
MessageBox.Show("Program will close now. If you want to use this program please update to the newest version.", "Please update");
this.Close();
}
else if (result == DialogResult.Yes)
{
System.Diagnostics.Process.Start("http://www.google.com");
this.Close();
}
}
}
}
Don't call Form1_FormClosing(); within the Form1_Load. Not sure if you wanted that but both No and Yes will close the form. I suspect you have the Form1_Loadattached to theLoad` event of the form.
[Edit]
You comment that the message box is shown which will happen cause it is being displayed within the Load of the form. The form has not had a change to render itself.
What you're doing here is showing a message to the user telling him/her that a new version of the application is available.
Now, what choise does he/she have?
If the answer is no: You close the application
If the answer is yes: You close it too
That's exactly what you're doing here.
Please, make your question more clear so we can help you.
Try changing call MessageBox.Show(message, caption, ... to MessageBox.Show(this, message, caption, ... - that would make the message box modal to the form. Another thing to check is how you are showing your form - are you using default Main method generated by VS or have u made any changes to it?
You can try something of this sort
DialogResult result = MessageBox.Show(message, caption,
MessageBoxButtons.YesNo,
MessageBoxIcon.Question,
MessageBoxDefaultButton.Button1,
MessageBoxOptions.DefaultDesktopOnly);
If you want to end the application in Form_Load(). Use FormClosing() event of Form, and call this.Close();.
EXAMPLE:
private void Form1_Load(object sender, EventArgs e)
{
this.Close(); //this will call Form_Closing()
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
//do stuff
if (result == DialogResult.No)
{
e.Cancel = true; // if you don't want to close your form
}
else
{
// do stuff on closing form
}
}
What exactly is the problem??? Do you mean to say you are not able to view the message box itself or just the contents in it??
If the message box itself is not shown, then it means the Form1_Load event is not getting called properly. Try deleting the event and create it again by right clicking on the form ->Properties. In the event tab, click Load and then call the Form1_FormClosing method again inside the Load event.
Tried executing in my system and the form is working as expected.
Related
I've researched several common issue, like the message box displaying behind the form window, trying different wat to call them, however nothing seems to display them. I'm sure it's something simple I'm missing?
The application should open a form window with a listbox and some items, if nothing is selected and you click on the button it should display the "Please select and item form the list box" in a message box, but it does not.
Also it should display the "Are you sure you want to close?" message in a box when you x out of the forms window.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsDemos
{
public partial class Dialogs : Form
{
public Dialogs()
{
InitializeComponent();
}
private void Dialogs_Load(object sender, EventArgs e)
{
listBox1.Items.Add("Oranges");
listBox1.Items.Add("Grapes");
listBox1.Items.Add("Bananas");
listBox1.Items.Add("Peaches");
}
private void button1_Click(object sender, EventArgs e)
{
if (listBox1.SelectedIndex == -1)
{
var msg = "Please select an item from the list box";
MessageBox.Show(msg, this.Text);
return;
}
else
{
label1.Text = listBox1.Text;
}
}
private void Dialogs_FormClosing(object sender, FormClosingEventArgs e)
{
var msg = "Are you sure you want to close?";
if (MessageBox.Show(msg, this.Text, MessageBoxButtons.YesNo) == DialogResult.No)
{
e.Cancel = true;
}
}
}
}
Instead of having your Dialogs class subscribe to its own events like Load and FormClosing it's cleaner (and may be less error-prone) to simply override the OnLoad and OnFormClosing methods that are causing the events to be fired in the first place. I tested this code and it produces the expected outcomes described in your post.
public Dialogs()
{
InitializeComponent();
}
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e); // <== The `Load` event you were subscribing to is fired here.
listBox1.Items.Add("Oranges");
listBox1.Items.Add("Grapes");
listBox1.Items.Add("Bananas");
listBox1.Items.Add("Peaches");
// Subscribing to the `Click` event here as an
// alternative to relying on the Designer to do it.
button1.Click += onButton1Clicked;
}
protected override void OnFormClosing(FormClosingEventArgs e)
{
base.OnFormClosing(e); // <== The `FormClosing` event is fired here.
var msg = "Are you sure you want to close?";
if (MessageBox.Show(msg, this.Text, MessageBoxButtons.YesNo) == DialogResult.No)
{
e.Cancel = true;
}
}
I also agree with the other answer posted so far, that the button's Click event doesn't seem to be linked. It may be less error prone to subscribe to this event as shown above in the OnLoad method.
private void onButton1Clicked(object sender, EventArgs e)
{
if (listBox1.SelectedIndex == -1)
{
var msg = "Please select an item from the list box";
MessageBox.Show(msg, this.Text);
return;
}
else
{
label1.Text = listBox1.Text;
}
}
This should work. Are you sure you have an event linked to the method?
// in file Dialogs.Designer.cs or in Form Property/Events tool window
this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.Dialogs_FormClosing);
I have a list of "projects" with some informations in textBoxs for each project. The user can select a project then modify the informations and click on save button after that.
If I changes selected project without save the modifications, a Yes/No MessageBox appear:
DialogResult dialogResult = MessageBox.Show(
"Do you want to save changes ?",
"Title",
MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
//Click Yes
}
else
{
//Click No
}
I would to refresh all the project list (with my own Refresh() methode) after clicking on Yes/No button, but staying on the MessageBox until the refresh is done.
Is it possible?
The built in MessageBox class does not allow such complicated behaviour.
One way to do this is to create your own message box. Create a subclass of Form, add some labels and buttons. Expose some events like YesClicked and NoClicked.
In your main form, create an instance of your custom message box, subscribe to the events, and call ShowDialog on it.
After the refresh is done, you can call Close or Dispose on your custom message box to close it.
Try creating a custom message box. I commented the code, let me know if you need clarification
public static class MessageBoxResult
{
public static int dialogResult; // <== i use this value to determine what button was pressed
}
// your custom message box form code
public partial class CustomMsgBox : Form
{
public CustomMsgBox()
{
InitializeComponent();
}
public void show(string pos0, string pos1, string pos2, string message) //<=== initializing the message box with the values from your main code
{
button1.Text = pos0;
button2.Text = pos1;
button3.Text = pos2;
label1.Text = message;
}
// message box events to set the static field incase a button on the custom form was changed
private void button1_Click(object sender, EventArgs e)
{
MessageBoxResult.dialogResult = 0;
this.Close();
}
private void button2_Click(object sender, EventArgs e)
{
MessageBoxResult.dialogResult = 1;
this.Close();
}
private void button3_Click(object sender, EventArgs e)
{
MessageBoxResult.dialogResult = 2;
this.Close();
}
}
//usage
{
MessageBoxResult.dialogResult = -1; // <== setting the static field to -1 to mean nothing was pressed
CustomMsgBox cMsgBox = new CustomMsgBox();
cMsgBox.show("your message");
cMsgBox.ShowDialog();
}
You can change what happends, based on what button is clicked, with the DialogResult
DialogResult dialogResult = MessageBox.Show(#"Some body", #"Title", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
// do stuff
}
No, a message box cannot do this. It's not meant to do this. It's meant to just display a message... in a box :)
What you can always do is create your own window that looks like a message box and behaves like a message box, but actually does things when you click the buttons.
I have this event in a new Form:
private void CrawlLocaly_FormClosed(object sender, FormClosedEventArgs e)
{
}
Im not sure if to use Closed or Closing.
The reason is that i want to check if the user shut down the program for example by just closing the application from the taskbar.
If he did close it from the taskbar mouse right click then close then i want it to close all the program and not only this Form.
How can i do it ?
Application.Exit();
Will shut down your application.
Im not really sure if you can detect if he closed it via rightmouse menu. As far as I know you can only see the reasons provided in the FormClosedEventArgs. FormClosing will provide you with same reasons.
Use this event:
private void Form_FormClosing(object sender, FormClosingEventArgs e)
{
if(e.CloseReason == CloseReason.UserClosing)
{
//close forms
Application.Exit();
}
}
There is no way to check whether user closed your form by clicking 'X' or through TaskBar or any other way as the result of CloseReason will always be CloseReason.UserClosing
Well I Stick with such issue also.
In mine app I have 2 forms, #1 main, #2 - for settings - if user close it i want to know save settings or not. Also if settings are null - close app not only form, if user click button save - I want to close (hide) #2 form.
So where is my solution we set tag value to 1 if click button save, so we will know "who" try to close form:
Predefined:
btnSave.Tag = 0;
On save button click event:
btnSave.Tag = 1;
this.Hide();
its will trigger onclose event:
private void frmLogin_FormClosing(object sender, FormClosingEventArgs e)
{
if (btnSave.Tag.ToString() == "0")
{
DialogResult dlg = MessageBox.Show("Do you want to exit without finished setup connection?", "Form", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
if (dlg == DialogResult.No)
{
e.Cancel = true;
}
else
{
e.Cancel = false;
this.Dispose();
Application.Exit();
}
}
else
{
this.Hide();
}
}
I have this form called MainForm.cs. When I click Enter The Progam button I display another form using the .ShowDialog() method.
In this new form called LoginBox.cs, I check if the entered credentials are valid and if they are I want my MainForm.cs to react with either a positive responde (the actual software form opens) or negative response a MessageBox alerting him of the failure.
It's a very simple use case, but I don't know how to solve this correctly and efficiently. Thank you.
private void button1_Click(object sender, EventArgs e)
{
LoginBox login = new LoginBox();
login.ShowDialog();
}
//And in the LoginBox.cs file:
private void button1_Click(object sender, EventArgs e)
{
if ((txtUser.Text == "admin") && (txtPassword.Text == "123"))
{
}
}
If you open the form with ShowDialog it returns a DialogResult which you can check in your main form.
LoginBox login = new LoginBox();
DialogResult dialogResult = login.ShowDialog();
if (dialogResult == DialogResult.OK)
{
// etc...
}
You can set the value of DialogResult in your LoginBox form:
DialogResult = DialogResult.OK;
Others have mentioned using DialogResult, which can work--but might be abused a bit in this use-case. Its intended purpose is to let the parent form know what the user did on a child form--did they click OK or Cancel? Did they click Retry or Abort? It's not intuitive that it should be used for authentication purposes.
So--what's better? Probably a combination...
Your LoginBox class is a Dialog, so returning a DialogResult should be expected--but should also only be used to indicate what the user did on the Form, not the outcome of the authentication.
I would suggest looking into the usage of some other dialogs, such as OpenFileDialog. It returns a DialogResult to specify whether to go ahead with the file opening, but it doesn't actually open the file until being explicitly told to do so. This means the consuming code has to both check the result and instruct the dialog to perform it's function, so it's not perfectly simple--but it's fairly conventional.
Here's an example of how I would suggest you use LoginBox:
private void button1_Click(object sender, EventArgs e)
{
LoginBox login = new LoginBox();
if (login.ShowDialog() == DialogResult.OK) // Let the user input their credentials and click OK or Cancel
{
if (!login.ValidateCredentials) // Perform the authentication with the collected credentials
{
MessageBox.Show("The specified Credentials were invalid!");
}
}
}
Add an Event to the LoginBox. Then have the MainForm handle that event. In the event handler proceed with the additional logic that you want to perform.
I cannot close one of my forms programmatically. Can someone help me?
Here's the code:
private void WriteCheck_Load(object sender, EventArgs e) {
SelectBankAccountDialog sbad = new SelectBankAccountDialog();
DialogResult result = sbad.ShowDialog();
if (result == DialogResult.Cancel) {
this.Close();
} else {
MessageBox.Show(result.ToString());
}
MessageBox.Show(sbad.bankaccountID.ToString());
}
As configurator mentioned (in comments), the form must be shown before it can be closed, so, instead of the Load event, you should be doing this in the Shown event instead.
If you don't want the form visible for the Dialog box, I guess you can wrap the event code in a Visible = false;
In summary, the basic code would be
private void WriteCheck_Shown(object sender, EventArgs e)
{
Visible = false;
SelectBankAccountDialog sbad = new SelectBankAccountDialog();
DialogResult result = sbad.ShowDialog();
if (result == DialogResult.Cancel) {
this.Close();
} else {
MessageBox.Show(result.ToString());
}
MessageBox.Show(sbad.bankaccountID.ToString());
Visible = true;
}
By calling Form.Close(), the form should close, but not until all waiting events have been processed. You also still have a chance to cancel the form closing in the FormClosing event.
First, you'll probably want to return after your call to this.Close(). If it still doesn't close, step through your code and see what is happening. You may have to set and check a "forciblyClose" flag and return from any other processing methods before it'll actually close.
The actual problem is that windows won't let a form close on it's load method. I have to show the dialog on construction, and then if the dialog result is cancel I have to throw an exception and catch the exception on form creation.
This place talks more about it