How to Check If a Windows Form Is Already Open, and Close It If It Is

How to check if a windows form is already open, and close it if it is?

maybe this helps:

FormCollection fc = Application.OpenForms;

foreach (Form frm in fc)
{
//iterate through
     if (frm.Name == "YourFormName")
     {
         bFormNameOpen = true;
     }
}

Some code in the foreach to detect the specific form and it could be done. Untested though.

Found on http://bytes.com/topic/c-sharp/answers/591308-iterating-all-open-forms

How to check if form is open, if open close form?

Application.OpenForms contains opened forms. If form in this collection, then it is opened. Otherwise it is not opened (possibly closed).

if (Application.OpenForms.OfType<YouLikeHits_Settings>().Any())
    MessageBox.Show("Form is opened");
else
    MessageBox.Show("Form is not opened");

How to check if your form is already opened or not and close it

Forms have a .Visible property that is true if the form is visible.

Declare your form inside the class:

private OutObjects outObjects;

Initialize/launch it:

outObjects = new OutObjects();
outObjects.Show();

and later if you want to close it if it's open check the .Visible property:

if (outObjects != null && outObjects.Visible)
    outObjects.Close();

The proper way to check if a form is already shown?

Firstly you are creating a new instance of Form14 every time you have a new message.

Secondly Show and ShowDialog do two very different things:

Show just displays the form, whereas ShowDialog displays the form as a modal dialog. This means the user can't do anything else until they dismiss the form.

You need to have a single instance of the form and you can use the Visible property to determine whether it's shown or not. So you would have:

private Form14 frm14;

Then in the constructor:

frm14 = new Form14();

Then in your code:

if (!frm14.Visible)
{
    // Add the message
    frm14.Show();
} else{
    // Top
    frm14.BringToFront();
}

Check if form is Opened

You can try it like this:

 Imports System.Linq ' need to add 


If Application.OpenForms().OfType(Of Form2).Any Then
  MessageBox.Show("Opened")
Else
  Dim f2 As New Form2
  f2.Text = "form2"
  f2.Show()
End If

Check if form is opened and update if opened

A better approach would be to filter the OpenForms based on the form type:

var form2collection = Application.OpenForms.OfType<Form2>();

You can then loop over those, or if the collection is empty, open a new form. The advantage is that you aren't relying on the form name, but the actual class definition of the form, which is more reliable.

Additionally, I tend to avoid direct manipulation of controls from other code. I find it more reliable if others call a method, such as

public void setSomeControl(string value)
{
    this.controlName.Text = value;
}

then call

form2collection[0].setSomeControl("new value");

which allows your form to do all the housekeeping and the calling code can ignore those details.

How to check if Window is already open? Duplicate Windows

You could use .IsLoaded field or bind the .ContentRendered event

Edit 1 -

Window1:

public class Window1 : Window
{
    private Info info = null;
    private Boolean IsInfoOpened = false;

    protected void OpenInfo()
    {
        if (this.IsInfoOpened) return;
        this.info = new Info();
        this.info.ContentRendered += delegate { this.IsInfoOpened = true; };
        this.info.Closed += delegate { this.IsInfoOpened = false; }
        this.info.Show();
    }
}

Focusing on winform if already opened?

My guess is that the problem is that you're only actually looking at the first form - you've got a break statement in both parts of the if statement... and you're also just using the general Form type which is almost certainly inappropriate. You might want:

var form = Application.OpenForms.OfType<MyForm>().FirstOrDefault();
if (form != null)
{
    form.Activate();
}
else
{
    new MyForm().Show();
}

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