Changing control properties on other forms

[AMP]

Hello,
I have an mdi program with a child form ("A") and another child ("B").
I want to change the text of a label on A by changing an item from a
combobox on B. I can code the comboBox1_Selec tedIndexChanged that is on
B but I dont know how to send that info to the label on A.I cant seem
to access A from B.
Help
Thanks
Mike

A.label from B. combobox.

[Bob Grommes]

Just set B's label to public rather than the default visibility -- you
can do it in the control properties.

Or, cleaner than that, I would usually create a public string property
in B and have that set the text property of the private control.
Remember that B is a class like any other, and its public interface
should be minimal and should not expose the internals ... so a simple
public property is the best way from an OO standpoint. The public
property remains constant even if you decide later that a different
control or multiple controls need to respond to the change of value.
And the client code in A need know nothing about the actual control or
its name or even whether the value set goes to a control at all ... it
just needs to concern itself with informing B of the change via a nice
generically named public property.

--Bob

AMP wrote:

Hello,
I have an mdi program with a child form ("A") and another child ("B").
I want to change the text of a label on A by changing an item from a
combobox on B. I can code the comboBox1_Selec tedIndexChanged that is on
B but I dont know how to send that info to the label on A.I cant seem
to access A from B.
Help
Thanks
Mike

A.label from B. combobox.

[AMP]

This is on Form 1
private void button1_Click(o bject sender, EventArgs e)
{
Form frm = new Form2();
frm.label1.Text = "Hello";
}
The label is on a different form (Form 2)
Why doesnt this work?
label1 is public
Thanks

[Michael C]

"AMP" <am******@gmail .com> wrote in message
news:11******** **************@ i40g2000cwc.goo glegroups.com.. .

This is on Form 1
private void button1_Click(o bject sender, EventArgs e)
{
Form frm = new Form2();
frm.label1.Text = "Hello";
}
The label is on a different form (Form 2)
Why doesnt this work?
label1 is public
Bob gave an excellent explanation but he missed out one really important
point, how to get the reference to the Form. The above code won't work
because you are creating a new form every time the button is clicked but not
showing it. You need some way for Form1 to be able to access Form2. Where in
your code now do you currently have the "new Form2()"? Where ever that is
you need to keep that reference and somehow give your form1 access to that.
eg, in your MDI form:

public static Form2 Form2;

MyMDIForm_Load( )
{
Form2 = new Form2();
Form2.MDIParent = this;
Form2.Show();
}

then in Form1:
private void button1_Click(o bject sender, EventArgs e)
{

MyMDIForm.Form2 .ChangeLabel("H ello");
}

Thanks

[Mark Harris]

It doesnt work because you are creating a new instance of Form2, not
modifying the form that already exists.

On Tue, 07 Mar 2006 10:24:05 +0800, AMP <am******@gmail .com> wrote:

This is on Form 1
private void button1_Click(o bject sender, EventArgs e)
{
Form frm = new Form2();
frm.label1.Text = "Hello";
}
The label is on a different form (Form 2)
Why doesnt this work?
label1 is public
Thanks

[AMP]

Heres the relevent code:
Here is how the 2 children are created.
On the MainForm:
private void optionsToolStri pMenuItem1_Clic k(object sender, EventArgs
e)
{
Form thisOptions = new Options();
thisOptions.Mdi Parent = this; ;
thisOptions.Sho w();
}

private void newToolStripMen uItem_Click(obj ect sender,
EventArgs e)
{
Form frm1 = new Form1();
frm1.MdiParent = this; ;
frm1.Show();
}
I click both of these to create the 2 forms.

This is on the Options Form:
private void comboBox1_Selec tedIndexChanged (object sender, EventArgs e)
{
keyof = (string)comboBo x1.SelectedItem ;
}

There is a label on frm1 which is my newly created Form1 that I want to
change the text value .
So the next line in the SelectedIndexCh anged above,I want to set the
text property to keyof.
I thought there werent any Form1's or Options until I create them in
the code above
Thanks,
Mike

[Bob Grommes]

Mike,

There indeed aren't any form1's, etc until you create them, but look at
what frm1 for example is scoped to. It's local to
newToolStripMen uItem_Click(), so it goes away as soon as that routine exits.

If you need frm1 available elsewhere than store it in (say) a private
field of the form you're coding from so that you can access that
instance later as needed.

--Bob

AMP wrote:

Heres the relevent code:
Here is how the 2 children are created.
On the MainForm:
private void optionsToolStri pMenuItem1_Clic k(object sender, EventArgs
e)
{
Form thisOptions = new Options();
thisOptions.Mdi Parent = this; ;
thisOptions.Sho w();
}

private void newToolStripMen uItem_Click(obj ect sender,
EventArgs e)
{
Form frm1 = new Form1();
frm1.MdiParent = this; ;
frm1.Show();
}
I click both of these to create the 2 forms.

This is on the Options Form:
private void comboBox1_Selec tedIndexChanged (object sender, EventArgs e)
{
keyof = (string)comboBo x1.SelectedItem ;
}

There is a label on frm1 which is my newly created Form1 that I want to
change the text value .
So the next line in the SelectedIndexCh anged above,I want to set the
text property to keyof.
I thought there werent any Form1's or Options until I create them in
the code above
Thanks,
Mike