CODEWITHSUNDEEP
c#.netwinformslistbox
Elli
Elli

Reputation: 29

ListBox and WinForms application

I have a windows form1 application. This form1 has a click button. When the button is clicked some events handler are created in the click-button method. In the SendText event handler method I a create and show a second Form2 where i want to print a string value met in form1.

The problem is the fact that in my ListBox I see just one string and not all of them (I am consecutively sending strings). Why? Plus there are no additional Form2 forms created and shown when a new event handler arrives.

In Form1 this is the way i am calling form2: 

public void Send(string body, string name)
{
    Form2 form2 = new Form2(body);
    form2.Text = name;
    form2.ShowDialog ();
} 

public  void OnMessage(first val, second vall)
{
    send(string val1, string va2);
}

Form2 contains:

public Form2(string s)
{
    InitializeComponent();
    listBox1.Items.Add(s);
}

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
}

2 Questions:

  1. How can i create multiple Form2 forms each time the handler is activated (using threads, no?)?

  2. If first val is the same when a new handler arrives how can I activate the form2 that is already on the screen and add a new item in the ListBox1?

Please provide examples, if possible.

Thank you.

Upvotes: 0

Views: 349

Answers (4)

DarkSquirrel42
DarkSquirrel42

Reputation: 10257

if i got this right, you want:

  • a new form2 for each unique "name" param in Send(...)
  • all following calls to Send(...) with the same param "name" should add the string in the "body" param to the same list on the associated form2

what about this?

Dictionary<string,From2> myForm2s = new Dictionary<string,Form2>();

public void Send(string body, string name)
{
   Form2 frm = null;
   if(!myForm2s.tryGetValue(name,out frm))
   {
      frm = new Form2(body);
      myForm2s[name] = frm;
      frm.Text = name;
      frm.FormClosing += new FormClosingEventHandler(Form2_FormClosing);
      frm.Show();
   }
   else
   {
      frm.listBox1.Items.Add(body); // assuming listBox1 is public
      frm.Show();
      frm.BringToFront();
   }
}
void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
   e.Cancel = true;
   ((Form2)sender).Hide();
}

(code not tested...)

you will possibly want to handle the FormClosing event of Form2 ... cancel the event using the eventarg and call this.Hide() ... so a Form2 will still disappear if the user klicks the x but the form is still there, ready to be reshown when the next event adds something to it ...

Upvotes: 0

Yetti
Yetti

Reputation: 1710

Instead of using form2.ShowDialog();, you can use form2.Show();

This works because Show() is modeless, ShowDialog() is modal.

Here is an explanation of the differences.

For the second question, as others have said, you can add a form and the name with which it was initiated to a dictionary. Then, whenever you add another body value, you check the dictionary for a duplicate name value. If one exists, add the body value to the listbox of that particular form.

Upvotes: 1

axl g
axl g

Reputation: 622

Use a dictionary to store the opened Form2 ordered by name:

private Dictionary<string, Form2> forms = new Dictionary<string, Form2>();

public void Send(string body, string name)
{
    if(forms.ContainsKey(name))
    {
        forms[name].AddNewItem(body);
    }
    else{
        Form2 form2 = new Form2(body);
        form2.Text = name;
        forms.Add(name, form2);  
        form2.ShowDialog();
    }
}

And Form2 will contain:

public Form2(string s)
{
    InitializeComponent();
    listBox1.Items.Add(s);
}

public void AddNewItem(string s)
{
    listBox1.Items.Add(s);
}

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{ 
}

Hope this helps :)

Upvotes: 0

Nighil
Nighil

Reputation: 4129

try to make your form static

static Form2 form2;

public void Send(string body, string name)
{        
    form2 = new Form2(body);
    form2.Text = name;
    form2.ShowDialog();
}

Upvotes: 0

Related Questions