CODEWITHSUNDEEP
c#textboxreference
StealthRT
StealthRT

Reputation: 10552

C# referencing textbox from another class

new at C# so be nice...

I am trying to send some text to a form textbox using the following code:

SettingsForm.cs

 namespace BluMote
 {
      public partial class SettingsForm : Form
      {
           public void send2Display(string whatWasSent)
           {
               this.rtbDisplay.Text = whatWasSent;
           }

           private void cmdOpen_Click(object sender, EventArgs e)
           {
               commToy.Parity = "None";
               commToy.StopBits = "One";
               commToy.DataBits = "8";
               commToy.BaudRate = "115000";
               commToy.PortName = "COM4";
               commToy.OpenPort();
           }
      .........
      }
 }

And i am (trying) calling it from another class like so:

namespace PCComm
{
    class CommunicationManager
    {
    #region OpenPort
    public bool OpenPort()
    {
        try
        {
            if (comPort.IsOpen == true) comPort.Close();
            comPort.BaudRate = int.Parse(_baudRate);
            comPort.DataBits = int.Parse(_dataBits);
            comPort.StopBits = (StopBits)Enum.Parse(typeof(StopBits), _stopBits);
            comPort.Parity = (Parity)Enum.Parse(typeof(Parity), _parity);
            comPort.PortName = _portName;
            comPort.Open();
            PCComm.frmMain form = new PCComm.frmMain();
            form.send2Display("test");
            return true;
        }
        catch (Exception ex)
        {
            DisplayData(MessageType.Error, ex.Message);
            return false;
        }
    }
    #endregion
}
}

And "test" does not display in the textbox field

But as you can see, its not working... What am i missing?

David

Upvotes: 2

Views: 2447

Answers (5)

Tom Studee
Tom Studee

Reputation: 10452

BluMote.SettingsForm.send2display = "test";

Should be:

BluMote.SettingsForm form = new BluMote.SettingsForm();
form.Show();
form.send2Display("test");

But this creates a new instance, probably not what you want. You want to change the text on the currently displayed form, so you need to pass the instance the method needs to act on into the OpenPort method:

namespace PCComm
{
    class CommunicationManager
    {
    #region OpenPort
    public bool OpenPort(BluMote.SettingsForm form)
    {
        try
        {
            if (comPort.IsOpen == true) comPort.Close();
            comPort.BaudRate = int.Parse(_baudRate);
            comPort.DataBits = int.Parse(_dataBits);
            comPort.StopBits = (StopBits)Enum.Parse(typeof(StopBits), _stopBits);
            comPort.Parity = (Parity)Enum.Parse(typeof(Parity), _parity);
            comPort.PortName = _portName;
            comPort.Open();
            //PCComm.frmMain form = new PCComm.frmMain();
            form.send2Display("test");
            return true;
        }
        catch (Exception ex)
        {
            DisplayData(MessageType.Error, ex.Message);
            return false;
        }
    }
    #endregion
}
}

Then, somewhere in Form1 (like the load event), you'll want to instantiate the class dependent on it.

CommunicationManager comm = new CommunicationManager();
comm.OpenPort(this);

Upvotes: 3

saus
saus

Reputation: 2174

send2Display is a method, you need to call it with a parameter, not assign to it.

BluMote.SettingsForm form = new BluMote.SettingsForm();
form.send2Display("test");

EDIT:

If you are calling the method from inside the SettingsForm class, then you don't need to create a new instance. Try:

this.send2Display("test");

EDIT Based on updated question:

The problem is that the form that you are creating in OpenPort() is not the one that is displayed on screen, so any updates to the textbox won't show on screen. Here are a few quick and dirty ways to remedy this:

  • Pass a reference to the textbox into your method. I don't recommend this approach, because you will end up with view dependencies in your model.
  • Return a string from OpenPort() and pass the return value to sendToDisplay.
  • Define a property LastMessage of type string in CommunicationManager and assign to it in OpenPort(). Then read from it in SettingsForm and pass its value to sendToDisplay.

Upvotes: 4

CharithJ
CharithJ

Reputation: 47600

There are few issues in your code.

  1. Calling a method like a property.

    BluMote.SettingsForm.send2display = "test"; // This is wrong

  2. Trying to access SettingsForm class members from another class like accessing static members.

First you have to parse SettingsForm instance to the 'Other Class'.

//In Other Class

private SettingsForm settingsForm;

// Get the instance as a parameter in Constructor (this is one of options)
public OtherClass(SettingsForm instanceOfSettingsForm)
{
    settingsForm = instanceOfSettingsForm;
}

//Now you can call send2Display method from OtherClass

settingsForm.send2Display("Test");

Upvotes: 1

Kratz
Kratz

Reputation: 4340

You have to have an instance of a form object to do that, like this:

BluMote.SettingsForm form = new BluMote.SettingsForm();
form.Show()
form.send2Display("test");

Upvotes: 3

David
David

Reputation: 16287

You might change the code below and see if it works:

public void send2Display(string whatWasSent)
{
     this.rtbDisplay.Text = whatWasSent;
     this.rtbDisplay.refresh();
}

Upvotes: 0

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