How to updated the value of a textbox in C#

Question

1.00/5 (1 vote)

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Hi I'm trying to update a textbox, but it doesn't work.
The value from <do something="" here=""> should immitiately be updated into textbox2.

It compiles fine, but textbox is never updated !

br
Nikolaj
--------------------------------------------------------------------------------------

C#

namespace Excel_form
{
    
public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {

            excel.excel_init(textBox1.Text.ToString());
           
        }

       
        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            
        }

      
        public delegate void TextBoxDelegate(string message);

        public void UpdatingTextBox(string msg)
        {
            if (textBox2.InvokeRequired)
                textBox2.Invoke(new TextBoxDelegate(UpdatingTextBox), new object[] { msg });
            else
            {
                textBox2.Text = msg;
            }

            
        }

    }



public static class excel
{

 public static string excel_getCellValue(string lookFor)
        {
            
          do something here (value comes from here)    ............
........................
.....................

                Form1 fm1 = new Form1();
                fm1.UpdatingTextBox(value);
        }

}

}

Posted 11-Sep-14 5:33am

Nikolaj jensen

Updated 11-Sep-14 5:52am

ChauhanAjay

v2

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Comments

[no name] 11-Sep-14 11:41am

What is this? Why are you creating a new instance of Form1, updating the textbox and then immediately destroying it?

CPallini 11-Sep-14 12:01pm

Well spotted, my virtual 5.

ZurdoDev 11-Sep-14 11:46am

Just debug it. Should be easy to find.

Kishore Pogaru 11-Sep-14 11:58am

When do you want to populate the text? If you create a new Form1 on the fly it will not update the existing forms content. Also i don't see you are calling excel_getCellValue method in your code

3 solutions

Solution 1

As Wes Aday suggested, you are wrongly creating a new instance of Form1 in your excel_getCellValue method.
You have to call the UpdatingTextBox method of the existing Form1 instance.

Posted 11-Sep-14 6:01am

CPallini

Solution 2

:sigh:

Look at your code:

C#

Form1 fm1 = new Form1();
fm1.UpdatingTextBox(value);

What does the new keyword do?
You know that: it creates a new instance of the class - which you then update to reflect the new value. That won't be reflected in the the current display because that is a different instance of the Form from the one you just created.

You need to get the excel class to update the actual display - which its best handled by providing a "Changed" event which the form handles and updates itself.
See here: Transferring information between two forms, Part 2: Child to Parent[^] - think of your form as the Parent, and your excel class as the Child, and it should explain how to do it.

Posted 11-Sep-14 6:03am

OriginalGriff

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Nikolaj jensen · Accepted Answer · 2014-09-11T21:44:00

Ok, the below code is working. Is that an acceptable solution (code practice wise)?

-------------------------------------------

namespace Excel_form
{

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{

}

private void button1_Click(object sender, EventArgs e)
{

Excel.Excel_init(this, textBox1.Text.ToString());

}

private void textBox1_TextChanged(object sender, EventArgs e)
{

}

private void textBox2_TextChanged(object sender, EventArgs e)
{

}

public delegate void TextBoxDelegate(string message);

public void UpdatingTextBox(string msg)
{
if (textBox2.InvokeRequired)
textBox2.Invoke(new TextBoxDelegate(UpdatingTextBox), new object[] { msg });
else
{
textBox2.Text = msg;
}

}

}

public static class Excel
{

public static string Excel_getCellValue(Form1 abc, string lookFor)
{

do something here (value comes from here) ............
........................
.....................

abc.UpdatingTextBox(value); // this is not working
}

}

}