如何从第二个表单中的值更新活动的Windows表单文本框？

Question

I have a Windows Form (let's call it Form1 ) that opens a second windows form ( Form2 ) to make the user select something from a comboBox.

// create form1
var Form1 = new Form1();
Form1.Show();

// event to open form2
private void openForm2(object sender, EventArgs e)
{
    Form2 Form2= new Form2();
    Form2.Show();
}

After selecting an item in the comboBox, the user clicks on the "Update" button to update a textBox in Form1 with the selected value.

private void updateForm1(object sender, EventArgs e)
    {
        // Form1.textBox1 is not accessible
    }

I know how to pass a value from Form1 to Form2 , but how can I pass a value from Form2 back to the active Form1 ? I can't access the active Form1 without recreating the form.

Answer 1

I found the answer by passing an event handler.

// propertie in form1 to hold the form2 instance to get the value back
private Form2 _form2;
public Form2 form2
{
    get { return _form2; }
    set { this._form2= value; }
}

// opens the form1
var Form1 = new Form1();
Form1.Show();

// event to open form2
private void openForm2(object sender, EventArgs e)
{
    Form2 Form2= new Form2();
    Form2.FormClosing += new FormClosingEventHandler(getValueFromForm2);
    Form2.Show();

    this.form2 = Form2;
}

// event to retrieve the value and update textbox of form1
private void getValueFromForm2(object sender, FormClosingEventArgs e)
{
    Control ctrl = this.form2.Controls.Find("theControlWithTheValue", true)[0];

    // control is a listbox
    ListBox lbox = ctrl as ListBox;

    // update form1 textbox
    textBoxInForm1.Text = lbox.SelectedItem.ToString();
}