How to close the second form after back to the first form

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hello everyone ..
I have a program that content two form
the first form is the main form and is the form that the program will start form it
and the second form is the form that will show one time only to take to values and then will comeback to the first and the second will close
note :in the start the program will do one from two

1- show second form if the values not in the program , then close the second and go to the first.
2- show the first and counties on it if the program have the values .

Note: when the second form will appear the first form will be hide , then after program takes the values from the user the second form will close and the first form will show

in anther word if the user give to the program the values from before the second form will not appear ,just the first form will appear only

What I have tried:

Code of FORM1

SqlConnection con;
        public Form1()
        {
            InitializeComponent();
            con = new SqlConnection(@"server=.\;database=Super;Integrated Security=true");
            b();
 
        }

 private void b()
        {
            Open();
            String SqlQuery = "SELECT * from test";
            DataTable dt = new DataTable();
            dt = fetchData(SqlQuery);
            if (dt.Rows.Count == 0)
            {
                MessageBox.Show("incorect user");
                Form2 fm2 = new Form2();
                fm2.Show();
                this.Hide();
            }
        }

Code FORM2

SqlConnection con;
       public Form2()
       {
           InitializeComponent();
           con = new SqlConnection(@"server=.\;database=Super;Integrated Security=true");
           Open();
       }

       public void fn()
       {

           String SqlQuery = "SELECT * from test ";
           DataTable dt = new DataTable();
           dt = fetchData(SqlQuery);
           if (dt.Rows.Count != 0)
           {
               Application.OpenForms[0].Show();
               this.Close();

           }


       }

       private void button1_Click(object sender, EventArgs e)
       {

           string insertQuery = "INSERT INTO test( name, phone) VALUES" +
               "(" + (textBox1.Text) + "," + (textBox2.Text) + ")";
           ExcuteQuery(insertQuery);
           MessageBox.Show("DONE");

           fn();
       }

the error is when I start run the program the two forms appears to the screen and the second form cant close after show the first form appears

Posted 14-May-21 12:21pm

Hala Hani

Updated 15-May-21 2:06am

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Comments

[no name] 14-May-21 18:43pm

There seems no point in hiding Form1. It also seems Form2 is modal; you should use ShowDialog.

Hala Hani 14-May-21 19:20pm

@Gerry
but I don't want to use ShowDialog!

2 solutions

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RickZeeland · Answer 1 · 2021-05-14T19:52:00

Solution 1

Your problem is probably that form2 is only visible in the scope of method b().

Form2 fm2 = new Form2();

So it would be better to place the declaration above public Form1() like this:

private Form2 fm2;

public Form1()
{ ... }

And then use this in method b():

fm2 = new Form2();

Posted 14-May-21 19:52pm

RickZeeland

Comments

Hala Hani 15-May-21 5:38am

It did not work. There is still a problem. Form 1 and 2 open at the same time and also when finished taking values from form2 , form 2 does not disappear.

RickZeeland 15-May-21 6:17am

Did you modify the Program.cs file maybe?

Tony Hill · Answer 2 · 2021-05-15T02:06:00

Firstly you are running code from inside the Form1 constructor, the constructor is used to initialise the form NOT run code, if you want to run code when the form is created it should be done in the Load event.

Secondly you should really send an event from the second form to any other form listing that Form2 has loaded, here is where you should signal to Form1 that it needs to hide.

And as Gerry suggested you should be using the ShowDialog() rather than Show().

Using events will solve you problems

see below

Form1 Code example

public partial class Form1 : Form
{
    Form2 form2;

    public Form1()
    {
        InitializeComponent();
        //
        // I have wired up the events manually so that you can see what events are required
        //
        Load += Form1_Load;
    }

    private void Form1_Load(object sender, EventArgs e)
    {
         // remove comments below to populate the form1 text box

         // Form1TextBox.Text = "Some text";

        if (Form1TextBox.Text == string.Empty)
        {
            form2 = new Form2();
            //
            // Wire up event handlers to recieve events from form 2
            //
            form2.form2Opened += Form2HasOpened;
            form2.form2Closed += Form2HasClosed;
            form2.ShowDialog();
        }
    }

    // This will fire when form 2 has initialised
    private void Form2HasOpened(object sender, EventArgs e)
    {
        Hide();
    }

    // This will fire when form 2 is about to close
    private void Form2HasClosed(object sender, EventArgs e)
    {
        Show();
        Form1TextBox.Text = form2.Form2Data;
        form2.Dispose();
    }
}

Form2 Code Example

public partial class Form2 : Form
{
    public event EventHandler form2Closed;
    public event EventHandler form2Opened;

    public Form2()
    {
        InitializeComponent();

        //
        // I have wired up the events manually so that you can see what events are required
        //
        Load += Form2_Load;
        MyButtonClose.Click += MyButtonClose_Click;

    }

    private void Form2_Load(object sender, EventArgs e)
    {
        // check we have wired up listeners
        if (form2Opened != null)
        {
            // we should have something listening so invoke the event to let the listeners know we have loaded
            form2Opened.Invoke(this, new EventArgs());
        }
    }

    private void MyButtonClose_Click(object sender, EventArgs e)
    {
        Form2Data = Form2TextBox.Text;

        // check we have wired up listeners
        if (form2Closed != null)
        {
            // we should have something listening so invoke the event to let the listeners know we are closing
            form2Closed.Invoke(this, new EventArgs());
        }
    }

    public string Form2Data { get; set; }
}