Problem with Delegates

Aey Saelee

Hi all
I'm having a problem with delegate. In my project I have 2 forms, form1 and form2. From form1 I have a button there just for opening form2. And from form2 I have a text box there to enter an Int value. After getting a value from the text box I want to send it back to form1 and appear in a text box on form1.

I do this with a delegate but I don't know if my way is the way you use to solve this problem or not.

Here is my code:


Form1


 public delegate void TestDelegate(int i);
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 frmOpen = new Form2();            
            frmOpen.ShowDialog();
        }
        public void GetValueA(int i)
        {
            textBox1.Text = i.ToString();         
        }
    }


Form2

    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int b;
            b = Convert.ToInt32(textBox1.Text);
            
            Form1 frm1=new Form1();
            TestDelegate td = new TestDelegate(frm1.GetValueA);
            td(b);
            Close();
        }
    }

3 Replies

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Sunny Chen18y ago
Getting value from Form2 directly is straightforward. But I think it is better by using events because it reduces the risk of high coupling.

Following is the solution:

Form 1:

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

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 frm2 = new Form2();
            frm2.OnGetValue += new Form2.GetValueEventHandler(frm2_OnGetValue);
            frm2.Show();
        }

        void frm2_OnGetValue(int val)
        {
            MessageBox.Show(val.ToString());
        }
    }

Form2:

    public partial class Form2 : Form
    {
        public delegate void GetValueEventHandler(int val);
        public event GetValueEventHandler OnGetValue;

        protected void DoGetValue(int val)
        {
            if (OnGetValue != null)
                OnGetValue(val);
        }

        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int ret = 0;
            int.TryParse(textBox1.Text, out ret);
            DoGetValue(ret);
            Close();
        }
    }
0
Aey Saelee18y ago
Thank you very much.
0
Ali Zaidi18y ago
Just make the textbox modifier to public and then do like:

Form1:

namespace solutions

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

Form2 ob = new Form2();

ob.ShowDialog();

textBox1OnForm1.Text = ob.textBox1OnForm2.Text;

}

}

}

Form2:

namespace solutions

{

public partial class Form2 : Form

{

public Form2()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

this.Close();

}

}

}
0