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c# exception

Ovidiu Roman

Ovidiu Roman

May 20 2014 4:57 PM
841
Greetings !
I am working on a project in which i have to transfer a few values between forms,but i get an exception when running the code. I have another forms other than the main form and i am trying to transfer the value which i am reading from the user in a textbox in the main form to a label in the second form.
 Could someone point me in the right direction or give me a clue as to how to solve this exception.
The code for the first form (in which i read the data from the user) is as it follows :
 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace interform_communication
{
   public partial class Form1 : Form
   {
      // add a delegate
      public delegate void usrUpdateHandler(object sender, usrUpdateEventArgs e);//IdentityUpdateEventArgs
      // add an event of the delegate type
      public event usrUpdateHandler usrUpdated;
      public Form1()
      {
         InitializeComponent();
      }
      private void button1_Click(object sender, EventArgs e)
      {
         Form2 newf = new Form2();
         string sNewUsr=textBox1.Text;
         usrUpdateEventArgs args = new usrUpdateEventArgs(sNewUsr);
         usrUpdated(this,args);//eroare aici(object reference not set to an instance of an object)
         this.Dispose();
         newf.Show();
      }
}
public class usrUpdateEventArgs : System.EventArgs
{
   private string mUser;
   public usrUpdateEventArgs(string sUser)
   {
      this.mUser = sUser;
   }
   public string user
   {
      get
      {
         return mUser;
      }
   }
}
 
And the code for the second form (in which i display the string from the first form) looks like this :
 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace interform_communication
{
   public partial class Form2 : Form
   {
      public Form2()
      {
         InitializeComponent();
      }
      private void Form2_Load(object sender, usrUpdateEventArgs e)
      {
         //string txtUser;
         Form1 f=new Form1();
         f.usrUpdated += new Form1.usrUpdateHandler(Form2_Load);
         label1.Text = e.user;
       }
   }
}

 These are some screenshots with the design of the project and the exception which i get when i test my code :
1)The exception that i get
 
 
2)The first form
 
 
3)The second form
 
 
 
The exception appears after i enter text in the textbox in form 1 and press Submit.
Thank you very much for your time !

Answers (4)