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System.NullReferenceException

Discussion in 'C#' started by tanvirtonu, Aug 24, 2007.

  1. tanvirtonu

    tanvirtonu New Member

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    f I just add a simple textbox/richtext box in C# design window and run it, An exception occures- " System.NullReferenceException"

    My code frm the code window is as follows-
    Code:
    using System;
    using System.Drawing;
    using System.Collections;
    using System.ComponentModel;
    using System.Windows.Forms;
    using System.Data;
    
    namespace TestDemo2
    {
    	/// <summary>
    	/// Summary description for Form1.
    	/// </summary>
    	public class Form1 : System.Windows.Forms.Form
    	{
    		private System.Windows.Forms.RichTextBox richTextBox1;
    		/// <summary>
    		/// Required designer variable.
    		/// </summary>
    		private System.ComponentModel.Container components = null;
    
    		public Form1()
    		{
    			//
    			// Required for Windows Form Designer support
    			//
    			InitializeComponent();
    
    			//
    			// TODO: Add any constructor code after InitializeComponent call
    			//
    		}
    
    		/// <summary>
    		/// Clean up any resources being used.
    		/// </summary>
    		protected override void Dispose( bool disposing )
    		{
    			if( disposing )
    			{
    				if (components != null)
    				{
    					components.Dispose();
    				}
    			}
    			base.Dispose( disposing );
    		}
    
    		#region Windows Form Designer generated code
    		/// <summary>
    		/// Required method for Designer support - do not modify
    		/// the contents of this method with the code editor.
    		/// </summary>
    		private void InitializeComponent()
    		{
    			//Exception shows here- Highlighted after compile
    			this.richTextBox1 = new System.Windows.Forms.RichTextBox();
    
    			this.SuspendLayout();
    			//
    			// richTextBox1
    			//
    			this.richTextBox1.Location = new System.Drawing.Point(128, 40);
    			this.richTextBox1.Name = "richTextBox1";
    			this.richTextBox1.TabIndex = 0;
    			this.richTextBox1.Text = "richTextBox1";
    			//
    			// Form1
    			//
    			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
    			this.ClientSize = new System.Drawing.Size(456, 286);
    			this.Controls.AddRange(new System.Windows.Forms.Control[] {
    				this.richTextBox1});
    				this.Name = "Form1";
    				this.Text = "Form1";
    				this.Load += new System.EventHandler(this.Form1_Load);
    				this.ResumeLayout(false);
    
    		}
    		#endregion
    
    		/// <summary>
    		/// The main entry point for the application.
    		/// </summary>
    		[STAThread]
    		static void Main()
    		{
    			Application.Run(new Form1());
    		}
    
    		private void Form1_Load(object sender, System.EventArgs e)
    		{
    
    		}
    	}
    }
    
    After I run the same code the following message is shown-

    "An unhandled exception of type 'System.NullReferenceException' occurred in system.windows.forms.dll

    Additional information: Object reference not set to an instance of an object. "

    It highlights the following line of the code-

    "this.richTextBox1 = new System.Windows.Forms.RichTextBox();"


    IT IS really getting on my nerves.What the hell is this exception about. I didnt write a single code in it. I did it frm design window. THen why do they show such an exception. What else to do to get it right. PLs help me.
     
    Last edited by a moderator: Aug 24, 2007
  2. shabbir

    shabbir Administrator Staff Member

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    I am not sure why there is an error but it looks like you have just used the Generated code and nothing of your own.
     
  3. tanvirtonu

    tanvirtonu New Member

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    Brother where the .Net software cant make it out with its own generated code,You r telling me to add my code. :eek: If it cant run a simple program made/coded all by itself, there is no use writing my code.
     
  4. tanvirtonu

    tanvirtonu New Member

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    One thing is dat I hav two operating systems.One in drive c and another one(XP)is in drive D and I have installed .Net in XP, I mean drive D. But in Xp I installed MS.Net in drive E bcos there was little space in the system drive-D. Is it making anu problem. I even reinstalled .Net and tried again just after adding a richtextbox.It says the same thing-

    "An unhandled exception of type 'System.NullReferenceException' occurred in system.windows.forms.dll

    Additional information: Object reference not set to an instance of an object. "

    See the problem is in the system.windows.forms.dll.
    I dont know what it means. Whatever I add makes no problem except for RichTextBox-this is the main problem of every RICH!! object of the world
     
  5. shabbir

    shabbir Administrator Staff Member

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    Try to read the replies. If you are not a good reader you should be trying it out of your own. I have told just the opposite.
     

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