Subject: RE: System.NullReferenceException
Date: Thu, 3 Jul 2003 07:10:32 -0700
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Here is the code; I will mark the line where the execution
stops with <====
Also, I have included the contents of the Debug window
following the code.
============================ CODE ======================
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace AuthorsWinClient
{
/// <summary>
/// Summary description for Form1.
/// </summary>
public class frmMain : System.Windows.Forms.Form
{
private System.Windows.Forms.DataGrid
dataGrid1;
private System.Windows.Forms.Button
SaveData;
private System.Windows.Forms.Button
LoadData;
private
AuthorsWinClient.localhost.authors1 AuthorData;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container
components = null;
public frmMain()
{
//
// 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()
{
this.dataGrid1 = new
System.Windows.Forms.DataGrid();
this.AuthorData = new
AuthorsWinClient.localhost.authors1();
this.SaveData = new
System.Windows.Forms.Button();
this.LoadData = new
System.Windows.Forms.Button();
((System.ComponentModel.ISupportInitialize)
(this.dataGrid1)).BeginInit();
((System.ComponentModel.ISupportInitialize)
(this.AuthorData)).BeginInit();
this.SuspendLayout();
//
// dataGrid1
//
this.dataGrid1.DataMember
= "authors";
this.dataGrid1.DataSource =
this.AuthorData;
this.dataGrid1.HeaderForeColor =
System.Drawing.SystemColors.ControlText;
this.dataGrid1.Location = new
System.Drawing.Point(8, 8);
this.dataGrid1.Name = "dataGrid1";
this.dataGrid1.Size = new
System.Drawing.Size(344, 184);
this.dataGrid1.TabIndex = 0;
//
// AuthorData
//
this.AuthorData.DataSetName
= "authors1";
this.AuthorData.Locale = new
System.Globalization.CultureInfo("en-US");
//
// SaveData
//
this.SaveData.Location = new
System.Drawing.Point(216, 208);
this.SaveData.Name = "SaveData";
this.SaveData.Size = new
System.Drawing.Size(96, 24);
this.SaveData.TabIndex = 1;
this.SaveData.Text = "Save";
this.SaveData.Click += new
System.EventHandler(this.SaveData_Click);
//
// LoadData
//
this.LoadData.Location = new
System.Drawing.Point(40, 208);
this.LoadData.Name = "LoadData";
this.LoadData.Size = new
System.Drawing.Size(80, 24);
this.LoadData.TabIndex = 2;
this.LoadData.Text = "Load";
this.LoadData.Click += new
System.EventHandler(this.LoadData_Click);
//
// frmMain
//
this.AutoScaleBaseSize = new
System.Drawing.Size(5, 13);
this.ClientSize = new
System.Drawing.Size(360, 245);
this.Controls.Add(this.LoadData);
this.Controls.Add(this.SaveData);
this.Controls.Add(this.dataGrid1);
this.Name = "frmMain";
this.Text = "Form Main";
((System.ComponentModel.ISupportInitialize)
(this.dataGrid1)).EndInit();
((System.ComponentModel.ISupportInitialize)
(this.AuthorData)).EndInit();
this.ResumeLayout(false);
}
#endregion
/// <summary>
/// The main entry point for the
application.
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new frmMain());
} <==== Exception Thrown
private void LoadData_Click(object sender,
System.EventArgs e)
{
AuthorsWinClient.localhost.AuthorsService ws =
new
AuthorsWinClient.localhost.AuthorsService();
ws.Credentials =
System.Net.CredentialCache.DefaultCredentials;
AuthorData.Merge(ws.GetAuthors());
}
private void SaveData_Click(object sender,
System.EventArgs e)
{
AuthorsWinClient.localhost.AuthorsService ws =
new
AuthorsWinClient.localhost.AuthorsService();
ws.Credentials =
System.Net.CredentialCache.DefaultCredentials;
AuthorsWinClient.localhost.authors1 diffAuthors =
new
AuthorsWinClient.localhost.authors1();
diffAuthors.Merge
(AuthorData.GetChanges());
diffAuthors = ws.UpdateAuthors
(diffAuthors);
AuthorData.Merge(diffAuthors);
}
}
}
======================= DEBUG ==========================
'DefaultDomain':
Loaded 'c:\winnt\microsoft.net\framework\v1.1.4322
\mscorlib.dll', No symbols loaded.
'AuthorsWinClient': Loaded 'C:\Documents and
Settings\tdaniel\My Documents\Visual Studio
Projects\AuthorWebService\AuthorsWinClient\bin\Debug\Auth or
sWinClient.exe', Symbols loaded.
'AuthorsWinClient.exe':
Loaded 'c:\winnt\assembly\gac\system.windows.forms\1.0.50 00
.0__b77a5c561934e089\system.windows.forms.dll', No symbols
loaded.
'AuthorsWinClient.exe':
Loaded 'c:\winnt\assembly\gac\system\1.0.5000.0__b77a5c56 19
34e089\system.dll', No symbols loaded.
'AuthorsWinClient.exe':
Loaded 'c:\winnt\assembly\gac\system.drawing\1.0.5000.0__ b0
3f5f7f11d50a3a\system.drawing.dll', No symbols loaded.
'AuthorsWinClient.exe':
Loaded 'c:\winnt\assembly\gac\system.data\1.0.5000.0__b77 a5
c561934e089\system.data.dll', No symbols loaded.
'AuthorsWinClient.exe':
Loaded 'c:\winnt\assembly\gac\system.xml\1.0.5000.0__b77a 5c
561934e089\system.xml.dll', No symbols loaded.
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.
Unhandled Exception: System.NullReferenceException: Object
reference not set to an instance of an object.
at System.Windows.Forms.SafeNativeMethods.ShowWindow
(HandleRef hWnd, Int32 nCmdShow)
at System.Windows.Forms.Control.SetVisibleCore (Boolean
value)
at System.Windows.Forms.Form.SetVisibleCore(Boolean
value)
at System.Windows.Forms.Control.set_Visible(Boolean
value)
at
System.Windows.Forms.ThreadContext.RunMessageLoopInner
(Int32 reason, ApplicationContext context)
at System.Windows.Forms.ThreadContext.RunMessageLoop
(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at AuthorsWinClient.frmMain.Main() in c:\documents and
settings\tdaniel\my documents\visual studio
projects\authorwebservice\authorswinclient\form1.cs:line
121The program '[3084] AuthorsWinClient.exe' has exited
with code 0 (0x0).
-----Original Message-----
Can you post the rest of your code? Without it, it's
difficult to tell
what's going on....
Thanks,
- bliz
--
Jim Blizzard
Sr .NET Developer Evangelist
Microsoft
Your Potential. Our Passion.
This posting is provided "AS IS" with no warranties, and
confers no rights.
Please reply to newsgroups only, so that others may
benefit. Thanks.
--------------------
Content-Class: urn:content-classes:message
From: "Terrence" <
[email protected]>
Sender: "Terrence" <
[email protected]>
Subject: System.NullReferenceException
Date: Wed, 2 Jul 2003 20:14:49 -0700
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I am doing some of the C# walkthroughs to transition
from
VB to C#. When I try to execute
static void Main()
{
Aplication.Run(new Form1())
}
I raise a 'System.NullReferenceException" in
system.windows.forms.dll
I am sure this is a simple fix, but I cannot find a
answer.
Terrence
.
