Re: Form disappearing - C# Discussion Boards

17-Apr-16 0:02

Hi All

Would appreciate some help on the following code which results in the form disappearing, rather than persisiting. Probably something really silly (code newbie, please be gentle).

using System.ComponentModel;
using System.Drawing;
using System.IO;
using System.Windows.Forms;

namespace TCPReader
{

public class frmConfiguration : System.Windows.Forms.Form
{
private void frmConfiguration_Load(object sender, System.EventArgs e)
{
}
private System.Windows.Forms.Button btnok;
private System.Windows.Forms.Button button2;
private System.ComponentModel.IContainer components;
private System.Windows.Forms.GroupBox groupBox1;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
public USBReader.readerqueue m_queue;
public USBReader.Socketclient m_sclient;
public System.Threading.Thread thread1;
public System.Threading.Thread threadClient;
private System.Windows.Forms.TextBox txtipaddres;
private System.Windows.Forms.TextBox txtportno;

private void btnok_Click(object sender, System.EventArgs e)
{
try
{
bool flag = txtipaddres.Text != "" && txtportno.Text != "";
if (!flag)
{
System.Windows.Forms.MessageBox.Show("Enter IP Address and Port No to Connet\n to the Node", "Node Control", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Asterisk);
Show();
}
else
{
System.IO.TextWriter textWriter = System.IO.File.CreateText(System.Windows.Forms.Application.StartupPath + "\\IPAddress.txt");
textWriter.WriteLine(txtportno.Text + ";" + txtipaddres.Text);
textWriter.Close();
DialogResult = System.Windows.Forms.DialogResult.OK;
Close();
}
}
catch (System.Exception e1)
{
}
}

private void button2_Click(object sender, System.EventArgs e)
{
DialogResult = System.Windows.Forms.DialogResult.Cancel;
Close();
}

private void Configuration_Load(object sender, System.EventArgs e)
{
bool flag = !System.IO.File.Exists(System.Windows.Forms.Application.StartupPath + "\\IPAddress.txt");
if (!flag)
{
System.IO.TextReader textReader = System.IO.File.OpenText(System.Windows.Forms.Application.StartupPath + "\\IPAddress.txt");
string s = textReader.ReadLine();
textReader.Close();
char[] chArr = new char[] { ';' };
string[] sArr = s.Split(chArr);
txtportno.Text = sArr[0];
txtipaddres.Text = sArr[1];
}
else
{
txtipaddres.Text = "";
txtportno.Text = "";
}

}

private void InitializeComponent()
{
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.btnok = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.groupBox1 = new System.Windows.Forms.GroupBox();
this.txtipaddres = new System.Windows.Forms.TextBox();
this.txtportno = new System.Windows.Forms.TextBox();
this.groupBox1.SuspendLayout();
this.SuspendLayout();
//
// label1
//
this.label1.AutoSize = true;
this.label1.Font = new System.Drawing.Font("Palatino Linotype", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.label1.ForeColor = System.Drawing.SystemColors.HotTrack;
this.label1.Location = new System.Drawing.Point(24, 36);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(73, 18);
this.label1.TabIndex = 2;
this.label1.Text = "IP Address";
//
// label2
//
this.label2.AutoSize = true;
this.label2.Font = new System.Drawing.Font("Palatino Linotype", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.label2.ForeColor = System.Drawing.SystemColors.HotTrack;
this.label2.Location = new System.Drawing.Point(42, 72);
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size(55, 18);
this.label2.TabIndex = 3;
this.label2.Text = "Port No";
//
// btnok
//
this.btnok.BackColor = System.Drawing.Color.AliceBlue;
this.btnok.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
this.btnok.Font = new System.Drawing.Font("Palatino Linotype", 9F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.btnok.ForeColor = System.Drawing.SystemColors.HotTrack;
this.btnok.Location = new System.Drawing.Point(103, 114);
this.btnok.Name = "btnok";
this.btnok.Size = new System.Drawing.Size(69, 23);
this.btnok.TabIndex = 3;
this.btnok.Text = "O&k";
this.btnok.UseVisualStyleBackColor = false;
this.btnok.Click += new System.EventHandler(this.btnok_Click);
//
// button2
//
this.button2.BackColor = System.Drawing.Color.AliceBlue;
this.button2.Cursor = System.Windows.Forms.Cursors.Default;
this.button2.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
this.button2.Font = new System.Drawing.Font("Palatino Linotype", 9F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.button2.ForeColor = System.Drawing.SystemColors.HotTrack;
this.button2.Location = new System.Drawing.Point(189, 114);
this.button2.Name = "button2";
this.button2.Size = new System.Drawing.Size(69, 23);
this.button2.TabIndex = 4;
this.button2.Text = "&Cancel";
this.button2.UseVisualStyleBackColor = false;
this.button2.Click += new System.EventHandler(this.button2_Click);
//
// groupBox1
//
this.groupBox1.Controls.Add(this.txtipaddres);
this.groupBox1.Controls.Add(this.label2);
this.groupBox1.Controls.Add(this.txtportno);
this.groupBox1.Controls.Add(this.label1);
this.groupBox1.Controls.Add(this.btnok);
this.groupBox1.Controls.Add(this.button2);
this.groupBox1.Font = new System.Drawing.Font("Palatino Linotype", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
this.groupBox1.ForeColor = System.Drawing.SystemColors.HotTrack;
this.groupBox1.Location = new System.Drawing.Point(23, 12);
this.groupBox1.Name = "groupBox1";
this.groupBox1.Size = new System.Drawing.Size(288, 158);
this.groupBox1.TabIndex = 8;
this.groupBox1.TabStop = false;
this.groupBox1.Text = "Configuration";
this.groupBox1.Enter += new System.EventHandler(this.groupBox1_Enter);
//
// txtipaddres
//
this.txtipaddres.BackColor = System.Drawing.SystemColors.Window;
this.txtipaddres.Location = new System.Drawing.Point(103, 36);
this.txtipaddres.Name = "txtipaddres";
this.txtipaddres.Size = new System.Drawing.Size(155, 25);
this.txtipaddres.TabIndex = 1;
this.txtipaddres.TextChanged += new System.EventHandler(this.txtipaddres_TextChanged);
//
// txtportno
//
this.txtportno.BackColor = System.Drawing.SystemColors.Window;
this.txtportno.Location = new System.Drawing.Point(103, 72);
this.txtportno.Name = "txtportno";
this.txtportno.Size = new System.Drawing.Size(155, 25);
this.txtportno.TabIndex = 2;
//
// frmConfiguration
//
this.AcceptButton = this.btnok;
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.BackColor = System.Drawing.Color.Snow;
this.ClientSize = new System.Drawing.Size(335, 197);
this.ControlBox = false;
this.Controls.Add(this.groupBox1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
this.Name = "frmConfiguration";
this.Load += new System.EventHandler(this.Configuration_Load);
this.groupBox1.ResumeLayout(false);
this.groupBox1.PerformLayout();
this.ResumeLayout(false);

}

protected override void Dispose(bool disposing)
{
bool flag = !disposing || (components == null);
if (!flag)
components.Dispose();
base.Dispose(disposing);
}

private void groupBox1_Enter(object sender, EventArgs e)
{

}

private void txtipaddres_TextChanged(object sender, EventArgs e)
{

}

} // class frmConfiguration

}</pre>

Regards
Active

OriginalGriff17-Apr-16 0:36

17-Apr-16 0:36

You don't tell us when it disappears, but if it's when you press a button then it's because you told it to:

private void btnok_Click(object sender, System.EventArgs e)
    {
    try
        {
        bool flag = txtipaddres.Text != &quot;&quot; &amp;&amp; txtportno.Text != &quot;&quot;;
        if (!flag)
            {
            System.Windows.Forms.MessageBox.Show(&quot;Enter IP Address and Port No to Connet\n to the Node&quot;, &quot;Node Control&quot;, System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Asterisk);
            Show();
            }
        else
            {
            System.IO.TextWriter textWriter = System.IO.File.CreateText(System.Windows.Forms.Application.StartupPath + &quot;\\IPAddress.txt&quot;);
            textWriter.WriteLine(txtportno.Text + &quot;;&quot; + txtipaddres.Text);
            textWriter.Close();
            DialogResult = System.Windows.Forms.DialogResult.OK;
            Close();
            }
        }
    catch (System.Exception e1)
        {
        }
    }

private void button2_Click(object sender, System.EventArgs e)
    {
    DialogResult = System.Windows.Forms.DialogResult.Cancel;
    Close();
    }

That's what Form.Close does: closes the current form.

BTW: Don't swallow your exceptions: they mean you don't find out why it failed (or that it failed in this case). Report 'em, log 'em, whatever. But empty catch blocks don't help anyone - least of all you.

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Member 238990017-Apr-16 0:46

17-Apr-16 0:46

Thanks OriginalGriff

Apologies, should have made my description clearer, the form never actually appears (or if it does then it quickly disappears), it is the only form currently and I am not entering / selecting anything (I don't get the chance).

Any thoughts appreciated.

Regards
Active

OriginalGriff17-Apr-16 0:50

17-Apr-16 0:50

So what code are you displaying it with?

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Member 238990017-Apr-16 0:55

17-Apr-16 0:55

I had expected that the following should make the form appear -

private void frmConfiguration_Load(object sender, System.EventArgs e)
        {
        }

private void InitializeComponent()
        {
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.btnok = new System.Windows.Forms.Button();

etc ...

Regards
Active

OriginalGriff17-Apr-16 1:06

17-Apr-16 1:06

No - what code makes the form display?
Are you creating it in Main (in process.cs)?
Or do you display it from an existing form?

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Member 238990017-Apr-16 1:16

17-Apr-16 1:16

Thanks, I was missing the .Run in main, thought it was something silly.

The form now appears but it is blank (no text, fields etc displaying), probably something else missing.

Regards
Active

OriginalGriff17-Apr-16 1:30

17-Apr-16 1:30

I don't see any form constructor in your code? So what is calling InitializeComponent - if you don't call that in a constructor, then there will be nothing to show!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Member 238990017-Apr-16 1:42

17-Apr-16 1:42

As you say the form constructor was missing (previously created by another form), silly me, again. Now working.

I appreciate your help OriginalGriff, thanks again.

Regards
Active

OriginalGriff17-Apr-16 1:44

17-Apr-16 1:44

You're welcome!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

OriginalGriff17-Apr-16 1:40

17-Apr-16 1:40

BTW: Are you creating all this by hand? If so, why?
You do realise that VS can create a "tidier" version of all that for you automatically?

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Philippe Mori18-Apr-16 12:34

Philippe Mori

18-Apr-16 12:34

Then where is the code to display the form? It won't appears magically... (except for the initial form which is initialized by the application).

Philippe Mori

using Enums as a design-strategy ?

ChizI19-Apr-16 7:25

ChizI

19-Apr-16 7:25

Please let me know the name of your software so I never use it. Anything with a namespace of TCPReader, but you don't know how to figure out why a form isn't appearing, is very scary.

--
Chizl

BillWoodruff16-Apr-16 21:59

BillWoodruff

16-Apr-16 21:59

The short version: "How do you use Enums in C# as: structural element ? design strategy ? Do you see any special "danger" in using elaborate Enum structures ?"

In the last few years, somehow I have moved to more, and more, frequent use of Enums in C# ... without having, at any point in time, made a conscious decision to do so (though reading code examples by people I consider .NET gurus here on CP, and on StkO, is probably an influence). Of course, I like the idea that Enums are memory-parsimonious, simple, relatively light-weight, and I like what using the [Flags] attribute lets you do. I really like the fact Enum values are compile-time constants that can be used in a 'Switch statement block.

I've come to believe that use of Enums + Interfaces (and generic Interfaces) are, as well, very powerful tools for application design (this may be so obvious to many of you reading this that you may wonder: "where has he been ?").

I've also come to think of Enums as a form of "self-documentation" in Code, as a design-organizing principle ... I am very curious how you react to that idea.

I have, lately, been reading the historical record of various advices on best practices with Enums given my MS over time.

And, I am aware of the argument/concept that creating an app with a large dependency on Enums may result in "future fragility:" an update changes one of the Enums ... adds a new value, makes some Enum value == 0 ... and code-breaks all over the place. I wonder if there's any qualitative difference ... vis a vis an app's future modifications ... between dependency-with-Enums and dependency because of reliance on Interfaces, or Class/Struct OOP design ?

I've recently been experimenting with Enums, doing things using "nested Enums:

[Description("The Play")]          // standard attribue: DescriptionAttribute
[Status("Tests Valid 03/23/2016")] // custom attribute: StatusAttribute
public enum ThePlay
{
   Act1 = 1, Act2 = 2, Act3 = 3
}

[Description("The Murder")]
[Status("Act1 changed 12/02/2015")]
public enum Act1
{
   Scene1Suspects = 1, Scene2TheDetectives = 2
}

[Description("The Suspects")]
[Status("Scene1Suspects added 12/02/2015")]
[Flags]
public enum Scene1Suspects
{
   None = 0x0,
   Butler = 0x2,
   LadyX = 0x4,
   LordX = 0x8,
   Gardener = 0x10  
}

And, I find it easy to parse these (using Reflection) and construct a UI (like a TreeView) at run-time.using the Enums' names, values, and the content of any Attributes; it's easy to detect if the Enum uses 'Flags, relatively easy to make (using a TreeView) a node structure that enforces multiple child node checkboxes to be checked ... and, by the same token, easy enough to create a node structure that allows only one child node CheckBox to be checked

Possible drawbacks to using Enums as more than "simple" design-elements ?

1. no generic constraints of Type 'Enum allowed in generic objects: Jon Skeet has a "work-around" for this (which I haven't tried): [^]

2. more work required to serialize an Enum so it retains "Label" content.

3. Enums are not as "Type safe;" they're just "dumb wrappers" over some block of allocated integral Types.

4. an example of arguments against using Enums is presented in this article which provides code for a Class based alternative: [^].

appreciate your response.

thanks, Bill

«The truth is a snare: you cannot have it, without being caught. You cannot have the truth in such a way that you catch it, but only in such a way that it catches you.» Soren Kierkegaard

Garth J Lancaster16-Apr-16 23:01

Garth J Lancaster

16-Apr-16 23:01

I'm not sure if it helps or hinders you Bill (it certainly doesnt answer your questions, maybe its background material), but there's also this article from SAK

Enumeration Types do not Enumerate! Working around .NET and Language Limitations[^]

BillWoodruff16-Apr-16 23:29

BillWoodruff

16-Apr-16 23:29

Thanks, Garth, I will take another look at Sergey's article.

I am looking for "opinions," here, not necessarily "answers" Smile | :)

cheers, Bill

«The truth is a snare: you cannot have it, without being caught. You cannot have the truth in such a way that you catch it, but only in such a way that it catches you.» Soren Kierkegaard

John Torjo18-Apr-16 1:37

John Torjo

18-Apr-16 1:37

A few notes on my opinions/usages on enums:

1. I quite love enums. Especially when you use them to specify an argument to a function

Like enforcing a constraint,

enum month { jan, feb, ... , dec };

2. I know there are pitfalls, but if you know them, enums are really powerful. They are self-documenting. Code looks much better at the point of call.

Just imagine:

var lines = x.Split( new[] {"\r\n"}, SplitOptions.RemoveEmptyEntries);

The latter argument could have been a boolean, but then the code would have been much harder to understand:

<br />
// what does "true" really mean?<br />
var lines = x.Split( new[] {"\r\n"}, true);

3. One of the possible problems when using enums is when you add a new value. In this case, you'll pretty much need to update all the code that used switch-es based on this enum. That's why I strive to have as few functions that require a switch based on all possible values.

4. About "future fragility": If other code depends on exact enum values, I usually put a comment on top of the enum

// Do not change the values. Other assemblies depend on this exact matching<br />
enum month { jan = 1, feb = 2, ... , dec = 12 };

5. "Nested" enums. I have used something more or less similar in my code, but never more than 2 levels deep. So far, I haven't encountered any pitfalls.

6. Took a look at the Class based alternative - clearly, there are some scenarios for it, but I think most of the time, it's overkill (my personal opinion, of course Wink | ;)

)

Best,
John

-- Log Wizard - a Log Viewer that is easy and fun to use!

BillWoodruff18-Apr-16 4:45

BillWoodruff

18-Apr-16 4:45

Thanks, John, for your comments !

I'm doing an interesting experiment right now, kind of "pushing the limits" of what one can do with Enums, using nesting, Attributes, etc. I may have gotten a little "carried away" with it, and will re-evaluate it after I restore my big-picture perspective ... look at what it would mean to use classes, and structs (with named constants, etc.) to replace the Enums, taking advantage of inheritance.

See what happens when you don't have to work for a living ? Smile | :)

cheers, Bill

«The truth is a snare: you cannot have it, without being caught. You cannot have the truth in such a way that you catch it, but only in such a way that it catches you.» Soren Kierkegaard