Re: Button.Text has no effect? - C# Discussion Boards

Button.Text has no effect?

3-May-07 4:54

bashiwala wrote:
But I dont know Java and I want to use C# to make a phone application.

Only if you can cram the .NET Framework into the phone. You can only use C# if your phone supports the .NET Compact Framework. If not, you can't use C#.

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

User 66583-May-07 4:37

User 6658

3-May-07 4:37

Hi
I'm struggling with a strange problem here, I can't set the text of a button in some circumstances.
Here's my code:

private void btnGo_Click(object sender, EventArgs e)
{
  try
  {
      btnGo.Text = "Processing..."; // this one doesn't work
      
      // blocking operation that might fail
   }
   catch (...)
   finally
   {
      btnGo.Text = "Start"; // this one works
   }
}

If I remove btnGo.Text = "Start", then the text "Processing" shows up once the long operation has finished.

/edit: I solved it by calling btnGo.Refresh() after btnGo.Text. But why is this necessary, will the button repaint itself only after another Paint-Event occured?

Does anyone know what might be causing this strange behaviour?

regards

modified 12-Sep-18 21:01pm.

Sandeep Akhare3-May-07 4:43

3-May-07 4:43

You need to use Asynchronous process using threads

Thanks and Regards
Sandeep

If you want something you never had,
do something you have never done!

Dave Kreskowiak3-May-07 4:53

3-May-07 4:53

Immediately after settings the button text, just call Application.DoEvents(), so your application gets and processes the message to repaint itself.

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

Sandeep Akhare3-May-07 5:08

3-May-07 5:08

There are many ways to do it if any one want to make user wait untill the process completes he can use asyncronous process as back ground thread .
There are n number of articles available on CP .
i know it is very tidious but more effective than Application.DoEvents()

Thanks and Regards
Sandeep

If you want something you never had,
do something you have never done!

Dave Kreskowiak3-May-07 5:35

3-May-07 5:35

There are also some people who are not ready to start throwing threads around. There are also situations where threading a process isn't acceptable, or would be too much work to keep the user from waiting for 1 or 2 seconds on a simpler process.

He really didn't give any kind of information about what this process was doing. So, to keep his code simple, DoEvents is a very easy fix to the immediate problem. If he wanted to move this process to a background thread, he can ask about that all he wants and we'll help with it.

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

User 66583-May-07 6:13

User 6658

3-May-07 6:13

I'm absolutely familiar with Threads and right after I posted this question I found the solution myself Smile | :)

I may switch my app to use threads in the future, but it's just a simple app for myself which querys a small database and displays some data, so button.Refresh() will do the job here.

regards

modified 12-Sep-18 21:01pm.

Dave Kreskowiak3-May-07 6:57

3-May-07 6:57

Greeeg wrote:
I'm absolutely familiar with Threads and right after I posted this question I found the solution myself

Great!

Greeeg wrote:
it's just a simple app for myself which querys a small database and displays some data,

Hence, the "simple" suggestion. Laugh | :laugh:

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

MoustafaS3-May-07 6:15

MoustafaS

3-May-07 6:15

May be the process is too fast, so the processing happens in less than second, and the finally line anyway will make it = "Start".

About : Islam

About : Me

Concept of Thread.BeginCriticalRegion()

Stefan Prodan3-May-07 12:05

Stefan Prodan

3-May-07 12:05

This is not a strange behavior, your should start a new thread to do the time consuming work and on the finish event of the tread set the btnGo.Text = "Start".

http://stefanprodan.wordpress.com

Sandeep Akhare3-May-07 4:28

3-May-07 4:28

HI All
I am confused while using Thread.BeginCriticalRegion(); in my application
what i am trying after compliting specific task by thread i have to abort same thread by calling abort method see the code

<br />
<br />
  private void button3_Click(object sender, EventArgs e)<br />
        {<br />
            ParameterizedThreadStart paramThreadDelagate = new ParameterizedThreadStart(WorkWithParameter);<br />
            Thread thread = new Thread(paramThreadDelagate);<br />
            thread.Start();<br />
            Thread.Sleep(1000);  <br />
            thread.Abort();<br />
            MessageBox.Show("Aborted");<br />
        }<br />
<br />
<br />
<br />
<br />
<br />
private void WorkWithParameter()<br />
 {<br />
       <br />
                Thread.BeginCriticalRegion();<br />
                MessageBox.Show("1");<br />
                MessageBox.Show("2");<br />
                MessageBox.Show("3");<br />
                MessageBox.Show("4");<br />
                MessageBox.Show("5");<br />
                Thread.EndCriticalRegion();<br />
 }<br />
<br />

The idea behind the critical region is to provide a region of code that must be executed as if it were a single statement. Any attempt to abort a thread while a critical region will have to wait until after the critical region is compplite .so the problem is i am getting message Aborted instead of executing whole WorkWithParameter method. Can any one help me out ?

Thanks and Regards
Sandeep

If you want something you never had,
do something you have never done!

Jimmanuel3-May-07 5:42

Jimmanuel

3-May-07 5:42

I'm not sure that BeginCriticalRegion does what you think it does. MSDN[^] says this about the function:

Notifies a host that execution is about to enter a region of code in which the effects of a thread abort or unhandled exception might jeopardize other tasks in the application domain.

It doesn't say anything about multiple lines of code being executed "as if it were a single statement", and doesn't suggest anywhere that it blocks Thread.Abort() from ending the Thread.

Sandeep Akhare3-May-07 19:55

3-May-07 19:55

Hi
But it says that Thread.Abort does not make any effect if the current context is in the critical region thats why Dot.NET 2.0 has introduced this and Thread.Suspend and Thread.Resume have been retired
Actually i m reading Microsoft press book name .NET FrameWork 2.0 Application Development Foundation by Tony Northup and many more in that book they mention " The idea behind the crical region is to provide a region of code that must be executed as if it were single statement . Any attempt to abort a thread while it is within a critical region will have to wait until after the critical region is complete ." PAge number 380 Chapter 7 lesson 1 .

Thanks and Regards
Sandeep

If you want something you never had,
do something you have never done!

Jimmanuel4-May-07 3:26

Jimmanuel

4-May-07 3:26

Hmm . . . from that text it does sound like BeginCriticalRegion is supposed to create a non-Abortable section of code, but your own test program is showing that it doesn't. When the author uses the phrase "The idea behind the critical region" it makes me wonder exactly what he means - does he mean that the code IS executed as one statement (and is therefore not abortable), or that idealistically .Net tries to make it appear to the CLR that the code being executed is one statement? The answer seems to be shown by your test program.

Check out this[^] post - it asks the same question that you have and Peter Ritchie [C# MVP] has done a good job of answering it.

pbraun3-May-07 8:34

pbraun

3-May-07 8:34

Look up "lock" or "Monitor" in your help.

Phil

Sandeep Akhare4-May-07 2:32

4-May-07 2:32

Lock and Monitor concept are for mulitythreading Synchronization concept
Which are not different what i asked i think

Thanks and Regards
Sandeep

If you want something you never had,
do something you have never done!