Solved

how to force repaint()?

Posted on 1998-12-24
3
864 Views
Last Modified: 2008-03-17
Hi,

  My code has the following structure:

for(int i = 0; i < 10000; i++) {
  do some calculation;
  drawCanvas.repaint();
}

What I want is to do some calculation and plot the progress, and so on. But it seems that only after the loop is finished, the my "drawCanvas" is repainted(WM_PAINT message is blocked). May I know how to force painting? In MFC, we can use GetClientDC() to obtain a graphic device to draw on. Is there anything similar in Java? By the way, I need this to be done with JDK1.0.2 for maximum compatibility.
Thanks for your time.

wyldsj
0
Comment
Question by:wyldsj
  • 2
3 Comments
 
LVL 6

Accepted Solution

by:
gadio earned 20 total points
ID: 1230111
wyldsj, the repaint method notifys the awt thread that it needs to start a paint cycle. Now there are two options:
1. Your loop is done by the awt thread (for example inside one of the event handlers etc.). In that case, you have to change the design because the awt thread shouldn't be doing cpu intensive tasks.
2. You are doing the loop on a different thread, and your thread is very cpu intensive. There is a chance that the awt thread get very little reasources (cpu time), and what you can do is use the  command:  Thread.currentThread().yield();  After you are issueing the repaint(). This will cause the current thread to give up the cpu and give the awt thread the chance to do its work.

Hope this helps.
G
0
 

Author Comment

by:wyldsj
ID: 1230112
gadio: you are right. My loop is within an event handler. It actually occurs after a button is clicked. But I cannot figure out a different structure... Is there any suggestions from you?

wyldsj
0
 

Author Comment

by:wyldsj
ID: 1230113
Hi! I just figured it out myself and it worked now! Thanks for your help, gadio!

wyldsj
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Unable to open debugger port in Intellij idea 6 139
groupSumClump challenge 9 98
maven project error 5 44
GUI builder for Eclipse? 8 27
An old method to applying the Singleton pattern in your Java code is to check if a static instance, defined in the same class that needs to be instantiated once and only once, is null and then create a new instance; otherwise, the pre-existing insta…
This was posted to the Netbeans forum a Feb, 2010 and I also sent it to Verisign. Who didn't help much in my struggles to get my application signed. ------------------------- Start The idea here is to target your cell phones with the correct…
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
This video teaches viewers about errors in exception handling.

948 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now