?
Solved

canvas repaint

Posted on 1999-01-21
1
Medium Priority
?
665 Views
Last Modified: 2011-09-20
I have an applet with a class "Square" that extends canvas.
Below is an example of my code :

private Square square;
private TextArea textarea;

public void init () {
     textarea = new TextArea();
     square = new Square();
}

.....   //other codes
.....

public void repaintingCanvas() {
        textarea.append ("testing");       //line 1
        square.repaint();                  //line 2  
        textarea.append ("after testing"); //line 3
        }    


How come I will be able to see the execution of line 1 and line 3 first before seeing the execution of line 2. I tried to "sleep" the applet after line 2, hoping to see the effect of square.repaint()incase it takes time to repaint, but it will still sleep then I can see the words "after testing" in textarea (execution of line 3) and only later will I see the effect of repaint() of the particular canvas.

 Why is this so, is it because I am not optimizing my codes properly or because all directions of applet will be executed first and execution of canvas is done later.

fyi....applet implements runnable

0
Comment
Question by:caphey
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 16

Accepted Solution

by:
heyhey_ earned 300 total points
ID: 1234475
painting is usually done in another Thread (probably the standard event Thread) so:

- when you call repaint() you just make request for repainting, which may be server some time later.
- when you call repaint from the code that is triggered from some  Event (for example actionPerformed() of a Button) you are working INSIDE the event Thread, so paining (and all other events propagation) will be BLOCKED until you quit the event handler method. sleep() won't help too.

it a standard practice to place all the 'heavy' code inside another Thread, so that you don't block the system event&paint Thread.

if you need more help, you'd better post a small example that reproduces yout problem.

best regards
  heyhey

0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

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

Java had always been an easily readable and understandable language.  Some relatively recent changes in the language seem to be changing this pretty fast, and anyone that had not seen any Java code for the last 5 years will possibly have issues unde…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The viewer will learn how to implement Singleton Design Pattern in Java.
How to fix incompatible JVM issue while installing Eclipse While installing Eclipse in windows, got one error like above and unable to proceed with the installation. This video describes how to successfully install Eclipse. How to solve incompa…
Suggested Courses

719 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