How to check who submitting repaint() event in Swing?

Question

I have written a custom component that extends JPanel and overridden its paint() method. Now I can see that this method is called once per 10 milliseconds when the component is displaying. Nothing changes in the component but paint() is still called. I have several calls repaint() but none of them is called actually. How to know what is causing such frequent updates?

UPDATE! There was "bug" in my code. I was updating inner components form paint() method so it was the root cause of continuous repainting. But still, the question is not answered: how to understand what supplies events to the queue?

Please refer to https://stackoverflow.com/questions/34036540/overriding-the-paint-method — Miller Cy Chan, Oct 02 '18 at 08:23
I know about preferring paintComponent() over paint() but in my case, I need to paint over child components (selecting with mouse) — VDanyliuk, Oct 02 '18 at 08:49
For better help sooner, post a [MCVE] or [Short, Self Contained, Correct Example](http://www.sscce.org/). — Andrew Thompson, Oct 02 '18 at 11:46

camickr · Accepted Answer · 2018-10-02T16:28:30.453

how to understand what supplies events to the queue?

Whenever a property of a Swing component is changed the component will automatically invoke repaint() on itself. The paint request is passed to the RepaintManager.

The RepaintManager will then consolidate multiple repaint requests into a single painting of all components. The consolidation is done to make painting more efficient.

So the individual component that made the request is not available because in many cases multiple components will make the repaint request at the same time.

You can read Painting in AWT and Swing for a more detailed explanation.

score 0 · Answer 2 · answered Oct 02 '18 at 08:15

0

using debug make a break point in the paint() function and when it called you can watch the stack trace of the call back

answered Oct 02 '18 at 08:15

Hazem Ashraf

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It is called from AWTEventQueue thread. The question is who is submitting events to this queue. – VDanyliuk Oct 02 '18 at 08:18

How to check who submitting repaint() event in Swing?

2 Answers2