ArrayList throwing ConcurrentModificationException

Question

Hey everybody,
Im just goofing around with a little board game display class(my aim is to end up goofing around with A*, but thats still far in the future). Another thing I wanted to implement were little graphics FX. I use an ArrayList to display multiple FX:
class FX
    abstract void displayTo(Graphics g);
    abstract boolean finished() // has the effect finished its job?
ArrayList <FX> aL = new ArrayList<FX>();
for (FX f: aL)
    f.displayTo(getGraphics());
    if(f.finished()) FX.remove(f);
}Exact message:
Exception in thread "Thread-2" java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at gcds.TileMap.pumpFX(TileMap.java:44)
at gcds.TileMap.renderFrame(TileMap.java:39)
at pup.GCD.step(GCD.java:27)
at pup.GCD.frame(GCD.java:29)
at pup.GameCMP.run(GameCMP.java:25)
at java.lang.Thread.run(Thread.java:619)
I use a Thread(Runnable ) that paints a BufferedImage on a JPanel. The BufferedImage is being created by a method that calls the above piece of code.
Thanks for reading through this mess :)
Edit: I came up with a workaround - filling an ArrayList with Objects that need to be removed after the foreach loop - but I think thats not too elegant.
Edited by: anotherAikman on Jan 19, 2010 3:44 AM

Answer 1

anotherAikman wrote:
Thank you tschodt! Ill give it a try.
Edit:
Iterator<FX> it = FX.iterator();
while(it.hasNext())
FX m = it.next();
m.displayTo(getGraphics());
if(m.finished()) it.remove();
}seems to work good. Ill try some more things to ensure I understood the iterator logic.No "seems to" about it. That's exactly the fix!