Processing 1.0 - Processing Discourse - Error message doesn't make any sense

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Index › Programming Questions & Help › Syntax Questions › Error message doesn't make any sense

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Error message doesn't make any sense (Read 1302 times)

Krux YaBB Newbies Offline Posts: 17	Error message doesn't make any sense Sep 3^rd, 2009, 3:57pm I get an error message "Cannot find a class or type named 'Manager'" but this doesn't make any sense, I have that class. here is the Project if you want to try it yourself: tetris.zip (9 KB)

blindfish

Re: Error message doesn't make any sense
Reply #1 - Sep 3^rd, 2009, 4:47pm

It does make sense - you've got some problems with braces in your Highscore tab. The Highscore class is closed too soon and an extra brace added after your Entry class. I guess the interpreter doesn't see your Manager class because the misplaced brace has somehow 'obscured' it...

Once you sort that it should work - it does for me, though I don't much like your choice of keyboard controls; but maybe I'm just being clumsy as it's rather late here. Time to sleep Shocked

Where is the what if the what is in why?

Krux

Re: Error message doesn't make any sense
Reply #2 - Sep 3^rd, 2009, 6:27pm

thanx. I think this time it was me who is the blind fish.
The controlls are intended to be used with one hand, so I can play while sitting on the other hand. The arrow keys are too fubar on my laptop.
The next thing I'll implement will be a feature that I can enter a name for the highscore.

Quote:

Time to sleep

very good idea.

Krux YaBB Newbies Offline Posts: 17	Re: Error message doesn't make any sense Reply #3 - Sep 6^th, 2009, 3:02pm I continue my quest in getting error messages without any sense how can arc2 be null here? circles.zip (3 KB) at first it runs smoothly, but after you move around a little bit you get the exception.

ben_hem Senior Member Offline Posts: 399 CA, US	Re: Error message doesn't make any sense Reply #4 - Sep 10^th, 2009, 10:40am Re: arc1 being null: your conditional actually guarantees that it will be null every time. In short, you have: if (arc1 != null){ // do this stuff if arc1 exists // arc1stuff } else if (arc2 != null){ // that is, if arc1 is null AND arc2 is not null arc2.draw(); arc1.draw(); // <-- whoops! } --Ben

Krux

Re: Error message doesn't make any sense
Reply #5 - Sep 10^th, 2009, 11:48am

ben_hem wrote on Sep 10^th, 2009, 10:40am:

Re: arc1 being null:
your conditional actually guarantees that it will be null every time. In short, you have:

if (arc1 != null){ // do this stuff if arc1 exists
// arc1stuff
}
else if (arc2 != null){ // that is, if arc1 is null AND arc2 is not null
arc2.draw();
arc1.draw(); // <-- whoops!
}

--Ben

that is not true
I have if (arc1 == null).

By the way the error doesn't come always. It comes in irregular timesteps.

I solved this problem with a try-catch-block and then I ignored the null Pointer exception. It runs smoothly, but it is not very clean. Any help is welcome.

PhiLho

Re: Error message doesn't make any sense
Reply #6 - Sep 10^th, 2009, 12:06pm

OK, I had time to test it. I can reproduce the problem.
My interpretation is that mouseMoved() is called asynchronously with regard to draw().
So my guess is that we have a myshape.append(mycircle) call between arc1.draw() and arc2.draw()... resulting in the NPE even though you correctly protected the accesses!

The fact I can reproduce that quite easily when mouse is going fast tends to corroborate the hypothesis.

I did the following change:
Code:

    synchronized (center)
    {
    if (verts == null){
	arc1 = null;
// [...]
	arc2 = new Arc(center,a,b);
    }
    }
// [...]
  void draw(){
    synchronized (center)
    {
    if (arc1 == null){
// [...]
	arc2.draw();
    }
    }
  }

ie. I added two synchronized blocks around the arcx accesses, and I could no longer reproduce the crash.

ben_hem Senior Member Offline Posts: 399 CA, US	Re: Error message doesn't make any sense Reply #7 - Sep 10^th, 2009, 4:35pm Quote: that is not true I have if (arc1 == null). My bad! glad you got it.

Krux YaBB Newbies Offline Posts: 17	Re: Error message doesn't make any sense Reply #8 - Sep 12^th, 2009, 10:35am thanks to all I will try it as soon as I can.

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