ControlP5 and "java.util.ConcurrentModificationException"

nootropic..

ControlP5 and "java.util.ConcurrentModificationException"

in Contributed Library Questions • 1 year ago

hi,

i'm experiencing a weird problem. i've tried to isolate the code that produce the error and i didn't managed to so i'm going to post quite a lot of code.

i think the problem is that i try to add controllersi (using the methods ControlP5.addToggle() in this example) during an event of the gui and this could bring to some errors in thread and some syncronizations fails..

when i move the slider it should be add a toggle. it is added but with this run time error (silently catched by controlP5):

java.util.ConcurrentModificationException

at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)

at java.util.AbstractList$Itr.next(AbstractList.java:343)

at controlP5.ControllerGroup.drawControllers(Unknown Source)

at controlP5.ControllerGroup.draw(Unknown Source)

at controlP5.ControlWindow.draw(Unknown Source)

at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:597)

at processing.core.PApplet$RegisteredMethods.handle(Unknown Source)

at processing.core.PApplet$RegisteredMethods.handle(Unknown Source)

at processing.core.PApplet.handleDraw(Unknown Source)

at processing.core.PApplet.run(Unknown Source)

at java.lang.Thread.run(Thread.java:662)

commenting lines 55-60 the problem disappear.

any ideas are appreciated!

here is the the code:

import controlP5.*;
final int MAX_QUAD = 5;
ControlP5 gui;
int num_quad = 0;
int earingLength = 300;
int k = 0;
ArrayList<Quad> quads = new ArrayList<Quad>();
void setup() {
size(800, 600);
smooth();
gui = new ControlP5(this);
gui.addSlider("setNumQuad")
.setCaptionLabel("num quad")
.setPosition(10, 10)
.setSize(200, 20)
.setRange(0, MAX_QUAD)
.setNumberOfTickMarks(MAX_QUAD+1)
;
}
void draw() {
background(100);
pushMatrix();
strokeWeight(3);
stroke(0);
noFill();
translate(width/2, height/2 - earingLength/2);
for (Quad q1 : quads) {
rect(-q1.edgeLength/2, q1.x,
q1.edgeLength, q1.edgeLength);
}
popMatrix();
}
void setNumQuad(int n) {
//println("setNumQuad: "+n);
if (n==num_quad) {
// end recursion
} else if (n>num_quad) {
//println("add new quad");
k += 51;
quads.add(new Quad(k, 20));
Toggle t = gui.addToggle(""+num_quad)
.setCaptionLabel("")
.setPosition(10+num_quad*(200/MAX_QUAD), 40)
.setSize(10,10)
.setId(0);
;
num_quad++;
setNumQuad(n);
} else if (n<num_quad) {
k -= 51;
//println("remove "+n);
quads.remove(quads.size()-1);
num_quad--;
gui.remove(""+num_quad);
setNumQuad(n);
}
//println(quads.size());
}
void controlEvent(ControlEvent theEvent) {
}
class Quad {
float edgeLength;
float x;
Quad(float x, float e) {
this.edgeLength = e;
this.x = x;
}
float getDiagonal() {
return edgeLength; // foo
}
float getLastPoint() {
return x+edgeLength;
}
}

Replies(3)

PhiLho

Re: ControlP5 and "java.util.ConcurrentModificationException"

1 year ago

Perhaps you can add the control from the start, but hide it, and make it appear when your condition is met.

nootropic..

Re: ControlP5 and "java.util.ConcurrentModificationException"

1 year ago

yeah it is exactly what i've done, i just was curious about this weird error and how can i avoid id

BinaryBra..

Re: ControlP5 and "java.util.ConcurrentModificationException"

1 year ago

I've had the same problem for a long time, I'm using the Layer library to create a Vjing software, so I have various "sketches", each with his own GUI, so in the setup phase I had to create each layer and his own controllers.
Iterating trough layers and calling each setup method I have encountered the same "ConcurrentModificationException".

I've found a temporary solution modifying controlP5 sources:

in ControlP5.java I've added those two methods to access the protected boolean "blockDraw" flag:

    public boolean isBlockDraw() {
        return blockDraw;
    }

    public void setBlockDraw(boolean blockDraw) {
        this.blockDraw = blockDraw;
    }

that is used in the draw() method of controlP5 itself to stop drawing the GUI.

    /**
    * call draw() from your program when autoDraw is disabled.
    *
    * @exclude
    */
    @ControlP5.Invisible
    public void draw() {
        if (blockDraw == false) {
            controlWindow.draw();
        }
    }

Now, in my code, I call:

controlP5.setBlockDraw(true);
...
// layers controllers creation
...
controlP5.setBlockDraw(false);

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