Using noLoop() and Loop()

jon.jekeli

in Integration and Hardware • 3 years ago

I have been creating a project in eclipse that is essentially a network map of connections between people (each person is a node, and it graphs connections between people by drawing edges between nodes). The network map has several different options as to which type of people it maps (family members, non-family members, or all people) in the sketch. I'm trying to make these options available off to the side of the GUI so the user can simply click on what people they would like to display and the sketch will modify itself in real time. I know that in order to do that, I have to temporarily halt the draw() method so I can modify variables before resuming the draw method. Therefore, I use noLoop(), then reset and modify the variables, then use loop(), as shown below, but I still get the ConcurrentModificationException coming out of my hashMap... any ideas as to why this still happens?

Relevant code:

if(e.getSource() == familyBtn {
embed.setVariables(bloomfieldUsed, false, true);
resetDisplay();
}
private void resetDisplay() { //embed is the Processing Applet contained in my GUI
embed.clear(); //simply calls noLoop, then resets all global variables to 0 or null
embed.loadData(); //modifies the data
embed.reset(); //calls loop()
}

Replies(3)

antiplast..

Re: Using noLoop() and Loop()

3 years ago

I think that your ConcurrentModificationException problem isn't related to the way you are using loop() or noLoop().

Maybe you are trying to remove objects from your hashmap while iterating over it? If this is the case, you could iterate backwards (for int i = map.size(); i > 0; i--) to avoid such problems.

Which line of your code is throwing this exception?

jon.jekeli

Re: Using noLoop() and Loop()

3 years ago

The draw() method throws it when it accessing the hash map (see highlighted line for the line that usually produces the error, although sometimes it is thrown from the edges iterator:

if (record) {
beginRecord(PDF, "output.pdf");
}
background(255);
textFont(font);
smooth();
Iterator iter = (Iterator)edges.iterator();
while (iter.hasNext()){
Edge e = (Edge)iter.next();
e.relax();
}
iter = (Iterator)nodes.iterator();
while (iter.hasNext()){
Node v = (Node)iter.next();
v.relax();
}
iter = (Iterator)nodes.iterator();
while (iter.hasNext()){
Node v = (Node)iter.next();
v.update();
}
iter = (Iterator)edges.iterator();
while (iter.hasNext()){
Edge e = (Edge)iter.next();
// e.eColor = noEdgeColor;
e.draw();
}
iter = (Iterator)nodes.iterator();
while (iter.hasNext()){
Node v = (Node)iter.next();
v.draw();
}
When noLoop() is called, does the draw() method stop immediately, or does it try to finish the loop it is currently on? Because if that is the case, then that is probably the problem... how can I make the Event Thread wait for the Animation Thread to finish if that is the case?
Thanks for your prompt reply

antiplast..

Re: Re: Using noLoop() and Loop()

3 years ago

noLoop() doesn't break the draw() method, it just prevents it from being executed again next time.

maybe you could use a simple variable to synchronize your threads. something like :

boolean busy = true; // set to true if draw() is looping
boolean event_request; // set to true when GUI input
void draw() {
// do your stuff here
if (event_request) {
noLoop();
busy = false;
}
}

Then your GUI should wait for "busy" to be set to false before changing the variables.

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