Strange error in a for loop...

Programming Questions

nbuechi

Strange error in a for loop...

in Programming Questions • 3 years ago

Hi,

I have a nice little server app running. But from time to time, it crashes, for no visible reason.

here is the error Processing tells me (or console when I exported the app:

Exception in thread "Animation Thread" java.lang.ArrayIndexOutOfBoundsException:1

at server_app.writeToArray(server_app.java:108)

at server_app.draw(server_app.java:97)

at processing.core.PApplet.handleDraw(PApplet.java:1606)

at processing.core.PApplet.run(PApplet.java:1503)

at java.lang.Thread.run(Thread.java:637

Ok, here is my line 108, which looks like it makes problems:

for(int j = 0; j <signals; j++) {

setDmxChannel(3,200);

setDmxChannel(1,pos_arr);

}

(first line is 108)

So, anyone has an Idea what is happening, or how I could prevent that? Or someone can write me an AppleScript, that if this error is happening, it restarts the computer?

Thanks for you help!

Greetings

Nicolas

Replies(4)

blindfish

Re: Strange error in a for loop...

3 years ago

It would probably help if you posted a bit more code... e.g. what does your server app communicate with? What is the variable 'signals' and how is it populated? Do you ensure you're getting clean data through?

kooogy

Re: Strange error in a for loop...

3 years ago

line 108 in your pde file is not line 108 in the java file so it's probably not that line. export it as an application and look at the generated .java file.

it, as the error suggests, is probably because you're accessing an element beyond the end of an array somewhere.

yes, we need more code.

nbuechi

Re: Strange error in a for loop...

3 years ago

Hi,

thank you,

the tip, that the java code line isnt the p55 code line was a good help. so I can now really see, in which area the error is:

void writeToArray(String data) {

data = trim(data);

String[] netInput = new String[5];

netInput[0]="a";

netInput[1]="a";

netInput[2]="a";

netInput[3]="a";

netInput[4]="a";

netInput = split(data, ",");

pos_arr = int(netInput[0]);

rohr_value = int(netInput[1]); // THIS LINE KICKS OUT THE ERROR!!!!!!!

if(pos_arr >0 && pos_arr<100) {

fernrohre[pos_arr] = rohr_value; println("pos arr length: " + fernrohre[pos_arr]);

println("pos arr: " + pos_arr);

}

So, looking at the console, the error is generated by this line:

rohr_value = int(netInput[1]);

Thats why I tried to fill up the array with 5 items, so it has in all cases enough indexes.

I really thank you for your help!

blindfish

Re: Strange error in a for loop...

3 years ago

Basically, you need to check the length of netInput before trying to access an element of the array. split() replaces the existing array; so trying to pre-populate it won't work:

void setup() {
String[] netInput = new String[5];
netInput[0]="a";
netInput[1]="a";
netInput[2]="a";
netInput[3]="a";
netInput[4]="a";
String foo = "a,b,c";
println("Before split(). Length: " + netInput.length);
println(netInput);
netInput = split(foo,",");
println("After split(). Length: " + netInput.length);
println(netInput);
}

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