setting arraylist

Programming Questions

akeetekt

in Programming Questions • 2 years ago

Hi guys,

i'm working on a code but i've run into a problem when i try to run ArrayList.set

the code runs fine with arrayList.add but i'm unable to use this since i'm in void draw and it continuously adds.

I've added a a series of values in the void setup so that the set values don't start blank.

Many thanks,

akeetekt

for (int i=0;i<imgwidth-2;i+= stepSize) {
for (int j=0;j<imgheight;j+= stepSize) {
Vec3D origin = new Vec3D(i*gridSize, j*gridSize, 0);
Agent myAgent = new Agent(origin, color(0, 0, 255), att[i][j]);
int x= i/stepSize;
int y = j/stepSize;
muAttractor.set(x+(y*imgwidth/stepSize), myAgent);
// muAttractor.add(myAgent);
}
}

Replies(3)

amnon.owed

What is your question? What is your problem? What is the error you run into? We can't run your example.

In general it's no problem to set (replace) an ArrayList entry instead of adding it. See example below.

ArrayList <PVector> muAttractor = new ArrayList <PVector> ();
void setup() {
size(250, 250);
background(255);
for (int i=0; i<2; i++) {
muAttractor.add(new PVector(random(100), random(100)));
}
}
void draw() {
for (int i=0; i<2; i++) {
PVector v = new PVector(random(100), random(100));
muAttractor.set(i, v);
}
println(muAttractor);
}

The first value in set is the index. Your index value seems a bit strange. Perhaps that is causing problems.

akeetekt

Re: setting arraylist

2 years ago

thanks for the reply,

my problem lies in the conversion of a 1d arraylist into a 2d array list. I can solve the basic issue in this example

ArrayList<Float> myList;
//this code replaces 0 with 10
void setup() {
myList = new ArrayList<Float>();
for (int i=0;i<4;i++) {
myList.add(0.0);
}
}
void draw() {
for (int i=0;i<2;i++) {
for (int j=0;j<2;j++) {
myList.set(i+(j*2), 10.0);
println(myList);
}
}
}

but i'm running in to problems when i try:

for (int i=0;i<190;i+= 5) {
for (int j=0;j<150;j+= 5) {
int x= i/stepSize;
int y = j/stepSize;
muAttractor.set(x+(y*190/5), myAgent);
}
}

can you give me some advice please, or how i can mimic .set() but without using it

PhiLho

Re: setting arraylist

2 years ago

" i'm running in to problems"
We are not psychic, so you have to be more precise. What problems? Do you have error messages? What are they exactly? On which line?
Among other things, you have to ensure your x + y*190/5 falls within the bounds of the array list, check against muAttractor.size().

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