Create random circles in a grid

Processing Coding Questions
7

in case you have a list ( like 60 * 40 positions )
or just 10 songs
and you want play that 10 songs in a different sequence / like a music-player would do
you can use: a shuffled sequence:

int many = 10;
IntList seq = new IntList(many);
int current=0;

void preset() {
  for (int i = 0; i<many; i++) seq.append(i);
  seq.shuffle();
  for (int i = 0; i<many; i++) println(" i "+i+" "+seq.get(i));
}

void setup() {
  preset();
}

void draw() {
}

void keyPressed() {
  current++;
  if ( current >= many) { 
    current =0; 
    seq.shuffle();             //  optional reshuffle
  }
  println(" current "+current+" "+seq.get(current));
}

( sorry not looked your code, later … )