Cacher is the code snippet organizer for pro developers

ArrayList<PVector> history = new ArrayList<PVector>();

void setup() {
  size(400,400);
  for(int i = 0; i<2; i++) {
    PVector point = new PVector(mouseX,mouseY);
   history.add(point);
  }
}


void draw() {
 // background(255);
  fill(0);
  //ellipse(mouseX,mouseY,20,20);
  strokeWeight(2);
  float x = mouseX; // replace with portValues[0]
  float y = mouseY; // replace with portValues[1]
  PVector point = new PVector(x,y);
  
  history.add(point);
  PVector newPt = history.get(history.size()-1);
  PVector oldPt = history.get(history.size()-2);
  
  
  line(oldPt.x,oldPt.y,newPt.x,newPt.y);
  //line(pmouseX,pmouseY,mouseX,mouseY);
  
}