change this
FloatList xx;
FloatList yy;
ArrayList<FloatList> old_x;
ArrayList<FloatList> old_y;
Particle(PVector l) {
float vector_scale = 0.05;//ector scaling factor, we want small steps
FloatList xx = new FloatList();
FloatList yy = new FloatList();
ArrayList<FloatList> old_x = new ArrayList<FloatList>();
ArrayList<FloatList> old_y = new ArrayList<FloatList>();
to this
FloatList xx;
FloatList yy;
ArrayList<FloatList> old_x;
ArrayList<FloatList> old_y;
Particle(PVector l) {
float vector_scale = 0.05;//ector scaling factor, we want small steps
xx = new FloatList();
yy = new FloatList();
old_x = new ArrayList<FloatList>();
old_y = new ArrayList<FloatList>();
also wouldn’t it be easier just to maintain an arraylist of PVectors instead of two seperate lists for each ordinate… just a thought.