protected void createGrid(){
  grid.clear();
  for (int r=0; r <= rows; ++r) {
    grid.add(new LineSegment(leftMargin,graphHeight - (bottomMargin + r * pixelsPerYTic),leftMargin + width,graphHeight - (bottomMargin + r * pixelsPerYTic)));
  }
  for (int c=0; c <= cols; ++c) {
    grid.add(new LineSegment(leftMargin + c * pixelsPerXTic,graphHeight - bottomMargin,leftMargin + c * pixelsPerXTic,graphHeight - (bottomMargin + height)));
  }
}

protected void createGrid ( ) { grid . clear ( ) ; for ( int r = 0 ; r <= rows ; ++ r ) { grid . add ( new LineSegment ( leftMargin , graphHeight - ( bottomMargin + r * pixelsPerYTic ) , leftMargin + width , graphHeight - ( bottomMargin + r * pixelsPerYTic ) ) ) ; } for ( int c = 0 ; c <= cols ; ++ c ) { grid . add ( new LineSegment ( leftMargin + c * pixelsPerXTic , graphHeight - bottomMargin , leftMargin + c * pixelsPerXTic , graphHeight - ( bottomMargin + height ) ) ) ; } }
create a grid of tick lines
