Calculating values for setPreferredsize

Question

I am trying to draw a simple graph. However, I can't seem to get the width size right for when I use setPreferredsize (I need to do this because I am using scroll panes). From my calculations the width is 1500, but it seems to be 3000. Can someone please explain why this is?
for (int i = 0; i < 1500; i++) {
                                 //data is array of integer data values
                    int ran = data;
                    //g2 is the graphics 2d instance
                    g2.drawRect( 2 * i, (100 - ran), 1, ran);

Answer 1

I am NOT sure what do you want to control. Your code does not show the real question. Generally, setPreferredSize(), setSize*() are difficult to control. Better way is to implement getPreferredSize(). Compute the size from the API implementation. Then it will generally work. In addition, you may have to use in combination with invalidate() and doLayout(). If you use Swing, controling sizes of components will make you crazy!