graphic - Drawing dashed line in java

Question

My problem is that I want to draw a dashed line in a panel, I'm able to do it but it draw my border in dashed line as well, which is oh my god!

Can someone please explain why? I'm using paintComponent to draw and draw straight to the panel

this is the code to draw dashed line:

public void drawDashedLine(Graphics g, int x1, int y1, int x2, int y2){
        Graphics2D g2d = (Graphics2D) g;
        //float dash[] = {10.0f};
        Stroke dashed = new BasicStroke(3, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL, 0, new float[]{9}, 0);
        g2d.setStroke(dashed);
        g2d.drawLine(x1, y1, x2, y2);
    }

Answer 1

You're modifying the Graphics instance passed into paintComponent(), which is also used to paint the borders.

Instead, make a copy of the Graphics instance and use that to do your drawing:

public void drawDashedLine(Graphics g, int x1, int y1, int x2, int y2){

  // Create a copy of the Graphics instance
  Graphics2D g2d = (Graphics2D) g.create();

  // Set the stroke of the copy, not the original 
  Stroke dashed = new BasicStroke(3, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL,
                                  0, new float[]{9}, 0);
  g2d.setStroke(dashed);

  // Draw to the copy
  g2d.drawLine(x1, y1, x2, y2);

  // Get rid of the copy
  g2d.dispose();
}