How to draw a grid line as a background on JPanel

Question

I have a problem. I used Gridbaglayout in my JFrame. One component is JPanel.

I wanted to draw a grid as a background for my JPanel. for example, in the program below, it should create 3 vertical and 3 horizontal lines, however it only shows two vertical and 2 horizontal lines. the last line was not shown.

Another problem was that the JPanel was larger than what I installed. I noticed this along the length of the line, which is shorter than the white background of JPanel.

  public class drawLayout extends JComponent 
    {

 public Dimension getPreferredSize() { 
  return new Dimension(600, 600); 
 }

 public int getY() { 
  return 0; 
 } 

 public int getX() { 
   return 0; 
    }

    @Override public void paintComponent(Graphics g)
    {
     g.setPaint(Color.GRAY);

            for (int i = 0; i <= getSize().width; i += 300) 
            {
               g2.drawLine(i, 0, i, getSize().height);
            }

            for (int i = 0; i <= getSize().height; i += 300) 
            {
               g2.drawLine(0,i, getSize().width, i);
            }
    } 
}

EDIT:

http://www.freeimagehosting.net/image.php?1af16edc28.jpg

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Answer 1

JPanel 600, 0 599. 600 .

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public class Jessy extends JFrame {

   private static final int DRAWING_SIZE = 600;
   private static final int SUBDIVISIONS = 2;
   private static final int SUBDIVISION_SIZE = DRAWING_SIZE / SUBDIVISIONS;

   public Jessy() {
      setSize(800, 800);
      setLayout(new GridBagLayout());
      GridBagConstraints gbc = new GridBagConstraints();
      gbc.weightx = 1.0;
      gbc.weighty = 1.0;
      gbc.gridx = 0;
      gbc.gridy = 0;
      JLabel drawingBoard = new JLabel("Drawing Board");
      gbc.anchor = GridBagConstraints.SOUTH;
      drawingBoard.setFont(new Font("Serif", Font.BOLD, 28));
      add(drawingBoard, gbc);
      JPanel panel = new JPanel() {
         @Override public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2 = (Graphics2D) g;
            g2.setPaint(Color.GRAY);
            for (int i = 1; i < SUBDIVISIONS; i++) {
               int x = i * SUBDIVISION_SIZE;
               g2.drawLine(x, 0, x, getSize().height);
            }
            for (int i = 1; i < SUBDIVISIONS; i++) {
               int y = i * SUBDIVISION_SIZE;
               g2.drawLine(0, y, getSize().width, y);
            }
         }          
      };
      panel.setPreferredSize(new Dimension(DRAWING_SIZE, DRAWING_SIZE));
      panel.setBackground(Color.WHITE);
      panel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
      gbc.gridy++;
      gbc.anchor = GridBagConstraints.CENTER;
      add(panel, gbc);
      JButton saveDrawing = new JButton("SAVE DRAWING");
      gbc.gridy++;
      gbc.anchor = GridBagConstraints.NORTH;
      add(saveDrawing, gbc);
   }
   public static void main(String[] args) {
      (new Jessy()).setVisible(true);
   }
}

:

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• , , kruler: 600 !:)

Answer 2

300. 600, for. 601 299. + 1 + 1 .