Drawing Multiplie Lines in a Buffered Image in Java

import java.awt.*;
import java.awt.image.*;
import javax.swing.*;

class GridLines {

    public static void main(String[] args) {

        Dimension imgDim = new Dimension(200,200);
        BufferedImage mazeImage = new BufferedImage(imgDim.width, imgDim.height, BufferedImage.TYPE_INT_RGB);


        Graphics2D g2d = mazeImage.createGraphics();
        g2d.setBackground(Color.WHITE);
        g2d.fillRect(0, 0, imgDim.width, imgDim.height);
        g2d.setColor(Color.BLACK);
        BasicStroke bs = new BasicStroke(2);
        g2d.setStroke(bs);
        // draw the black vertical and horizontal lines
        for(int i=0;i<21;i++){
            // unless divided by some factor, these lines were being
            // drawn outside the bound of the image..
            g2d.drawLine((imgDim.width+2)/20*i, 0, (imgDim.width+2)/20*i,imgDim.height-1);
            g2d.drawLine(0, (imgDim.height+2)/20*i, imgDim.width-1, (imgDim.height+2)/20*i);
        }

        ImageIcon ii = new ImageIcon(mazeImage);
        JOptionPane.showMessageDialog(null, ii);
    }
}