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

public class Pattern extends JComponent
{
   public static final int ROWS = 15;
   public static final int COLUMNS = 10;
   public static int GRID_SIZE = 20;

   private Color[][] colors; 

   public Pattern()
   {
      colors = new Color[ROWS][COLUMNS];
      makePattern();
   }

   public void makePattern()
   {
      for (int i = 0; i < ROWS; i++)
         for (int j = 0; j < COLUMNS; j++)
            colors[i][j] = Color.WHITE;

      // your code here
   }

   // Don't look at the code below...

   public void paintComponent(Graphics g)
   {
      Graphics2D g2 = (Graphics2D) g;
      for (int i = 0; i < ROWS; i++)
         for (int j = 0; j < COLUMNS; j++)
         {
            g2.setColor(colors[i][j]);
            g2.fill(new Rectangle(
                  j * GRID_SIZE,
                  i * GRID_SIZE, 
                  GRID_SIZE - 1, 
                  GRID_SIZE - 1));
         }
   }

   public Dimension getPreferredSize() 
   {
      return new Dimension(GRID_SIZE * COLUMNS,
         GRID_SIZE * ROWS);
   }
   
   public static void main(String[] args)
   {
      JFrame frame = new JFrame();
      frame.add(new Pattern());
      frame.pack();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}