916 Checkerboard V1 Codehs Fixed May 2026

CodeHS often uses a custom GraphicsProgram class. Here is the correct, working, fixed code for 9.1.6 Checkerboard (v1) in Java:

import acm.graphics.*;
import acm.program.*;
import java.awt.*;
public class Checkerboard extends GraphicsProgram  916 checkerboard v1 codehs fixed
private static final int SQUARE_SIZE = 50;
private static final int ROWS = 8;
private static final int COLUMNS = 8;
public void run() 
    for (int row = 0; row < ROWS; row++) 
        for (int col = 0; col < COLUMNS; col++) 
            int x = col * SQUARE_SIZE;
            int y = row * SQUARE_SIZE;
GRect square = new GRect(x, y, SQUARE_SIZE, SQUARE_SIZE);
            square.setFilled(true);
// Checkerboard logic: alternate color based on (row + col) % 2
            if ((row + col) % 2 == 0) 
                square.setColor(Color.RED);   // or Color.GRAY
             else 
                square.setColor(Color.BLACK);
add(square);

Create a 8x8 checkerboard using a loop. The checkerboard should have alternating black and white squares. CodeHS often uses a custom GraphicsProgram class

If you would like to create checkerboard you may use following code: Create a 8x8 checkerboard using a loop

import javax.swing.*;
import java.awt.*;
public class Checkerboard extends JPanel 
  public Checkerboard() 
    setPreferredSize(new Dimension(800, 800));
    setBackground(Color.WHITE);
@Override
  protected void paintComponent(Graphics g) 
    super.paintComponent(g);
    int rows = 8;
    int cols = 8;
    int squareSize = 100;
for (int row = 0; row < rows; row++) 
      for (int col = 0; col < cols; col++) 
        Color color = (row + col) % 2 == 0 ? Color.BLACK : Color.WHITE;
        g.setColor(color);
        g.fillRect(col * squareSize, row * squareSize, squareSize, squareSize);
public static void main(String[] args) 
    JFrame frame = new JFrame("Checkerboard");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new Checkerboard());
    frame.pack();
    frame.setVisible(true);

| Mistake | Consequence | Fix | |---------|------------|-----| | (col % 2 == 0) only | Stripes, not checkerboard | Use (row + col) % 2 | | Using setFillColor instead of setColor | Square remains unfilled | Use setColor OR both setFilled(true) and setFillColor | | Forgetting setFilled(true) | Transparent squares | Add square.setFilled(true); | | Incorrect loop bounds (e.g., row <= ROWS) | ArrayIndexOutOfBounds or extra row | Use < ROWS |