swing - Java: Drawing using Graphics outside the class which draws the main canvas

Question

I'm trying to develop a Tic Tac Toe game in Java using Graphics. My problem is: I don't want to add any other methods inside my Grid.class (which draws the lines 3x3), but i want to draw my X or O from a class called Game. My grid class looks like the following:

import java.awt.Graphics;
import javax.swing.JPanel;

public class Grid extends JPanel{

    private final int ITEM_WIDTH = 30;
    private final int ITEM_HEIGHT = 30;
    private final int OUTER_WIDTH = 90;
private final int OUTER_HEIGHT = 90;

public void paintComponent(Graphics g){
    super.paintComponent(g);
    drawOuter(g);
    drawGrid(g);
}

public void drawOuter(Graphics g){
    g.drawRect(0, 0, OUTER_WIDTH, OUTER_HEIGHT);
}

public void drawGrid(Graphics g){
    //Vertikális
    for(int i = ITEM_WIDTH; i < OUTER_WIDTH; i += ITEM_WIDTH){
        g.drawLine(i, 0, i, OUTER_HEIGHT);
    }
    //Horizontális
    for(int i = ITEM_HEIGHT; i < OUTER_HEIGHT; i += ITEM_HEIGHT){
        g.drawLine(0, i, OUTER_WIDTH, i);
    }
}

Thank you for your helps

Answer 1

My suggestion would be try to keep things as simple as possible.

• Create ImageIcons that hold your X and O images
• Have a GridLayout of JLabels placed in your JPanel above.
• Swapping the JLabel's ImageIcon when I wanted to display an X, an O, or a blank.

Proof of concept code. Clicking on the JLabels several times will show the icons. The code has no Tic-Tac-Toe logic though:

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;

import javax.swing.*;

@SuppressWarnings("serial")
public class XorOorBlank extends JPanel {
   private static final int IMG_WIDTH = 100;
   private static final Color BACKGROUND = Color.LIGHT_GRAY;
   private static final Color X_COLOR = Color.red;
   private static final Color O_COLOR = Color.blue;
   private static final Stroke X_STROKE = new BasicStroke(8f);
   private static final int GAP = 8;
   private static final int SIDE = 3;
   private Icon blankIcon = createBlankIcon();
   private Icon xIcon = createXIcon();
   private Icon oIcon = createOIcon();

   public XorOorBlank() {
      setBackground(BACKGROUND);
      setLayout(new GridLayout(SIDE, SIDE, GAP, GAP));

      MouseListener mouseListener = new MouseAdapter() {
         @Override
         public void mousePressed(MouseEvent e) {
            JLabel label = (JLabel) e.getSource();
            Icon icon = label.getIcon();
            if (icon == blankIcon) {
               icon = xIcon;
            } else if (icon == xIcon) {
               icon = oIcon;
            } else if (icon == oIcon) {
               icon = blankIcon;
            }
            label.setIcon(icon);
         }
      };
      for (int i = 0; i < SIDE; i++) {
         for (int j = 0; j < SIDE; j++) {
            JLabel label = new JLabel(blankIcon);
            label.addMouseListener(mouseListener);
            add(label);
         }
      }
   }

   private Icon createBlankIcon() {
      BufferedImage img = new BufferedImage(IMG_WIDTH, IMG_WIDTH,
            BufferedImage.TYPE_INT_ARGB);
      Graphics2D g2 = img.createGraphics();
      g2.setColor(Color.white);
      g2.fillRect(0, 0, IMG_WIDTH, IMG_WIDTH);
      g2.dispose();
      ImageIcon icon = new ImageIcon(img);
      return icon;
   }

   private Icon createXIcon() {
      BufferedImage img = new BufferedImage(IMG_WIDTH, IMG_WIDTH,
            BufferedImage.TYPE_INT_ARGB);
      Graphics2D g2 = img.createGraphics();
      g2.setColor(Color.white);
      g2.fillRect(0, 0, IMG_WIDTH, IMG_WIDTH);
      g2.setColor(X_COLOR);
      g2.setStroke(X_STROKE);
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
      int x1 = GAP;
      int y1 = x1;
      int x2 = IMG_WIDTH - GAP;
      int y2 = x2;
      g2.drawLine(x1, y1, x2, y2);
      g2.drawLine(x2, y1, x1, y2);
      g2.dispose();
      ImageIcon icon = new ImageIcon(img);
      return icon;
   }

   private Icon createOIcon() {
      BufferedImage img = new BufferedImage(IMG_WIDTH, IMG_WIDTH,
            BufferedImage.TYPE_INT_ARGB);
      Graphics2D g2 = img.createGraphics();
      g2.setColor(Color.white);
      g2.fillRect(0, 0, IMG_WIDTH, IMG_WIDTH);
      g2.setColor(O_COLOR);
      g2.setStroke(X_STROKE);
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
      int x1 = GAP;
      int y1 = x1;
      int x2 = IMG_WIDTH - 2 * GAP;
      int y2 = x2;
      g2.drawOval(x1, y1, x2, y2);
      g2.dispose();
      ImageIcon icon = new ImageIcon(img);
      return icon;
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("X or O");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new XorOorBlank());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

Note: not a paintComponent method to be found.

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