JAVA的相关问题求解。（java Swing,常用组）

用JAVA绘制一个黑白棋牌（一个大正方形被分为若干小正方形，黑色小正方形和白色正方形交错）棋盘上下侧分别为文字北方参战者和南方参战者，左右两侧分别为文字西方观察团和东方观察团，

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

public class Frame extends JFrame {
    private static final int BOARD_SIZE = 8;
    private static final int SQUARE_SIZE = 50;

    public Frame() {
        setTitle("Black and White Chessboard");
        setSize(BOARD_SIZE * SQUARE_SIZE, BOARD_SIZE * SQUARE_SIZE);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setResizable(false);

        JPanel panel = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                drawChessboard(g);
                drawLabels(g);
            }
        };

        add(panel);
    }

    private void drawChessboard(Graphics g) {
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, BOARD_SIZE * SQUARE_SIZE, BOARD_SIZE * SQUARE_SIZE);

        for (int row = 0; row < BOARD_SIZE; row++) {
            for (int col = 0; col < BOARD_SIZE; col++) {
                if ((row + col) % 2 == 0) {
                    g.setColor(Color.BLACK);
                } else {
                    g.setColor(Color.WHITE);
                }
                g.fillRect(col * SQUARE_SIZE, row * SQUARE_SIZE, SQUARE_SIZE, SQUARE_SIZE);
            }
        }
    }

    private void drawLabels(Graphics g) {
        g.setColor(Color.BLACK);
        //g.setFont(new Font("Arial", Font.BOLD, 16));

        g.drawString("北方参战者", (BOARD_SIZE * SQUARE_SIZE - g.getFontMetrics().stringWidth("北方参战者")) / 2, 20);
        g.drawString("南方参战者", (BOARD_SIZE * SQUARE_SIZE - g.getFontMetrics().stringWidth("南方参战者")) / 2, BOARD_SIZE * SQUARE_SIZE - 10);

        Graphics2D g2d = (Graphics2D) g;
        g2d.rotate(Math.toRadians(90));
        g2d.drawString("西方观察团", (BOARD_SIZE * SQUARE_SIZE - g.getFontMetrics().stringWidth("西方观察团")) / 2, -10);
        g2d.drawString("东方观察团", (BOARD_SIZE * SQUARE_SIZE - g.getFontMetrics().stringWidth("东方观察团")) / 2, -(BOARD_SIZE * SQUARE_SIZE) + 20);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            Frame chessboard = new Frame();
            chessboard.setVisible(true);
        });
    }
}


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Chessboard extends JPanel {

    private static final int BOARD_SIZE = 8;
    private static final int SQUARE_SIZE = 60;

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        // 绘制棋盘背景
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, BOARD_SIZE * SQUARE_SIZE, BOARD_SIZE * SQUARE_SIZE);

        // 绘制棋盘格子
        boolean isBlackSquare = false;
        for (int row = 0; row < BOARD_SIZE; row++) {
            for (int col = 0; col < BOARD_SIZE; col++) {
                if (isBlackSquare) {
                    g.setColor(Color.BLACK);
                } else {
                    g.setColor(Color.WHITE);
                }
                g.fillRect(col * SQUARE_SIZE, row * SQUARE_SIZE, SQUARE_SIZE, SQUARE_SIZE);
                isBlackSquare = !isBlackSquare;
            }
            isBlackSquare = !isBlackSquare;
        }

        // 绘制文字
        g.setFont(new Font("Arial", Font.BOLD, 20));
        g.setColor(Color.BLACK);

        // 绘制北方参战者和南方参战者
        g.drawString("北方参战者", 0, (BOARD_SIZE * SQUARE_SIZE) + 30);
        g.drawString("南方参战者", 0, -10);

        // 绘制西方观察团和东方观察团
        g.drawString("西方观察团", -70, (BOARD_SIZE * SQUARE_SIZE) / 2);
        g.drawString("东方观察团", (BOARD_SIZE * SQUARE_SIZE) + 10, (BOARD_SIZE * SQUARE_SIZE) / 2);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Chessboard");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(BOARD_SIZE * SQUARE_SIZE, BOARD_SIZE * SQUARE_SIZE + 60);
        frame.add(new Chessboard());
        frame.setVisible(true);
    }
}