如何编写代码以显示每个JPanel中的每个字母，以及如何旋转。(JFrame，NetBeans)

import javax.swing.JFrame;

public class MainFrame extends JFrame {
    public MainFrame() {
        setTitle("字母显示和旋转");
        setSize(800, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        
        // 创建并添加JPanel到窗口中
        add(new MyPanel());
    }

    public static void main(String[] args) {
        MainFrame frame = new MainFrame();
        frame.setVisible(true);
    }
}

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JPanel;
import javax.swing.Timer;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MyPanel extends JPanel implements ActionListener {
    private int angle = 0;
    private Timer timer;

    public MyPanel() {
        setBackground(Color.WHITE);
        timer = new Timer(10, this);
        timer.start();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        
        // 设置字体和大小
        Font font = new Font("Arial", Font.BOLD, 24);
        g2d.setFont(font);
        
        // 获取面板的宽度和高度
        int panelWidth = getWidth();
        int panelHeight = getHeight();
        
        // 计算字母的位置
        int x = panelWidth / 2 - 50;
        int y = panelHeight / 2;
        
        // 绘制字母
        String text = "Hello World";
        for (int i = 0; i < text.length(); i++) {
            char letter = text.charAt(i);
            g2d.drawString(String.valueOf(letter), x, y);
            x += 20;
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // 更新旋转角度
        angle += 1;
        if (angle >= 360) {
            angle = 0;
        }
        repaint();
    }
}