在1个JFrame中绘制多个对象

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

public class MyFrame extends JFrame {
    public MyFrame() {
        setTitle("绘制多个对象");
        setSize(500, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        
        // 绘制对象1
        g.drawRect(50, 50, 100, 100);
        
        // 绘制对象2
        g.drawOval(200, 200, 100, 100);
        
        // 绘制对象3
        g.drawString("Hello World!", 300, 300);
    }

    public static void main(String[] args) {
        MyFrame frame = new MyFrame();
    }
}