import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.IOException;
import java.util.Random;


class Moon {
    Image picture;
    int x;
    int y;

    Moon(int x, int y) throws IOException {
        this.x = x;
        this.y = y;
        picture = ImageIO.read(new java.io.File("moon.jpg"));
    }

    void shine(Graphics g) {
        g.drawImage(picture, x, y, 100, 100, null);
    }
}


class Ball {
    double x, y;
    double v;

    Ball(int x, int y) {
        this.x = x;
        this.y = y;
        v = 3;
    }

    void updateCoordinates(Rectangle rect) {
        final double g = 0.25;

        v += g;
        if (y + 45 > rect.height) {
            v *= -1;
        }

        y += v;
    }

    void draw(Graphics g) {
        g.setColor(new Color(200, 100, 100));
        g.fillOval((int) this.x, (int) this.y, 60, 60);
    }
}

class Panel extends JPanel {
    Ball[] balls;

    Moon moon;

    Panel() throws IOException {
        Timer nt = new Timer(10, e -> repaint());
        nt.start();
        Random random = new Random(42);

        moon = new Moon(50, 50);

        balls = new Ball[10];
        for (int i = 0; i < balls.length; ++i) {
            balls[i] = new Ball(random.nextInt(750), random.nextInt(400));
        }
    }


    public void paintComponent(Graphics g) {
        Rectangle canvas = g.getClipBounds();
        g.clearRect(0, 0, canvas.width, canvas.height);

        moon.shine(g);

        for (Ball ball : balls) {
            ball.updateCoordinates(canvas);
            ball.draw(g);
        }
    }
}

class Frame extends JFrame {
    Frame(int width, int height) throws IOException {
        Panel panel = new Panel();
        Container container = getContentPane();
        container.add(panel);
        setSize(width, height);
        setVisible(true);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        new Frame(800, 600);
    }
}