myApplet.java

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

class Ball {
    int x, y, radius, dx, dy;
    Color BallColor;

    public Ball(int x, int y, int radius, int dx, int dy, Color bColor) {
        this.x = x;
        this.y = y;
        this.radius = radius;
        this.dx = dx;
        this.dy = dy;
        BallColor = bColor;
    }
}

public class myApplet extends Applet implements Runnable {
    Ball redBall;

    public void init() {
        redBall = new Ball(150, 0, 20, 2, 5, Color.red);
        Thread t = new Thread(this);
        t.start();
    }

    public void paint(Graphics g) {
        g.setColor(redBall.BallColor);
        g.fillOval(redBall.x, redBall.y, redBall.radius, redBall.radius);
    }

    public void run() {
        try {
            Color c = redBall.BallColor;
            redBall.BallColor = new Color(c.getRed(), c.getBlue() + 20, c.getGreen());
            redBall.y = redBall.y + redBall.dy;
        } catch (Exception e) {
        }
        while (redBall.BallColor.getBlue() != 255) {
            try {
                displacementOperation(redBall);
                Thread.sleep(1000);
                repaint();
            } catch (Exception e) {
            }
        }
    }

    public void displacementOperation(Ball ball) {
        Color c = ball.BallColor;
        ball.BallColor = new Color(c.getRed(), c.getBlue() + 20, c.getGreen());
        ball.y = ball.y + ball.dy;
    }
}