Java Applet ile yapılmış çizgi üzerinde ilerleyen top

import java.applet.Applet;
import java.awt.Graphics;
import java.util.logging.Level;
import java.util.logging.Logger;



public class cubuktangidencizgi extends Applet implements Runnable {
    int x=10,y=10,x1=180,y1=180;
    double egimy,egimx;
    public void init() {
        setSize(200, 200); 
        egimy=(y-y1)/(x1-x)+100;
        egimx=(x1-x)/(y-y1)+100;
        Thread t=new Thread(this);
        t.start();
    }
    public void paint(Graphics g) {
        g.drawLine(x,y, x1, y1);
        g.drawOval((int)egimx, (int) egimy, 20,20);
    }
    public void run() {
        int i=10;  int j=1;
        while(true){
            try {if (i<=170) {
                Thread.sleep(10);
                egimy=(y1-y)*i/(x1-x);
                egimx=(x1-x)*-egimy/(y-y1);
                repaint();i+=j;
                if (i==170) {
                    j*=-1;
                }if (i<10) {
                    j*=-1;
                }
                }
            } catch (InterruptedException e) {
            }
         
        }
    }

}

Ekran Görüntüsü;