Lunar Lander

hello im making a lunar lander program but im having trouble with the accleration and when you click the left and right arrows the ball goes flying can anyone help fix my code

import java.awt.*;
import java.awt.event.*;

public class lunarlander extends java.applet.Applet implements MouseListener, KeyListener
{
        double x = 100, y = 40;
        double vx = 0.1, vy = 0.1;

        public lunarlander()
        {
            addMouseListener(this);
            addKeyListener(this);
        }
        public void paint(Graphics g)
        {
            vy = vy + 0.1;
            vx = vx + 0.001;
            vy = vy * 0.999;
            vx = vx * 0.999;
            if(y > 600 && vy > 0)
                vy = - vy;
            x = x + vx;
            y = y + vy;
            g.fillOval((int)x,(int)y,30,30);
            for(int i = 0; i < 100000; i ++)
            repaint();
            if(y < 100)
            g.drawString("Crash", 800, 800);
        }
        public void keyReleased(KeyEvent ke){}
        public void keyPressed(KeyEvent ke)
        {
            if(ke.getKeyCode() == KeyEvent.VK_UP)
                vy-=vy+2.0;
            else if(ke.getKeyCode() == KeyEvent.VK_DOWN)
                vy-=vy-4.0;
            else if(ke.getKeyCode() == KeyEvent.VK_LEFT)
                vx+=x-0.01;
            else if(ke.getKeyCode() == KeyEvent.VK_RIGHT)
                vx+=x-0.01;
        }
        public void keyTyped(KeyEvent ke){}
        public void mouseExited(MouseEvent me){}
        public void mouseEntered(MouseEvent me){}
        public void mouseClicked(MouseEvent me){}
        public void mouseReleased(MouseEvent me){}
        public void mousePressed(MouseEvent me){}
}