Circular hitbox jakelee

//-----------------
//
// Circular Hitbox
//
//-----------------

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class CircularHitbox extends Applet implements Runnable, KeyListener, MouseListener, MouseWheelListener
{
    Random gen = new Random();
    int a = gen.nextInt(256), b = gen.nextInt(256), d = gen.nextInt(256);
    int rad = 50;
    int xDim = 500, yDim = 500, time = 20;
    Color color = new Color(a, b, d);
    Circle c = new Circle(250, 250, rad);
    Color antiColor = new Color (256 - a, 256 - b, 256 - d);

    Font font = new Font("Arial", Font.BOLD, 20);

    int mouseX = 0, mouseY = 0;

    int distance = 5000;

    int xDiff = 1000;
    int yDiff = 1000;

    Image i;
    Graphics gg;

    public CircularHitbox()
    {

        setFocusable(true);
        setFocusTraversalKeysEnabled(false);
    }

    public void init()
    {
        this.setSize(xDim, yDim);
        setBackground(Color.black);
    }

    public void start()
    {
        Thread time = new Thread(this);
        time.start();

        addKeyListener (this);
        addMouseListener (this);
        addMouseWheelListener (this);
    }

    public void stop(){}

    public void keyPressed(KeyEvent e)
    {
        if (e.getKeyCode() == KeyEvent.VK_RIGHT)
        {

        }
    }

    public void mouseWheelMoved(MouseWheelEvent e)
    {
        int notches = e.getWheelRotation();
        if (notches < 0)
            rad += 5;
        else
            rad -= 5;
    }

    public void keyTyped(KeyEvent e)
    {

    }

    public void keyReleased(KeyEvent e)
    {

    }

    public void mouseEntered(MouseEvent e)
    {

    }

    public void mouseExited(MouseEvent e)
    {

    }

    public void mouseClicked(MouseEvent e)
    {

    }

    public void mouseReleased(MouseEvent e)
    {

    }

    public void mousePressed(MouseEvent e)
    {
        xDiff = e.getX() - c.x();
        yDiff = e.getY() - c.y();

        distance = (int) Math.sqrt((Math.pow(xDiff, 2) + Math.pow(yDiff, 2)));

        if (distance < c.radius)
        {
            a = gen.nextInt(256);
            b = gen.nextInt(256);
            d = gen.nextInt(256);
            color = new Color(a, b, d);
            antiColor = new Color( 256 - a, 256 - b, 256 - d);
            if (e.getButton() == e.BUTTON1)
            {
                rad += 5;
            }
            if (e.getButton() == e.BUTTON3)
            {
                if (rad > 6)
                {
                    rad -= 5;
                }
            }
        }
    }

    public void paint(Graphics g)
    {
        g.setColor(color);
        g.fillOval(c.x() - c.radius(), c.y() - c.radius(), c.diameter(), c.diameter());
        g.setFont(font);
        g.setColor(antiColor);
        g.drawString("Click Me!", xDim / 2 - 43, yDim / 2);
    }

    public void update(Graphics g){
        if(i == null){
            i = createImage(getSize().width, getSize().height);
            gg = i.getGraphics();}
        gg.setColor(getBackground());
        gg.fillRect(0,0, this.getSize().width, this.getSize().height);
        gg.setColor(getForeground());
        paint(gg);

        g.drawImage(i, 0, 0, this);

    }

    public void run()
    {
        Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
        while(true)
        {
            c.setRadius(rad);

            try
            {
                Thread.sleep(time);
            }
            catch(InterruptedException Ex){}
            repaint();
        }
    }
}