Java Snake Canvas

Program:

package snake;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.util.LinkedList;
public class SnakeCanvas extends Canvas implements Runnable
{
 private final int GRID_WIDTH = 30;
 private final int GRID_HEIGHT = 30;
 private final int BOX_WIDTH = 5;
 private final int BOX_HEIGHT = 5;
 private int direction = Direction.NO_DIRECTION;
 
 private LinkedList <Point> snake;
 private Point fruit;
 
 private Thread runThread;
 private Graphics globalGraphics;
 
 public void paint(Graphics g)
        {
  this.setPreferredSize(new Dimension(640,480));
  snake = new LinkedList<Point>();
  snake.add(new Point(3,1));
  snake.add(new Point(3,2));
  snake.add(new Point(3,3));
  fruit = new Point(0,0);
  
  globalGraphics = g.create();
  if (runThread == null)
                {
         runThread = new Thread();
         runThread.start();
         }
 }
 
 public void Draw(Graphics g)
        {
  DrawGrid(g);
  DrawSnake(g);
  DrawFruit(g);
 }
 public void Move()
        {
  
  Point head = snake.peekFirst();
  Point newPoint = head;   
  switch(direction)
               {
  case Direction.NORTH:
   newPoint = new Point(head.x, head.y - 1);
   break; 
  case Direction.SOUTH:
   newPoint = new Point(head.x, head.y + 1);
   break; 
  case Direction.WEST:
   newPoint = new Point(head.x - 1, head.y);
   break; 
  case Direction.EAST:
   newPoint = new Point(head.x + 1, head.y);
   break; 
  }
  
  snake.remove(snake.peekLast());
  
  if (newPoint.equals(fruit))
                {
   //has hit fruit
  }
  else
                if (newPoint.x < 0 || newPoint.x > GRID_WIDTH)
                {
   //went out of bounds
  }
  else 
                if (newPoint.y < 0 || newPoint.y > GRID_HEIGHT)
                {
   //went out of bounds
  }
  else 
               if (snake.contains(newPoint))
                 {
   //hit ourself
   }
  
  snake.push(newPoint);
  }
 
 public void DrawGrid(Graphics g)
        {
 
 //Draws the outside of the Rectangle
 g.drawRect(0,  0, GRID_HEIGHT * BOX_HEIGHT, GRID_WIDTH * BOX_WIDTH);
        //Draws the horizontal lines of the grid
 for (int x = BOX_WIDTH; x < GRID_WIDTH * BOX_WIDTH; x+= BOX_WIDTH)
        {
 g.drawLine(x, 0, x, BOX_HEIGHT * GRID_HEIGHT);}
        //Draws the vertical lines of the grid
 for (int y = BOX_HEIGHT; y < GRID_HEIGHT * BOX_HEIGHT; y+= BOX_HEIGHT)
        {
        g.drawLine(0, y, BOX_WIDTH * GRID_WIDTH, y);
        }
 }
 public void DrawSnake(Graphics g)
        {
  g.setColor(Color.BLUE); //Sets snake body to blue
 for (Point p : snake){g.fillRect(p.x * BOX_WIDTH, p.y * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT);
        } //Finds all snakes body parts filling in the grid at their points
 g.setColor(Color.BLACK); //Returns color back to normal
 }
        public void DrawFruit(Graphics g)
        {
        g.setColor(Color.RED); //Sets fruit color
 g.fillOval(fruit.x * BOX_WIDTH, fruit.y * BOX_HEIGHT, BOX_WIDTH , BOX_HEIGHT); //Draws circle within grid for fruit
 }
        @Override
 public void run() 
        {
        while(true)
        {
 Move();
 Draw(globalGraphics);
 try
        {
 Thread.currentThread();
 Thread.sleep(100);
 }
 catch (Exception e)
        {
 e.printStackTrace();
 }
 } 
 }
}