我应该用java中的队列创建一个蛇游戏。
我应该只使用下面的三个类，但是我不知道如何修改move（）函数来移动蛇，因为它是一个队列，我无法访问蛇的尾部。
我得出了以下结论：
蛇.java

import java.util.Random;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class Snake extends JFrame implements Runnable, KeyListener {

    int length=40, width = 30; 
    int time;
    int factor=10;
    Specialqueue q;      
    int direction = 6;          
    Thread t;
    int[][] food;             
    private boolean started;

    public Snake() {
        super("Snake");
        setSize(length*factor+30, width*factor+60);
        setVisible(true);
        addKeyListener(this);
        started = false;
        time = 0;
    }

    public void paint(Graphics g){
        if (g == null) return;    
        g.clearRect(0,0,getWidth(),getHeight());
        if (!gestartet){
            g.drawString("start the game by pressing 5",10,50);
            g.drawString("Controll the snake with W,A,S,D",10,80);
            return;
        }

        g.setColor(Color.blue);
        for (int k = 0; k < length; k++)
            for (int j = 0; j < breite; j++)
                if (food[k][j]==1)
                    g.fillOval(k*10,20+j*10,10,10);

    }  

    public void run() {
        time = 0;
        while (started){
            try {Thread.sleep(300);}
            catch (Exception e){};
            move();
            time++;
            Graphics g = this.getGraphics();
        }
    }

    public void stop() {
        started=false;
        t = null;
    }

    public void initFood() {

        food = new int[length][breite];
        for  (int k = 0; k < length; k++) {

         for (int j = 0; j < breite; j++) {
          if (Math.random() < 0.01) futter[k][j] = 1;
          else food[k][j] = 0;   
        }

        }
    }

    public void initSnake(){
        q = new Specialqueue();
        direction = 6;
        q.append(new Point(20,20));
        q.append(new Point(19,20));
        q.append(new Point(18,20));
        q.append(new Point(17,20));
        Graphics g = this.getGraphics();
        repaint();
        g.setColor(Color.red);
        g.fillOval(20*10,20+20*10,10,10);
        g.fillOval(19*10,20+20*10,10,10);
        g.fillOval(18*10,20+20*10,10,10);
        g.fillOval(17*10,20+20*10,10,10);
        g.setColor(Color.black); 
    }

    public void move()
    {
      Graphics g = this.getGraphics();
      Point p = (Point)q.tail();
      Point newPoint = null;
      int size = 4;

      if (direction == 6) {
         for(int i=0;i<3;i++) {
             q.remove();
         } 

         for(int q=0;q<3;q++) {
             newPoint = new Point(p.x+1, p.y);
         }
         if (newPoint.x >= length) {stoppe(); return;}
      }

      else if (direction == 4) {
         newPoint = new Point(p.x-1, p.y);
         if (newPoint.x < 0) {stoppe(); return;}
      }
      else if (direction == 8)
      {
         newPoint = new Point(p.x, p.y-1);
         if (newPoint.y < 0) {stoppe(); return;}
      }
      else if (direction == 2)
      {
         newPoint = new Point(p.x, p.y+1);
         if (newPoint.y >= width) {stoppe(); return;}
      }

      q.append(newPoint);
      p = (Point)q.tail();
      g.setColor(Color.red);
      g.fillOval(p.x*10,20+p.y*10,10,10);
      if(food[newPoint.x][newPoint.y] == 0){
        p = (Point)q.first();
        g.setColor(Color.white);
          g.fillOval(p.x*10,20+p.y*10,10,10);
        q.remove();
      }
      else {
          food[newPoint.x][newPoint.y]=0;

      }

    }

    public void keyPressed(KeyEvent ke)
    {
        char c = ke.getKeyChar();
        if (c=='5' && started) {started = false; t = null; repaint(); return; }
        if (c=='5' && !started){
            gestartet=true;
            initSnake();
            initFutter();
            t =  new Thread(this);
            try {Thread.sleep(150);} catch (Exception e){};
            t.start();
            return;
        }
        if ((c =='6' || c=='d') && direction != 4) direction = 6;
        else if ((c =='2' || c=='s') && direction != 8) direction = 2;
        else if ((c =='4' || c=='a') && direction != 6) direction = 4;
        else if ((c =='8' || c=='w') && direction != 2) direction = 8;
    }

}

特殊队列.java

public class Specialqueue <ContentType> {

        Queue<ContentType> s;

    public Specialqueue()
    {
        s = new Queue<ContentType>();
    }

    public ContentType tail(){
        if (s.isEmpty()) return null;
        return s.front();
    }

    public boolean isEmpty(){
        return s.isEmpty();
    }

    public void append(ContentType pContent) 
    { 
        s.enqueue(pContent);
    }

    public void remove() 
    {
    if(!s.isEmpty()) {
      s.dequeue();
}
    }

    public ContentType first(){
        if (this.isEmpty())
        {
            return null;
        }
        else{
            return s.front();
        }
    }

}

**Queue.java**

公共类队列{

protected class QueueNode {

    protected ContentType content = null;
    protected QueueNode nextNode = null;

    public QueueNode(ContentType pContent) {
        content = pContent;
        nextNode = null;
    }

    public void setNext(QueueNode pNext) {
        nextNode = pNext;
    }

    public QueueNode getNext() {
        return nextNode;
    }

    public ContentType getContent() {
        return content;
    }

}

protected QueueNode head;
protected QueueNode tail;

public Queue() {
    head = null;
    tail = null;
}

public boolean isEmpty() {
    return head == null;
}

public void enqueue(ContentType pContent) {
    if (pContent != null) {
        QueueNode newNode = new QueueNode(pContent);
        if (this.isEmpty()) {
            head = newNode;
            tail = newNode;
        } else {
            tail.setNext(newNode);
            tail = newNode;
        }
    }
}

public void dequeue() {
    if (!this.isEmpty()) {
        head = head.getNext();
        if (this.isEmpty()) {
            head = null;
            tail = null;
        }
    }
}

public ContentType front() {
    if (this.isEmpty()) {
        return null;
    } else {
        return head.getContent();
    }
}

}