马士兵老师的贪吃蛇代码按了键盘没反应

ruo_qi 2017-09-01 09:07:44

在看马士兵的贪吃蛇视频，跟着视频写了一部分代码，目前可以实现只有一节的蛇移动起来，应该是可以改变方向的，但我的却只会沿着初始化的方向一直走，按方向键没反应，请问问题出在哪
Yard.java

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class Yard extends Frame {
public static final int ROWS=30;
public static final int COLS=30;
public static final int BLOCK_SIZE=20;
snake s=new snake();
public void lauch(){
this.setSize(ROWS*BLOCK_SIZE,COLS*BLOCK_SIZE);
this.setVisible(true);
this.setResizable(false);
this.addKeyListener(new KeyMonitor());
new Thread(new PaintThread()).start();
}
public void paint(Graphics g){
Color c=g.getColor();
g.setColor(Color.black);
for(int i=1;i<ROWS;i++)
{
g.drawLine(0,BLOCK_SIZE*i,BLOCK_SIZE*COLS,BLOCK_SIZE*i);
g.drawLine(BLOCK_SIZE*i,0,BLOCK_SIZE*i,BLOCK_SIZE*ROWS);
}
g.setColor(c);
s.draw(g);
}

public static void main(String[]args){
new Yard().lauch();
}
private class PaintThread implements Runnable{
public void run(){
while(true)
{
repaint();
try{
Thread.sleep(500);
}catch(InterruptedException e){
e.printStackTrace();
}
}
}
}
private class KeyMonitor extends KeyAdapter{
public void keyPresses(KeyEvent e){
s.keyPressed(e);
}

}
}

snake.java

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.*;

public class snake {
Node head=null;
Node tail=null;
int size=0;
private Node n=new Node(15,15,Dir.L);
public snake()
{
head=n;
tail=n;
size=1;
}
public void draw(Graphics g){
if(size<=0)return;
move();
for(Node n=head;n!=null;n=n.next)
{
n.draw(g);
}
}
private void move(){
addToHead();
deleteFromTail();
}
private void deleteFromTail(){
if(size==0)return;
tail=tail.prev;
tail.next=null;
}
public void addToTail(){
Node node=null;
switch(tail.dir){
case L:
node=new Node(tail.row,tail.col+1,tail.dir);
break;
case U:
node=new Node(tail.row+1,tail.col,tail.dir);
break;
case R:
node=new Node(tail.row,tail.col-1,tail.dir);
break;
case D:
node=new Node(tail.row-1,tail.col,tail.dir);
break;
}
tail.next=node;
node.prev=tail;
tail=node;
size++;
}
public void addToHead(){
Node node=null;
switch(head.dir){
case L:
node=new Node(head.row,head.col-1,head.dir);
break;
case U:
node=new Node(head.row-1,head.col,head.dir);
break;
case R:
node=new Node(head.row,head.col+1,head.dir);
break;
case D:
node=new Node(head.row+1,head.col,head.dir);
break;
}
node.next=head;
head.prev=node;
head=node;
size++;
}
class Node{
int col;
int row;
int w=Yard.BLOCK_SIZE;
int h=Yard.BLOCK_SIZE;
Dir dir=Dir.L;
Node next=null;
Node prev=null;
Node(int row,int col,Dir dir){
this.row=row;
this.col=col;
this.dir=dir;
}
void draw(Graphics g)
{
Color c=g.getColor();
g.setColor(Color.green);
g.fillRect(col*Yard.BLOCK_SIZE,row*Yard.BLOCK_SIZE,w,h);
}
}

public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
switch(key) {
case KeyEvent.VK_LEFT :
head.dir = Dir.L;
break;
case KeyEvent.VK_UP :
head.dir = Dir.U;
break;
case KeyEvent.VK_RIGHT :
head.dir = Dir.R;
break;
case KeyEvent.VK_DOWN :
head.dir = Dir.D;
break;
}
}
}

Dir.java
public enum Dir {
L,U,R,D
}

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