摇摆爪哇蛇游戏:看不见蛇的苹果
下面是我设计蛇游戏的视频: https://www.youtube.com/watch?v=91a7ceECNTc
我一步一步地跟踪它,但当我运行它时,屏幕上并没有显示蛇,只有苹果。我想我在执行public void paint(Graphics g);
时出了点问题。有人能帮我吗
这是我的主要课程代码
import javax.swing.JFrame;
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame ();
GamePanel panel = new GamePanel();
frame.add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Snake");
frame.pack();
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
}
这是Panel类:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JPanel;
public class GamePanel extends JPanel implements Runnable, KeyListener{
private static final long serialVersionUID = 1L;
public static final int WIDTH = 1000, HEIGHT = 1000; //Dimensions of the panel (Will be set by user input later)
private Thread thread;
private boolean running;
private boolean right = true, left = false, up = false, down = false;
private BodyPart b;
private ArrayList<BodyPart> snake;
private Apple apple;
private ArrayList<Apple> apples;
private Random r;
private int xCoor = 100, yCoor = 100, size = 10;
private int ticks = 0;
public GamePanel() {
setFocusable(true);
setPreferredSize(new Dimension(WIDTH, HEIGHT));
addKeyListener(this);
snake = new ArrayList<BodyPart>();
apples = new ArrayList<Apple>();
r = new Random();
start();
}
public void start() {
running = true;
thread = new Thread(this);
thread.start();
}
public void stop() {
running = false;
try {
thread.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void tick() {
if (snake.size() == 0) {
b = new BodyPart(xCoor, yCoor, 10);
snake.add(b);
}
ticks++;
if (ticks > 250000) {
if (right) {
xCoor++;
}
if (left) {
xCoor--;
}
if (up) {
yCoor--;
}
if (down) {
yCoor++;
}
ticks = 0;
b = new BodyPart(xCoor, yCoor, 10);
snake.add(b);
if (snake.size() > size) {
snake.remove(0);
}
}
if (apples.size() == 0) {
int xCoor = r.nextInt(99);
int yCoor = r.nextInt(99);
apple = new Apple(xCoor, yCoor, 10);
apples.add(apple);
}
}
public void paint(Graphics g) {
g.clearRect(0, 0, WIDTH, HEIGHT);
g.setColor(Color.BLACK);
g.fillRect(0, 0, WIDTH, HEIGHT);
for (int i = 0; i < WIDTH/10; i++) {
g.drawLine(i*10, 0, i*10, HEIGHT);
}
for (int i = 0; i < HEIGHT/10; i++) {
g.drawLine(0, i*10, HEIGHT, i*10);
}
for (int i = 0; i < snake.size(); i++) {
snake.get(i).draw(g);
}
for (int i = 0; i < apples.size(); i++) {
apples.get(i).draw(g);
}
}
@Override
public void run() {
while (running) {
tick();
repaint();
}
}
@Override
public void keyTyped(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_RIGHT && !left) {
right = true;
up = false;
down = false;
}
if (key == KeyEvent.VK_LEFT && !right) {
left = true;
up = false;
down = false;
}
if (key == KeyEvent.VK_UP && !down) {
up = true;
right = false;
left = false;
}
if (key == KeyEvent.VK_DOWN && !up) {
down = true;
right = false;
left = false;
}
}
@Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
}
蛇的身体部位类别:
import java.awt.Color;
import java.awt.Graphics;
public class BodyPart {
public int xCoor, yCoor, width, height;
public BodyPart(int xCoor, int yCoor, int tileSize) {
this.xCoor = xCoor;
this.yCoor = yCoor;
width = tileSize;
height = tileSize;
}
public void tick() {
}
public void draw(Graphics g) {
g.setColor(Color.YELLOW);
g.fillRect(xCoor * width, yCoor * height, width, height);
}
public int getCoorX() {
return xCoor;
}
public void setCoorX (int xCoor) {
this.xCoor = xCoor;
}
public int getCoorY() {
return yCoor;
}
public void setCoorY(int yCoor) {
this.yCoor = yCoor;
}
}
还有苹果的课程:
import java.awt.Color;
import java.awt.Graphics;
public class Apple {
public int xCoor, yCoor, width, height;
public Apple(int xCoor, int yCoor, int tileSize) {
this.xCoor = xCoor;
this.yCoor = yCoor;
width = tileSize;
height = tileSize;
}
public void tick() {
}
public void draw(Graphics g) {
g.setColor(Color.RED);
g.fillRect(xCoor * width, yCoor * height, width, height);
}
public int getxCoor() {
return xCoor;
}
public void setxCoor(int xCoor) {
this.xCoor = xCoor;
}
public int getyCoor() {
return yCoor;
}
public void setyCoor(int yCoor) {
this.yCoor = yCoor;
}
}
# 1 楼答案
好的,所以问题归结到一些基础数学
如果我们看一下
draw
的BodyPart
方法,你会发现好吧,很基本,但所有这些值都是真的设定的吗
如果我们看一下
tick
方法(创建BodyPart
),我们可以发现好的,那么
width
和height
是10
,但是xCoor
和yCoor
呢它们首先与类一起初始化为实例字段
所以,简单的一点数学告诉我们
BodyPart
的初始位置是100 * 10
,它等于1000x1000
如果我们也看看
及
我们可以看到
BodyPart
实际上最初是在屏幕上设置的所以,如果我们把初始位置改成更像
你会找到你失踪的蛇
一般建议
你应该避免覆盖
paint
。它在油漆链中的位置很高,很容易搞砸。取而代之的是paintComponent
(并确保您正在拨打super.paintComponent
)JPanel
然后将为您清除Graphics
上下文(使用组件的背景色)Swing不是线程安全的。您不应该从事件调度线程的上下文之外修改UI或UI依赖的任何状态
当前的“主”循环有引入脏更新的危险,这可能会在以后导致问题。见Concurrency in Swing。作为“一般”的首选项,您应该考虑使用Swing ^{} 。它不会阻止EDT,但其“滴答声”是在EDT内部生成的,因此从内部更新UI和/或其状态更安全
在执行操作时,你应该避免使用“幻数”
这里,
WIDTH
和HEIGHT
可能不代表组件的实际大小。而是使用JPanel#getWidth
和JPanel#getHeight
作为一般性建议,您应该避免使用
setPreferred/Minimum/MaximumSize
,其他人很容易将这些更改为您不想要的状态。取而代之的是重写getPreferred/Minimum/MaximumSize
,这样你就能保持控制