我正在为我的编程类制作一个简单的Java applet游戏，并遇到了另一个问题。在游戏中，用户可以使用向上和向下箭头在y轴上的四个“通道”之间移动。空间将绘制子弹沿着x轴向下移动的图像，当子弹到达x轴上的某个点时移除子弹。现在我正在尝试这样做，以便屏幕上一次可以有多个子弹。
我一直在观看MyBringBack关于Java Applets游戏开发的YouTube系列，并找到了解决方案。我知道我应该让“播放器”成为一个单独的类中的对象，这样我就可以轻松地调用它的多个实例。问题是在YouTube系列中，他在使用图像时使用了Shapes。我明白如果我看过他这样做应该不会太难，但我很难确定在Object类中我需要哪些方法和变量。
我认为既然我必须为子弹做这件事，我也可以做其他对象（“玩家”，“牛”，“fastZombie”，“tankyZombie”，“normalZombie”和“bloodSplat”）。我通过尝试将处理“播放器”的所有内容放在一个单独的类中来开始，但是当我这样做时，ZombieAttackMain现在无法访问原始ZombieAttackMain类中使用的变量，并且新类无法访问ZombieAttackMain中的变量我将发布ZombieAttackMain的原始代码，如果有人有任何建议，我们将不胜感激。谢谢！
编辑：在ZombieAttackMain中，我无法再访问PLAYER_X_POSITION和playerYPosition。在我创建的Player类中，它无法访问POSITION_1_Y，POSITION_2_Y，POSITION_3_Y或POSITION_4_Y。
代码：
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class ZombieAttackMain extends Applet implements Runnable, KeyListener{
//all the comments with $ I removed and put in another class called Player and could not be accessed by ZombieAttackMain
//all the comments with # I copied and put in Player class
//all the comments with % could not be accessed by Player class
private Image background, normalZombie, fastZombie, tankyZombie,bullet, bloodSplat, cow1, cow2, cow3, cow4;
private Image player; //$
private Graphics bufferGraphics;
private Image offScreen;
private final int POSITION_1_Y = 100; //%
private final int POSITION_2_Y = 255; //%
private final int POSITION_3_Y = 400; //%
private final int POSITION_4_Y = 550; //%
private final int PLAYER_X_POSITION = 250; //$
private final int NORMAL_ZOMBIE_DX = -2;
private final int FAST_ZOMBIE_DX = -3;
private final int TANKY_ZOMBIE_DX = -1;
private final int BULLET_DX = 10;
private final int BULLET_STARTING_X_POSITION = 405;
private int zombieStartingXPosition = 1000;
private int playerYPosition = POSITION_3_Y; //$
private int zombieYPosition;
private int bulletXPosition, bulletYPosition;
private int bloodSplatX, bloodSplatY;
private boolean showBullet;
private boolean showFastZombie;
private boolean showTankyZombie;
private boolean showNormalZombie;
private boolean showCow;
public void init(){
setSize(1100, 700);
normalZombie = getImage(getCodeBase(), "NormalZombie.png");
tankyZombie = getImage(getCodeBase(), "TankyZombie.png");
fastZombie = getImage(getCodeBase(), "FastZombie.png");
player = getImage(getCodeBase(), "Player.png");
bullet = getImage(getCodeBase(), "Bullet.png");
bloodSplat = getImage(getCodeBase(), "BloodSplat.png");
background = getImage(getCodeBase(), "Background.jpg");
cow1 = getImage(getCodeBase(), "Cow.png");
cow2 = getImage(getCodeBase(),"Cow.png");
cow3 = getImage(getCodeBase(),"Cow.png");
cow4 = getImage(getCodeBase(),"Cow.png");
addKeyListener(this);
}
public void start() {
Thread thread = new Thread(this);
thread.start();
}
public void run() {
while(true){
repaint();
try {
Thread.sleep(17);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void update(Graphics g){
if(offScreen == null){
offScreen = createImage(this.getWidth(), this.getHeight());
bufferGraphics = offScreen.getGraphics();
}
bufferGraphics.setColor(getBackground());
bufferGraphics.fillRect(0,0,this.getWidth(),this.getHeight());
bufferGraphics.setColor(getForeground());
paint(bufferGraphics);
g.drawImage(offScreen,0,0,this);
}
public void paint(Graphics g){
g.drawImage(background,0,0,null);
g.drawImage(cow1,-15,115,null);
g.drawImage(cow2,-15,255,null);
g.drawImage(cow3,-15,400,null);
g.drawImage(cow4,-15,550,null);
g.drawImage(normalZombie,zombieStartingXPosition,100,null);
g.drawImage(tankyZombie,zombieStartingXPosition,400,null);
g.drawImage(fastZombie,zombieStartingXPosition,255,null);
g.drawImage(player,PLAYER_X_POSITION,playerYPosition, null); //$
g.drawImage(bloodSplat,bloodSplatX,bloodSplatY,null);
if(showBullet){
g.drawImage(bullet,bulletXPosition,bulletYPosition,this);
bulletXPosition += BULLET_DX;
if(bulletXPosition > 1100){
showBullet = false;
}
}
}
public void moveUp(Image player){ //$
if(playerYPosition == POSITION_2_Y){ //$
playerYPosition = POSITION_1_Y; //$
} //$
if(playerYPosition == POSITION_3_Y){ //$
playerYPosition = POSITION_2_Y; //$
} //$
if(playerYPosition == POSITION_4_Y){ //$
playerYPosition = POSITION_3_Y; //$
} //$
} //$
public void moveDown(Image player){ //$
if(playerYPosition == POSITION_3_Y){ //$
playerYPosition = POSITION_4_Y; //$
} //$
if(playerYPosition == POSITION_2_Y){ //$
playerYPosition = POSITION_3_Y; //$
} //$
if(playerYPosition == POSITION_1_Y){ //$
playerYPosition = POSITION_2_Y; //$
} //$
} //$
public void spawnBullet(){
if(showBullet){
return;
}
showBullet = true;
bulletXPosition = BULLET_STARTING_X_POSITION;
bulletYPosition = playerYPosition +83;
}
public void keyPressed(KeyEvent e) { //#
switch(e.getKeyCode()){ //#
case KeyEvent.VK_UP: //$
moveUp(player); //$
break; //$
case KeyEvent.VK_DOWN: //$
moveDown(player); //$
break; //$
case KeyEvent.VK_SPACE:
spawnBullet();
break;
}
}
public void keyReleased(KeyEvent e) { //#
} //#
public void keyTyped(KeyEvent e) { //#
} //#
public void stop() {
}
public void destroy() {
}
}
答案 0 :(得分：1)
你需要将所有这些类分开是正确的。无法访问变量的原因可能是因为您将它们设置为私有。因此，您应该使用“getters”访问它们。如果你不知道如何为你的课程制作getter，如果你正在使用eclipse，你可以去源 - ＆gt;生成getter和setter。因此，例如，如果您的Bullet类具有bulletXposition，那么在创建Bullet对象时从另一个类开始，假设您将其命名为“bullet”，并且可以调用bullet.getBulletXPosition等等。在我看来，你应首先阅读基础知识然后尝试制作游戏。
答案 1 :(得分：0)
对于您无法访问的变量，给出的信息量有限。我同意notArefill，他相信你不会以正确的方式访问变量。 示例（如果你有一个单独的Zombie类）：
public class Zombie{
private double x;
public void setX(double x){ // Setter
this.x = x;
}
public double getX(){ // Getter
return x;
}
}
然后当你需要从Zombies类引用X字段时，你会做这样的事情 在你的主要或你需要设置它/得到它的地方：
Zombie zombie = new Zombie(); // Create a new instance of your zombie or if available call existing zombi(say if stored in some sort of a collection)
zombie.setX(140.13); // To set the X coordinate
zombie.getX(); // To retrieve the X coordinate
希望有所帮助。