使用Java包时出错 [英] Error when using java packages

问题描述

我正在写一个游戏。它的目录树基本上是这样的：

I am writing a game. Its directory tree is basically like this:

ShootGame------>game----------------------->input--------------------------------->InputHandler.class
            |-->ShooterGame.class     |                                        |-->InputHandler.java
            |-->ShooterGame.java      |---->player-------------->Player.class                        
                                      |                      |-->Player.java
                                      |---->scenario---
                                                      |-->Block.class
                                                      |-->Block.java

我希望你理解我的图表，但重点是：游戏文件夹里面有3个文件夹，输入，‘玩家’，‘场景’。

I hope you understand my diagram, but the point is: the "game" folder has 3 folders inside it, "input","player","scenario".

在InputHandler.java中，我声明了包game.input 。

Inside "InputHandler.java", I have declared package game.input.

在Player.java中，我已声明包game.player 。

Inside "Player.java", I have declared package game.player.

在Block.java中，我声明了包game.scenario 。

And inside "Block.java", I have declared package game.scenario.

到目前为止，这么好。

但是，当在Player.java中，我执行导入game.input.InputHandler 时，它说包game.input不存在，即使我已经宣布game.input。

But when, in the Player.java, i do import game.input.InputHandler, it says "package game.input does not exist", even though I have already declared "game.input".

我在这里做错了什么？如果您需要文件中的代码，请发表评论。我不是在这里发布它们，因为我认为我遇到的主要问题是包和 import 逻辑。

What have I done wrong here? If you need the codes inside the files, please leave a comment. I am not posting them here because I think the main problem I have is the package and import logic.

谢谢。

编辑：

代码

Code

InputHandler.java

InputHandler.java

package game.input;

import java.awt.Component;
import java.awt.event.*;

public class InputHandler implements KeyListener{

    static boolean[] keys = new boolean[256];

    public InputHandler(Component c){
        c.addKeyListener(this);
    }

    public boolean isKeyDown(int keyCode){
        if (keyCode > 0 && keyCode < 256){
            return keys[keyCode];
        }

        return false;
    }

    public void keyPressed(KeyEvent e){
        if (e.getKeyCode() > 0 && e.getKeyCode() < 256){
            keys[e.getKeyCode()] = true;
        }
    }

    public void keyReleased(KeyEvent e){
        if (e.getKeyCode() > 0 && e.getKeyCode() < 256){
            keys[e.getKeyCode()] = false;
        }
    }

    public void keyTyped(KeyEvent e){}
}

Player.java

Player.java

package game.player;

import java.awt.*;
import javax.imageio.ImageIO;
import java.awt.Graphics;
import java.net.URL;
import java.awt.event.*;
import java.io.IOException;
import java.awt.image.BufferedImage;
import game.input.InputHandler;

public class Player{

    private BufferedImage sprite;
    public int x, y, width, height;
    private final double speed = 5.0d;

    public Player(int x, int y, int width, int height){
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;

        try{
            URL url = this.getClass().getResource("ship.png");
            sprite = ImageIO.read(url);
        } catch(IOException e){}
    }

    public void keyPlayer(double delta, InputHandler i){
        if(i.isKeyDown(KeyEvent.VK_D)){
            if(this.x>=1240) return;
            else this.x+=speed*delta;
        }

        if(i.isKeyDown(KeyEvent.VK_A)){
            if(this.x<=0) return;
            else this.x-=speed*delta;
        }

    }

    public void update(InputHandler inputP){
        keyPlayer(1.7, inputP);
    }

    public void Draw(Graphics a){
        a.drawImage(sprite,x,y,width,height,null);
    }

    public Rectangle getBounds(){
        return new Rectangle(x,y,width,height);
    }
}

Block.java

Block.java

package game.scenario;

import java.awt.*;
import javax.imageio.ImageIO;
import java.awt.Graphics;
import java.net.URL;
import java.awt.event.*;
import java.io.IOException;
import java.awt.image.BufferedImage;
import java.util.Timer;
import java.util.TimerTask;

public class Block{

    private Timer timer;
    private BufferedImage sprite;
    private final int t = 1;
    public int x, y, width, height;

    public Block(int x, int y, int width, int height){
        this.x=x;
        this.y=y;
        this.width=width;
        this.height=height;

        try{
            URL url = this.getClass().getResource("meteor.png");
            sprite = ImageIO.read(url);
        } catch(IOException e){}
    }

    public void Draw(Graphics g){
        g.drawImage(sprite,x,y,width,height,null);
    }

    public boolean destroy(Block b){
        if(b.y>=630){
            b = null;
            timer.cancel();
            timer.purge();
            return true;
        } else { return false; }
    }

    public void update(int sec){
        //if(getBounds().intersects(ShooterGame.ShooterGameClass.player.getBounds())){ System.out.println("Collision detected!"); }
        timer = new Timer();
        timer.schedule(new Move(), sec*1000);
        destroy(this);
    }

    class Move extends TimerTask{
        public void run(){
            int keeper = 5;
            if(keeper>0){
                y+=5;
            }
        }
    }

    public Rectangle getBounds(){
        return new Rectangle(x,y,width,height);
    }

}

主要类（游戏开始） ）
ShooterGame.java：

The main class(The game start) ShooterGame.java:

import java.awt.*;
import java.awt.event.*;
import javax.imageio.ImageIO;
import java.awt.Graphics;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.*;
import java.net.URL;
import java.io.IOException;
import java.awt.image.BufferedImage;
import java.awt.event.MouseEvent;
import game.input.InputHandler;
import game.player.Player;
import game.scenario.Block;

public class ShooterGame extends JFrame{
    static int playerX=500;
    static int playerY=520;

    InputHandler input = new InputHandler(this);
    public static Player player = new Player(playerX,playerY,50,50);
    Block meteor = new Block(100,100,30,30);

    public static void main(String[] args){
        ShooterGame game = new ShooterGame();
        game.run();
        System.exit(0);
    }

    static int windowWidth = 1300;
    static int windowHeight = 600;
    static int fps = 30;
    static BufferedImage backBuffer = new BufferedImage(windowWidth, windowHeight, BufferedImage.TYPE_INT_RGB);

    public void run(){
        boolean running = true;

        initialize();

        while(running){
            long time = System.currentTimeMillis();

            update();
            draw();

            time = (1000 / fps) - (System.currentTimeMillis() - time);

            if (time > 0) {
                try{
                    Thread.sleep(time);
                }
                catch(Exception e){};
            };
        }
    }

    public void initialize(){
        setTitle("--- Shooter Game ---");
        setSize(windowWidth, windowHeight);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }

    public void update(){
        player.update(input);
        meteor.update(0);
    }

    public void draw(){

        Graphics g = getGraphics();

        Graphics bbg = backBuffer.getGraphics();

        bbg.setColor(Color.BLACK);
        bbg.fillRect(0, 0, windowWidth, windowHeight);
        player.Draw(bbg);
        meteor.Draw(bbg);

        g.drawImage(backBuffer, 0, 0, this);
    }
}

命令：

编译Player，Block和InputHandler（javac 文件 .java）
然后用 _java ShooterGame

compiling Player, Block and InputHandler(javac file.java) then run the game with _java ShooterGame

推荐答案

您可能正在尝试从文件所在的目录中进行编译，这会错误地设置类路径。

You are probably trying to compile from inside the directory that the file is in, which is incorrectly setting the classpath.

cd game/player
javac Player.java

不要进入子包，而是显式设置类路径并从顶层编译。我假设 ShooterGame.java 在你的游戏文件夹中：

Instead of going into the subpackages, set the classpath explicitly and compile from the top level. I'm assuming that ShooterGame.java is in your game folder:

cd path/to/project/ShootGame
javac -cp . game/player/Player.java
... compile other classes
java -cp . game.ShooterGame

这篇关于使用Java包时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！