我正在尝试使用扫描仪编辑塔防游戏的等级。但是它不会将级别（平铺图像）更新为自定义文件的级别（0是草1是石头-1是什么，等等）。我发现了错误，但我如何修复它，我需要添加/更改以摆脱这个？
java.lang.NullPointerException
at Levels.loadLevels(Levels.java:11)
at Window.define(Window.java:28)
at Window.paintComponent(Window.java:44)
第11行：for(int y=0;y<Window.room.block.length;y++) {
第28行：levels.loadLevels(new File("levels/level1.level"));
第44行：define();
这是扫描仪文件：
import java.io.*;
import java.util.*;
public class Levels {
public void loadLevels(File loadPath) {
try {
Scanner loadLevelsScanner = new Scanner(loadPath);
while(loadLevelsScanner.hasNext()) {
for(int y=0;y<Window.room.block.length;y++) {
for(int x=0;x<Window.room.block[0].length;x++) {
Window.room.block[y][x].groundID = loadLevelsScanner.nextInt();
}
}
for(int y=0;y<Window.room.block.length;y++) {
for(int x=0;x<Window.room.block[0].length;x++) {
Window.room.block[y][x].airID = loadLevelsScanner.nextInt();
}
}
}
loadLevelsScanner.close();
} catch(Exception e) {
}
}
}
这是窗口文件：
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.io.*;
public class Window extends JPanel implements Runnable {
public Thread thread = new Thread(this);
public static Image[] tileset_ground = new Image[100];
public static Image[] tileset_air = new Image[100];
public static int myWidth, myHeight;
public static boolean isFirst = true;
public static Room room;
public static Levels levels;
public Window() {
thread.start();
}
public void define() {
room = new Room();
levels = new Levels();
levels.loadLevels(new File("levels/level1.level"));
for(int i=0;i<tileset_ground.length; i++) {
tileset_ground[i] = new ImageIcon("resources/tileset_ground.png").getImage();
tileset_ground[i] = createImage(new FilteredImageSource(tileset_ground[i].getSource(), new CropImageFilter(0, 32 * i, 32, 32)));
}
for(int i=0;i<tileset_air.length; i++) {
tileset_air[i] = new ImageIcon("resources/tileset_air.png").getImage();
tileset_air[i] = createImage(new FilteredImageSource(tileset_air[i].getSource(), new CropImageFilter(0, 32 * i, 32, 32)));
}
}
public void paintComponent(Graphics g) {
if(isFirst) {
define();
isFirst = false;
}
g.clearRect(0, 0, getWidth(), getHeight());
room.draw(g);
}
public void run() {
while(true) {
if(!isFirst) {
room.physic();
}
repaint();
try {
Thread.sleep(1);
} catch(Exception e) {
}
}
}
}
这是房间档案：
import java.awt.*;
public class Room {
public int worldWidth = 40;
public int worldHeight = 20;
public int blockSize = 32;
public Block[][] block;
public Room () { }
public void define () { }
public void physic () { }
public void draw(Graphics g) {
block = new Block[worldHeight][worldWidth];
for(int y=0;y<block.length;y++) {
for(int x=0;x<block[0].length;x++) {
block[y][x] = new Block(x * blockSize, y * blockSize, blockSize, blockSize, Value.groundGrass, Value.airAir);
block[y][x].draw(g);
}
}
}
}
这是阻止文件：
import java.awt.*;
public class Block extends Rectangle {
public int groundID;
public int airID;
public Block(int x, int y, int width, int height, int groundID, int airID) {
setBounds(x, y, width, height);
this.groundID = groundID;
this.airID = airID;
}
public void draw(Graphics g) {
g.drawImage(Window.tileset_ground[groundID], x, y, width, height, null);
if(airID != Value.airAir) {
g.drawImage(Window.tileset_air[airID], x, y, width, height, null);
}
}
}
最后这是扫描仪应该读取的自定义文件：
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
答案 0 :(得分：1)
一个快速而肮脏的解决方案是，测试Window.room不为null，以及.block：
Scanner loadLevelsScanner = new Scanner (loadPath);
if ((Window.room != null) &&
(Window.room.block != null)) {
// ... block until catch block
}
一个简单的Testapp我写的作品到目前为止，如果这样做了。
但是你需要了解“静态”是什么，以及为什么以及如何使用它。一个常见的初学者错误是，为了使编译器保持沉默而使用“静态”关键字。
调查，按顺序初始化您的类及其属性。
在Block中，要访问Window，您必须有一个引用。该引用可以传递给Block的代码：
class Block extends Rectangle {
public int groundID;
public int airID;
Window window;
public Block (int x, int y, int width, int height, int groundID, int airID, Window window) {
setBounds (x, y, width, height);
this.groundID = groundID;
this.airID = airID;
this.window = window;
}
public void draw (Graphics g) {
g.drawImage (window.tileset_ground [groundID], x, y, width, height, null);
if (airID != Value.airAir) {
g.drawImage (window.tileset_air [airID], x, y, width, height, null);
}
}
}
谁创建了块？这是房间，所以房间本身需要了解窗户（只要你不从根本上改变你的设计）。
public Room (Window w) {
block = new Block [worldHeight] [worldWidth];
for (int y=0; y <block.length; y++) {
for (int x=0; x <block [0].length; x++) {
block [y] [x] = new Block (x * blockSize, y * blockSize, blockSize, blockSize, Value.groundGrass, Value.airAir, w);
}
}
}
创建，初始化块数组，并将块传递给Window参数。
在绘图中，您不会一遍又一遍地重新创建数组，也不会重新创建块，而只是重绘它们：
public void draw (Graphics g) {
for (int y=0; y <block.length; y++) {
for (int x=0; x <block [0].length; x++) {
block [y] [x].draw (g);
}
}
}
在Window中，您创建Room，并将窗口参考传递给它：
public void define () {
room = new Room (this);
levels = new Levels ();