Java扫描程序问题（JFrame）
我试图用扫描仪来编辑我的塔防游戏的等级。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是零，等等）。我发现了错误，但如何修复它，我需要添加/更改什么来消除此错误Java扫描程序问题（JFrame）,java,image,file,jframe,java.util.scanner,Java,Image,File,Jframe,Java.util.scanner,我试图用扫描仪来编辑我的塔防游戏的等级。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是零，等等）。我发现了错误，但如何修复它，我需要添加/更改什么来消除此错误 java.lang.NullPointerException at Levels.loadLevels(Levels.java:11) at Window.define(Window.java:28) at Window.paintComponent(Window.java:44)
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一个快速而肮脏的解决方案是，测试Window.room是否不为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我已经写了很多作品，如果这样做的话
但是你需要了解“static”是什么，为什么以及如何使用它。初学者的一个常见错误是，插入“static”关键字只是为了让编译器保持沉默
调查初始化类及其属性的顺序
在块中，要访问窗口，必须有一个引用。该引用可以传递给块的ctor：
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）
“最让我沮丧的是没有错误”}catch（异常e）{}
将它（以及每一个类似的语句）更改为catch（异常e）{e.printStackTrace（）；}
（…或者保持在黑暗中）。你如何知道在吞下异常后没有错误：catch（异常e）{}
。显然，如果忽略任何可能引发的异常，您会得到没有错误的印象。但是这种印象很有可能不是真实的。“很抱歉写了这么长的文章”为了更快地获得更好的帮助，请发布一个。新的图像图标（“参考资料/tileset_ground.png”）
这提醒了我。在所有那些假定使用字符串来表示文件
路径的方法/构造函数中，它可能需要一个URL
。这些类型的“嵌入式资源”在运行时将无法作为文件
对象访问。int y=0；不能抛出NPE，也不能抛出y++。因此Window.room.block，or Window.room或Window为null。好吧，我知道只有Window.room.block为null，但我如何修复它？我想我需要在room.java中更改一些东西，但是什么？也许你可以将block=
的初始化放入room的ctor中？我想知道为什么每次调用“draw”时都需要创建一个新的块数组。但我不确定你不仅要重新创建块数组，还要重新创建内部的块。
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);
}
}
}
}
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);
}
}
}
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Scanner loadLevelsScanner = new Scanner (loadPath);
if ((Window.room != null) &&
(Window.room.block != null)) {
// ... block until catch block
}
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);
}
}
}
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);
}
}
}
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);
}
}
}
public void define () {
room = new Room (this);
levels = new Levels ();