首先,这个问题是关于 15-Puzzle 的。我正在尝试学习如何用 Java 语言对其进行编码。
我必须在我的大学学习关于 IDA* 算法的人工智能,并找到了 Brian Borowski 的这个链接:http: //brian-borowski.com/Software/Puzzle/这是一个很好的链接,但我有一个错误当我试图在我的 Eclipse 上手动构建它时。
有谁能够帮我?我收到一条错误消息:
Exception in thread "main" java.lang.NullPointerException
at Puzzle.setNumOfTiles(Puzzle.java:45)
at Puzzle.<init>(Puzzle.java:25)
at GUI.<init>(GUI.java:196)
at Application.<init>(Application.java:19)
at Application.main(Application.java:27)
我已经尝试追踪错误,谷歌搜索,但我仍然找不到解决方案。它说当某些变量具有空值时会发生 NullPointerException。有人可以在这里帮助我吗?
这是源代码
应用程序.java
public class Application {
/**
* Default constructor.
* Creates an instance of the gui.
*/
public Application() {
ApplicationStarter appStarter = null;
new GUI(appStarter); // Line 19
}
/**
* Main method.
* Creates an instance of the application.
*/
public static void main(final String[] args) {
new Application(); // Line 27
}
}
拼图.java
public Puzzle(final int numOfTiles) {
super();
setNumOfTiles(numOfTiles); // Line 25
setSize(panelWidth, panelHeight);
setDoubleBuffered(true);
}
public void setNumOfTiles(final int numOfTiles) {
this.numOfTiles = numOfTiles;
dimension = (int)Math.sqrt(numOfTiles);
imageArray = new Image[numOfTiles];
final String file = "images/" + (numOfTiles - 1) + "-puzzle/shrksign_";
imageArray[0] = null;
for (int i = 1; i < numOfTiles; ++i) {
final StringBuilder builder = new StringBuilder(file);
if (i <= 9) {
builder.append("0");
}
builder.append(Integer.toString(i));
builder.append(".gif");
imageArray[i] = ImagePanel.getImage(builder.toString());
}
imageWidth = imageArray[1].getWidth(null); // Line 45
imageHeight = imageArray[1].getHeight(null);
panelWidth = imageWidth * dimension;
panelHeight = imageHeight * dimension;
state = new byte[numOfTiles];
sleepMs = 500 / imageWidth;
animationDone = true;
resetOrder();
}
图形用户界面.java
...
this.puzzle = new Puzzle(PuzzleConfiguration.getNumOfTiles());
...