ImageIcon 方法無限循環

Question

我正在開發一個 Java 搖擺應用程序，我正在嘗試加載國際象棋棋子的圖像，並且一切都很好，直到突然出現錯誤：

Exception in thread "main" java.lang.StackOverflowError
    at java.base/java.lang.String.indexOf(String.java:1612)
    at java.base/java.lang.String.indexOf(String.java:1569)
    at java.base/java.net.URLStreamHandler.parseURL(URLStreamHandler.java:151)
    at java.base/sun.net.www.protocol.file.Handler.parseURL(Handler.java:67)
    at java.base/java.net.URL.<init>(URL.java:696)
    at java.base/java.net.URL.<init>(URL.java:563)
    at java.base/jdk.internal.loader.URLClassPath$FileLoader.getResource(URLClassPath.java:1222)
    at java.base/jdk.internal.loader.URLClassPath$FileLoader.findResource(URLClassPath.java:1211)
    at java.base/jdk.internal.loader.URLClassPath.findResource(URLClassPath.java:294)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findResourceOnClassPath(BuiltinClassLoader.java:499)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findResource(BuiltinClassLoader.java:323)
    at java.base/java.lang.ClassLoader.getResource(ClassLoader.java:1400)
    at java.base/java.lang.Class.getResource(Class.java:2741)
    at model.Board.getImageIcon(Board.java:246)
    at model.Board.setBoard(Board.java:49)
    at model.Board.<init>(Board.java:37)
    at model.Board.getBoardInstance(Board.java:28)
    at controler.FigureAction.<init>(FigureAction.java:15)
    at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)
at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)

並且來自at model.Board.setBoard(Board.java:49)部分在（僅該部分）之后被記錄了很多次。 在調試錯誤時，我看到它一遍又一遍地進入相同的方法，直到發生堆棧溢出錯誤。 我正在從本地地址檢索圖像。（以前都有效..）方法如下：

private ImageIcon getImageIcon(String path,String description) {
        URL imgURL = getClass().getResource(path);
        if (imgURL != null) {
            Image ii=new ImageIcon(imgURL, description).getImage().getScaledInstance(70, 70, Image.SCALE_SMOOTH);
            ImageIcon im=new ImageIcon(ii);
            return im;

        } 
        else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

它被稱為here

public void setBoard(Color c1,Color c2,Dimension dim) {

        for(int i=0;i<8;i++) {
            for(int j=0;j<8;j++) {
                Point point=new Point(i,j);
                if ((i+j)%2==0) {
                    if(i==0 && j==0) {
                        ***Figure f=new Figure (null,null,"white_rook",null,getImageIcon("/images/WhiteRook.png",null));***
                        fields[i][j]=new Field(c1,new Position(point.x,point.y),i*8+j,f);
                        f.field=fields[i][j];
                        f.pos=new Position(point.x,point.y);
                        fields[i][j].add(f);
                        figures[i][j]=f;
                    }

這是 setBoard 方法的一部分，它基本上將每個棋子放在場上。 圖類看起來像：

public class Figure extends JPanel {

    public Field field;
    public Color color;
    public String name;
    public Movement movement;
    public ImageIcon imageIcon;
    public Position pos;

    public Figure(Field field, Color color, String name, Movement movement, ImageIcon icon) {
        this.field = field;
        this.color = color;
        this.name = name;
        this.movement = movement;
        this.imageIcon = icon;
        this.setPreferredSize(new Dimension(70, 70));
        this.addMouseMotionListener(new FigureAction());
        this.addMouseListener(new FigureAction());
        this.setBackground(null);


    }
}

在這里，我正在從 png 圖像制作縮放的 imageIcon 並將其檢索回來。 如果有人能夠告訴我可能是什么問題，我將不勝感激。 我想我在這里遺漏了一些重要的東西，但目前不知道還能在哪里看.. 提前致謝。

Answer 1

首先getClass()實際上可能是一個子類，所以為了良好的順序：

    URL imgURL = Board.class.getResource(path);

然后，優化內存使用和速度。 我忽略這里的描述。

Map<String, ImageIcon> sharedIcons = new HashMap<>();

private ImageIcon getImageIcon(String path, String description) {
    ImageIcon icon = sharedIcons.get(path);
    if (icon == null) {
        URL imgURL = getClass().getResource(path);
        if (imgURL == null) {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
        icon = new ImageIcon(imgURL, description);
        Image ii = new ImageIcon(imgURL, description)
                .getImage().getScaledInstance(70, 70, Image.SCALE_SMOOTH);
        icon = new ImageIcon(ii);

        sharedIcons.put(path, icon);
    }
    return icon;
}

檢查沒有遞歸。 FigureAction調用setBoard左右。

Answer 2

根據您提供的堆棧跟蹤和代碼：

at model.Board.setBoard(Board.java:49)
at model.Board.<init>(Board.java:37)
at model.Board.getBoardInstance(Board.java:28)
at controler.FigureAction.<init>(FigureAction.java:15)
at model.Figure.<init>(Figure.java:30)

意思是：

1. 調用Figure構造函數。
2. 然后FigureAction構造函數。
3. 然后，在之后的某個時間點調用Board.setBoard 。
4. 但是Board.setBoard再次調用了您剛剛用 3 個星號突出顯示的行中的Figure構造函數...

為了解決這個問題，這取決於您要實現的目標。 這意味着我們需要更多代碼來查看（例如MRE ），如果您希望我們嘗試解決它。