java.lang.StackOverflowError 关于在 JPanel 中实现 Runnable - Java Swing

Question

我有一个 JPanel 实现了 Runnable 接口和 overrides run() 方法。在我的 JPanel 的构造函数中，我初始化了一个 private class(JPanel) Thread 的实例，它以 new MyPanel 作为参数。在这条线上，我得到一个 Exception in thread "main" java.lang.WhosebugError.

之后的错误：

    at java.awt.Component.setForeground(Unknown Source)
    at javax.swing.JComponent.setForeground(Unknown Source)
    at javax.swing.LookAndFeel.installColors(Unknown Source)
    at javax.swing.LookAndFeel.installColorsAndFont(Unknown Source)
    at javax.swing.plaf.basic.BasicPanelUI.installDefaults(Unknown Source)
    at javax.swing.plaf.basic.BasicPanelUI.installUI(Unknown Source)
    at javax.swing.JComponent.setUI(Unknown Source)
    at javax.swing.JPanel.setUI(Unknown Source)
    at javax.swing.JPanel.updateUI(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)

然后:

    at MyPanel.<init>(MyPanel.java:39)
    at MyPanel.<init>(MyPanel.java:45)

第 39 行是我的 JPanel 构造函数，第 45 行是 class Thread 的初始化代码，即 this.generateBallsThread = new Thread(new MyPanel());

这里只放了与问题相关的代码。

MyPanel.java:

public class MyPanel extends JPanel implements KeyListener,Runnable
{
    private static final long serialVersionUID = 1L;

    private static final Color BACKGROUND_COLOR = Color.WHITE; 
    private static final Color NPC_BALLS_COLOR = Color.RED;

    // The player is an oval
    private int playerRadius = 25;
    private int playerX;
    private int playerY;

    // True - first player position, false - otherwise
    private boolean playerPosition = true;

    // Array of all the balls threads
    private ArrayList<BallThread> balls = new ArrayList<BallThread>();

    private Thread generateBallsThread;

    public MyPanel()
    {
        this.setBackground(MyPanel.BACKGROUND_COLOR);
        this.setFocusable(true);
        this.addKeyListener(this);

        this.generateBallsThread = new Thread(new MyPanel()); // WhosebugError
        generateBallsThread.start();
    }
}

我很困惑。这就是您使用 Runnable 界面的方式，所以 java 想要我做什么？

Answer 1

将 new MyPanel() 替换为 this。这将停止导致堆栈溢出的无限递归调用

Answer 2

为什么会出现 SO 异常？ MyPanel class 的构造函数会创建另一个 MyPanel。这会导致 class 继续创建，直到超出堆栈边界，从而导致堆栈溢出。

Answer 3

由于该行，您的代码将进入无限循环 this.generateBallsThread = 新线程（新我的面板（））；，因为您正在其构造函数中创建 class MyPanel 的对象，它将再次调用相同的构造函数。

java.lang.StackOverflowError 关于在 JPanel 中实现 Runnable - Java Swing

java.lang.StackOverflowError on implementing Runnable in a JPanel - Java Swing

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