java - 组件在绘制之前等待稍后的代码执行

Question

我有一个名为 WaitBox 的类，我想弹出该类，显示进度条，然后在进度条达到 100% 时关闭。现在，它弹出了，但奇怪的是，它等到代码完成后才在WaitBox中绘制组件(进度条)...

当我运行下面的代码时，JDialog 会弹出，但它只是白色的，就像在上面绘制组件之前的样子一样。它运行下面的代码(嵌套的 for 循环)，完成后，它在 JDialog 上绘制组件。为什么会发生这种情况？我该如何解决它？

WaitBox 类:

public class WaitBox extends JDialog implements Runnable {
private static final long serialVersionUID = 1L;

private int width = 450;
private int height = 200;
public static int widthOfBar = 400;
private int heightOfBar = 50;
private JPanel container;
private JProgressBar progressBar;
private Thread thread;
private boolean running = false;

public WaitBox() {
    initializeComponents();
    add(container);
    pack();
    setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
    setTitle("Loading...");
    setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    setResizable(false);
    setLocationRelativeTo(null);
    setVisible(true);
}

private void initializeComponents() {
    container = new JPanel();
    container.setPreferredSize(new Dimension(width, height));
    progressBar = new JProgressBar(0, widthOfBar);
    progressBar.setPreferredSize(new Dimension(widthOfBar, heightOfBar));
    progressBar.setStringPainted(true);
    progressBar.setValue(0);
    container.add(progressBar);
}

public void run() {
    while (running) {
        System.out.println(Fill.currentPos);
        progressBar.setValue((int) Fill.currentPos);
        if (progressBar.getValue() >= widthOfBar) running = false;
    }
    stop();
}

public synchronized void start() {
    running = true;
    thread = new Thread(this);
    thread.start();
}

public synchronized void stop() {
    running = false;
    try {
        thread.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    setCursor(null);
    dispose();
}

}

如何称呼:

WaitBox waitBox = new WaitBox();
waitBox.start();
for (int yy = 0; yy < Constants.map_height; yy++) {
    for (int xx = 0; xx < Constants.map_width; xx++) {
        image.setRGB(xx * 32, yy * 32, 32, 32, pixels, 0, 32);
    }
}

Answer 1

您的 stop 方法正在等待 thread 结束，这会阻塞事件调度线程。

参见Concurrency in Swing了解更多详情

您的 run 方法违反了 Swing 的单线程规则，从事件调度线程外部更新 UI，请记住，Swing 是单线程的，但也不是线程安全的。

您应该考虑使用 SwingWorker，它具有进度和 PropertyChange 支持。请参阅Worker Threads and SwingWorker了解更多详情

这被证明:

• Issues with SwingWorker and JProgressBar
• java swingworker thread to update main Gui
• Progress Bar Java
• JProgressBar isn't progressing
• SwingWorker in another SwingWorker's done method
• SwingWorker In multithreaded Jframes
• Progress Bar Java

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