组件在绘制之前等待后面的代码执行

Question

我有一个名为 WaitBox 的 class 我想弹出它，显示一个进度条，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 弹出，但它只是白色的，就像在其上绘制组件之前的样子。它运行是它下面的代码（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？

等待框class:

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。

有关详细信息，请参阅 Concurrency in Swing

你的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，记住，Swing是单线程的，但也不是线程安全的。

您应该考虑改用 SwingWorker，它有进步和 PropertyChange 支持。有关详细信息，请参阅 Worker Threads and SwingWorker

其中演示：

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

其他地方

组件在绘制之前等待后面的代码执行

Component waits for later code to execute before it draws

java

swing

jdialog

jprogressbar