java - JDialog 没有出现

Question

该程序大部分运行正常，但没有打开任何窗口。它应该在桌面右下角显示一个小对话框。但是对于另一个人来说，编译相同的代码没有问题。我们有相同的 Java 运行时 (1.8_u40)。我该如何解决这个问题？

我把代码放在下面:

import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.RoundRectangle2D;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JProgressBar;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ProgressDialog {
    private JDialog dialogFrame;
    private JProgressBar progressBar;
    private JLabel headingLabel;
    private Uploader callerUploader;

    public ProgressDialog() {

        dialogFrame = new JDialog();
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException
                | UnsupportedLookAndFeelException ex) {
            System.err.println(ex.toString());
        }

        dialogFrame.setSize(200, 50);
        dialogFrame.setLayout(new GridBagLayout());

        GridBagConstraints constraints = new GridBagConstraints();

        constraints.gridx = 0;
        constraints.gridy = 0;
        constraints.weightx = 1.0;
        constraints.weighty = 1.0;
        constraints.insets = new Insets(5, 5, 5, 5);

        headingLabel = new JLabel();
        Font f = headingLabel.getFont();
        f = new Font(f.getFontName(), Font.BOLD, f.getSize());
        headingLabel.setFont(f);
        headingLabel.setOpaque(false);
        dialogFrame.add(headingLabel, constraints);
        dialogFrame.setUndecorated(true);

        // Bottone
        constraints.gridx = 1;
        constraints.gridy = 0;
        constraints.weightx = 0;
        constraints.weighty = 0;

        JButton xButton = new JButton("X");
        xButton.setMargin(new Insets(1, 4, 1, 4));
        xButton.setFocusable(false);
        dialogFrame.add(xButton, constraints);

        // Progress bar
        constraints.gridx = 0;
        constraints.gridy = 1;
        constraints.weightx = 1.0;
        constraints.weighty = 1.0;
        constraints.gridwidth = 2;

        progressBar = new JProgressBar();
        progressBar.setMaximum(100);
        progressBar.setMinimum(0);
        Dimension dim = new Dimension();
        dim.width = 130;
        dim.height = 20;
        progressBar.setMinimumSize(dim);
        progressBar.setStringPainted(true);
        progressBar.setBorderPainted(true);
        dialogFrame.add(progressBar, constraints);

        xButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                dialogFrame.dispose();
                stoppedUploaderClose();
            }
        });
    }

    private void autoPosition() {
        // Per il posizionamento in basso a destra
        Dimension scrSize = Toolkit.getDefaultToolkit().getScreenSize();
        // altezza taskbar
        Insets toolHeight = Toolkit.getDefaultToolkit().getScreenInsets(dialogFrame.getGraphicsConfiguration());
        dialogFrame.setLocation(scrSize.width - 5 - dialogFrame.getWidth(), scrSize.height - 5 - toolHeight.bottom
                - dialogFrame.getHeight());
    }

    public void destroy() {
        new Thread() {
            @Override
            public void run() {
                try {
                    Thread.sleep(500);
                    for (float i = 1.00f; i >= 0; i -= 0.01f) {
                        dialogFrame.setOpacity(i);
                        Thread.sleep(15);
                    }
                    dialogFrame.dispose();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            };
        }.start();

    }

    public void setUploader(Uploader callerUploader) {
        this.callerUploader = callerUploader;
    }

    public void set(int n) {
        progressBar.setValue(n);
        progressBar.setString(n + "");
    }

    public void setMessage(String headingLabel) {
        this.headingLabel.setText(headingLabel);
        autoPosition();
        dialogFrame.setShape(new RoundRectangle2D.Double(1, 1, 200, 50, 20, 20));
        dialogFrame.setVisible(true);
    }

    public void setWait() {
        headingLabel.setText("Waiting link...");
    }

    public void close() {
        dialogFrame.dispose();
    }

    public void stoppedUploaderClose() {
        try {
            callerUploader.stopUpload();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Answer 1

您正在从后台线程中进行 Swing 调用以更改 GUI 的 Swing 组件的状态，这可能而且将会导致不可预测的错误。最好使用 Swing 计时器而不是 Thread.sleep(...)，因为计时器的 ActionListener 中的所有代码都在 Swing 事件线程上调用。

另外，我不得不怀疑

1. Uploader 类所做的，...可能它创建了长时间运行的代码，这引出了一个问题，它是否在后台线程中被适本地调用？这看起来是 SwingWorker 的好地方。
2. 如何调用此对话代码？

要获得更直接的帮助，请考虑创建并发布 sscce或 minimal example program/mcve您将代码压缩为仍然可以编译和运行的最小位，没有外部依赖性(例如需要链接到数据库或图像)，没有与您的问题无关的额外代码，但仍然可以证明您的问题。

编辑:好的，我通常不这样做，但我查看了您在 GitHub project link 中的代码，正如我所怀疑的那样，Uploader 在 Swing 事件线程 上执行长时间运行的代码，并调用您在上面发布的此类。我建议您将 SwingWorker 用于长时间运行的代码，使用其 setProgress(...) 方法将其进度状态从 0 更改为 100，并使用 PropertyChangeListener 来监听更改为该状态，然后基于此设置 JProgressBar 的值。这将需要您做很多工作，但非常值得。详情看:Lesson: Concurrency in Swing

我有一些示例 SwingWorker 程序，您可以在这里找到:

• Cant get JProgressBar to update from SwingWorker class
• MVC Progress Bar Threading
• How do I make my SwingWorker example work properly?
• JProgressBar without JButton and PropertyChangeListener
• Understanding Java ExecutorService