【问题标题】:progress bar not updating with threads进度条不随线程更新
【发布时间】:2012-05-22 21:49:58
【问题描述】:

好的,我又来这里问一个愚蠢的问题。我有一个自定义对话框框架,上面有进度条。所以我也有一个遗传算法(它的工作时间相当长)。

据我了解所有情况,我需要为算法、进度条执行单独的线程,并将主线程留给对话框(让他有机会响应用户操作)。所以我尝试实现这一点,并得到以下结果:

public class ScheduleDialog extends JDialog {

    private final JPanel contentPanel = new JPanel();

    private static Data data;
    private static GeneticEngine geneticEngine;
    private static Schedule schedule;

    private static JProgressBar progressBar;
    private static JLabel statusLabel;

    public static void showProgress() {
        try {
            ScheduleDialog dialog = new ScheduleDialog();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
            startScheduleComposing();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void startScheduleComposing() {
        BackGroundWorker backGroundWorker = new BackGroundWorker();
        GeneticEngineWorker geneticEngineWorker = new GeneticEngineWorker();
        new Thread(geneticEngineWorker).start();
        new Thread(backGroundWorker).start();
    }

    private ScheduleDialog() {

        this.data = Data.getInstance();

        setTitle("");
        setModal(true);
        setBounds(100, 100, 405, 150);
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension dialogSize = getSize();
        setLocation((screenSize.width - dialogSize.width) / 2, (screenSize.height - dialogSize.height) / 2);
        getContentPane().setLayout(new BorderLayout());
        contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
        getContentPane().add(contentPanel, BorderLayout.CENTER);
        contentPanel.setLayout(new GridLayout(0, 1, 0, 0));
        {
            progressBar = new JProgressBar();
            progressBar.setBackground(Color.RED);
            contentPanel.add(progressBar);
        }
        {
            statusLabel = new JLabel("");
            contentPanel.add(statusLabel);
        }
        {
            JPanel buttonPane = new JPanel();
            buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
            getContentPane().add(buttonPane, BorderLayout.SOUTH);
            {
                JButton okButton = new JButton("Прервать");
                okButton.setActionCommand("OK");
                buttonPane.add(okButton);
                getRootPane().setDefaultButton(okButton);
            }
        }


    }

    protected static class BackGroundWorker implements Runnable {
        @Override
        public void run() {
          while(true){
            int barValue = 100 - (geneticEngine.getCurrentBestFitness() / geneticEngine.getInitialFitness());
            progressBar.setValue(barValue);
            progressBar.repaint();
            statusLabel.setText(String.valueOf(geneticEngine.getCurrentBestFitness()));
            statusLabel.repaint();
            try{
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                e.printStackTrace();  
            }
          }
        }
    }

    protected static class GeneticEngineWorker implements Runnable{

        @Override
        public void run() {
            geneticEngine = new GeneticEngine(data);
            schedule = geneticEngine.GeneticAlgorithm();
        }
    }
}

看来,new Thread(geneticEngineWorker).start(); 正在工作,但进度条没有任何反应。我认为这部分代码:

private static void startScheduleComposing() {
            BackGroundWorker backGroundWorker = new BackGroundWorker();
            GeneticEngineWorker geneticEngineWorker = new GeneticEngineWorker();
            new Thread(geneticEngineWorker).start();
            new Thread(backGroundWorker).start();
        }

只有在new Thread(geneticEngineWorker).start(); 停止之后才会执行new Thread(backGroundWorker).start();
所以,如果我是对的,你能告诉我如何重组代码来完成这项工作,如果我错了,你能指出我的错误吗?

提前谢谢大家!


添加

我调试了它,我想,backGroundWorker只有在genericEngineWorker结束或用户关闭对话框后才开始工作(这种情况下例外);

【问题讨论】:

  • 也许我遗漏了一些东西,但更新 ProgressBar 的线程只更新了一次 Bar,然后在完成前休眠 10 秒。检查 Timer 和 TimerTask 类以安排重复更新。
  • 对不起,我不小心发布了旧版本。已编辑。实际上如果我添加一个while循环没有任何改变,我认为它没有问题。
  • 你的理解是错误的。与所有 Swing 组件一样,进度条必须始终从 EDT 更新。不是来自后台线程。
  • 无法运行的理论表明您没有在 EDT-Event Dispatcher Thread 上更新您的 GUI,您需要使用 SwingWorker 或在 EDT 上自己进行更新。

标签: java multithreading swing jprogressbar


【解决方案1】:

是的,有两种基本的使用方式

SwingWorker,需要对Java Essential Classes inc 有最深入的了解。 Generics也是

Runnable#Thread 只需要将 GUI 的输出包装到 invokeLater()

关于想法Runnable#ThreadJProgressBar 都在JTable 中不需要特别努力的简单示例,这意味着代码行model.setValueAt(value, row, column); 应该被包装到invokeLater 中,但在其他手中setText() 被声明作为线程安全的,我建议在所有情况下都将其包装到 invokeLater

import java.awt.Component;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellRenderer;

public class TableWithProgressBars {

    private static final int maximum = 100;

    public void createGUI() {
        final JFrame frame = new JFrame("Progressing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Integer[] oneRow = {0, 0, 0, 0};
        String[] headers = {"One", "Two", "Three", "Four"};
        Integer[][] data = {oneRow, oneRow, oneRow, oneRow, oneRow,};
        final DefaultTableModel model = new DefaultTableModel(data, headers);
        final JTable table = new JTable(model);
        table.setDefaultRenderer(Object.class, new ProgressRenderer(0, maximum));
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        frame.add(new JScrollPane(table));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        new Thread(new Runnable() {

            @Override
            public void run() {
                Object waiter = new Object();
                synchronized (waiter) {
                    int rows = model.getRowCount();
                    int columns = model.getColumnCount();
                    Random random = new Random(System.currentTimeMillis());
                    boolean done = false;
                    while (!done) {
                        int row = random.nextInt(rows);
                        int column = random.nextInt(columns);
                        Integer value = (Integer) model.getValueAt(row, column);
                        value++;
                        if (value <= maximum) {
                            model.setValueAt(value, row, column);
                            try {
                                waiter.wait(15);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        done = true;
                        for (row = 0; row < rows; row++) {
                            for (column = 0; column < columns; column++) {
                                if (!model.getValueAt(row, column).equals(maximum)) {
                                    done = false;
                                    break;
                                }
                            }
                            if (!done) {
                                break;
                            }
                        }
                    }
                    frame.setTitle("All work done");
                }
            }
        }).start();
    }

    public static class ProgressRenderer extends JProgressBar implements TableCellRenderer {

        private static final long serialVersionUID = 1L;

        public ProgressRenderer(int min, int max) {
            super(min, max);
            this.setStringPainted(true);
        }

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value,
                boolean isSelected, boolean hasFocus, int row, int column) {
            this.setValue((Integer) value);
            return this;
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TableWithProgressBars().createGUI();
            }
        });

    }
}

【讨论】:

  • 这是一个很好的例子,但我认为 getTableCellRendererComponent 的覆盖和进度的隐式设置对于不熟悉表格模型和东西的人来说很难掌握:D
  • @mr.nothing 请read my question ,可以用最复杂的方式来演示
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