Java Tutorial/Swing/SwingWorker

14. extends generic SwingWorker

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.border.Border;
public class Flipper extends JFrame implements ActionListener {
  private final GridBagConstraints constraints;
  private final JTextField headsText, totalText, devText;
  private final Border border = BorderFactory.createLoweredBevelBorder();
  private final JButton startButton, stopButton;
  private FlipTask flipTask;
  private JTextField makeText() {
    JTextField t = new JTextField(20);
    t.setEditable(false);
    t.setHorizontalAlignment(JTextField.RIGHT);
    t.setBorder(border);
    getContentPane().add(t, constraints);
    return t;
  }
  private JButton makeButton(String caption) {
    JButton b = new JButton(caption);
    b.setActionCommand(caption);
    b.addActionListener(this);
    getContentPane().add(b, constraints);
    return b;
  }
  public Flipper() {
    super("Flipper");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Make text boxes
    getContentPane().setLayout(new GridBagLayout());
    constraints = new GridBagConstraints();
    constraints.insets = new Insets(3, 10, 3, 10);
    headsText = makeText();
    totalText = makeText();
    devText = makeText();
    // Make buttons
    startButton = makeButton("Start");
    stopButton = makeButton("Stop");
    stopButton.setEnabled(false);
    // Display the window.
    pack();
    setVisible(true);
  }
  private static class FlipPair {
    private final long heads, total;
    FlipPair(long heads, long total) {
      this.heads = heads;
      this.total = total;
    }
  }
  private class FlipTask extends SwingWorker<Void, FlipPair> {
    @Override
    protected Void doInBackground() {
      long heads = 0;
      long total = 0;
      Random random = new Random();
      while (!isCancelled()) {
        total++;
        if (random.nextBoolean()) {
          heads++;
        }
        publish(new FlipPair(heads, total));
      }
      return null;
    }
    @Override
    protected void process(List<FlipPair> pairs) {
      FlipPair pair = pairs.get(pairs.size() - 1);
      headsText.setText(String.format("%d", pair.heads));
      totalText.setText(String.format("%d", pair.total));
      devText.setText(String.format("%.10g", ((double) pair.heads)
          / ((double) pair.total) - 0.5));
    }
  }
  public void actionPerformed(ActionEvent e) {
    if ("Start" == e.getActionCommand()) {
      startButton.setEnabled(false);
      stopButton.setEnabled(true);
      (flipTask = new FlipTask()).execute();
    } else if ("Stop" == e.getActionCommand()) {
      startButton.setEnabled(true);
      stopButton.setEnabled(false);
      flipTask.cancel(true);
      flipTask = null;
    }
  }
  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        new Flipper();
      }
    });
  }
}

14. Progress Monitor and Swingworker

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.awt.BorderLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ProgressMonitor;
import javax.swing.SwingWorker;
public class ProgressMonitorDemo extends JPanel implements ActionListener,
    PropertyChangeListener {
  private ProgressMonitor progressMonitor;
  private JButton startButton;
  private JTextArea taskOutput;
  private Task task;
  class Task extends SwingWorker<Void, Void> {
    @Override
    public Void doInBackground() {
      Random random = new Random();
      int progress = 0;
      setProgress(0);
      try {
        Thread.sleep(1000);
        while (progress < 100 && !isCancelled()) {
          // Sleep for up to one second.
          Thread.sleep(random.nextInt(1000));
          // Make random progress.
          progress += random.nextInt(10);
          setProgress(Math.min(progress, 100));
        }
      } catch (InterruptedException ignore) {
      }
      return null;
    }
    @Override
    public void done() {
      Toolkit.getDefaultToolkit().beep();
      startButton.setEnabled(true);
      progressMonitor.setProgress(0);
    }
  }
  public ProgressMonitorDemo() {
    super(new BorderLayout());
    // Create the demo"s UI.
    startButton = new JButton("Start");
    startButton.setActionCommand("start");
    startButton.addActionListener(this);
    taskOutput = new JTextArea(5, 20);
    taskOutput.setMargin(new Insets(5, 5, 5, 5));
    taskOutput.setEditable(false);
    add(startButton, BorderLayout.PAGE_START);
    add(new JScrollPane(taskOutput), BorderLayout.CENTER);
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
  }
  /**
   * Invoked when the user presses the start button.
   */
  public void actionPerformed(ActionEvent evt) {
    progressMonitor = new ProgressMonitor(ProgressMonitorDemo.this,
        "Running a Long Task", "", 0, 100);
    progressMonitor.setProgress(0);
    task = new Task();
    task.addPropertyChangeListener(this);
    task.execute();
    startButton.setEnabled(false);
  }
  /**
   * Invoked when task"s progress property changes.
   */
  public void propertyChange(PropertyChangeEvent evt) {
    if ("progress" == evt.getPropertyName()) {
      int progress = (Integer) evt.getNewValue();
      progressMonitor.setProgress(progress);
      String message = String.format("Completed %d%%.\n", progress);
      progressMonitor.setNote(message);
      taskOutput.append(message);
      if (progressMonitor.isCanceled() || task.isDone()) {
        Toolkit.getDefaultToolkit().beep();
        if (progressMonitor.isCanceled()) {
          task.cancel(true);
          taskOutput.append("Task canceled.\n");
        } else {
          taskOutput.append("Task completed.\n");
        }
        startButton.setEnabled(true);
      }
    }
  }
  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("ProgressMonitorDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Create and set up the content pane.
    JComponent newContentPane = new ProgressMonitorDemo();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);
    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }
  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application"s GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}

14. SwingWorker in Java 6

import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.List;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingWorker;
public class Main{
  public static void main(String[] args) {
    final JProgressBar progressBar = new JProgressBar(0, 10);
    final CounterTask task = new CounterTask();
    task.addPropertyChangeListener(new PropertyChangeListener() {
      public void propertyChange(PropertyChangeEvent evt) {
        if ("progress".equals(evt.getPropertyName())) {
          progressBar.setValue((Integer) evt.getNewValue());
        }
      }
    });
    JButton startButton = new JButton("Start");
    startButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        task.execute();
      }
    });
    JButton cancelButton = new JButton("Cancel");
    cancelButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        task.cancel(true);
      }
    });
    JPanel buttonPanel = new JPanel();
    buttonPanel.add(startButton);
    buttonPanel.add(cancelButton);
    JPanel cp = new JPanel();
    LayoutManager layout = new BoxLayout(cp, BoxLayout.Y_AXIS);
    cp.setLayout(layout);
    cp.add(buttonPanel);
    cp.add(progressBar);
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(cp);
    frame.pack();
    frame.setVisible(true);
  }
}
class CounterTask extends SwingWorker<Integer, Integer> {
  int DELAY = 1000;
  @Override
  protected Integer doInBackground() throws Exception {
    int i = 0;
    int count = 10;
    while (!isCancelled() && i < count) {
      i++;
      publish(new Integer[] { i });
      setProgress(count * i / count);
      Thread.sleep(DELAY);
    }
    return count;
  }   
  protected void process(List<Integer> chunks) {
      System.out.println(chunks);
  }
  @Override
  protected void done() {
    if (isCancelled())
      System.out.println("Cancelled !");
    else
      System.out.println("Done !");
  }
}

14. Use SwingWorker to perform background tasks

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.SwingWorker;
public class Main extends JFrame {
  public Main() {
    this.setLayout(new FlowLayout());
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton processButton = new JButton("Start");
    JButton helloButton = new JButton("Hello");
    processButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent event) {
        MyTask process = new MyTask();
        try {
          process.execute();
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    });
    helloButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        JOptionPane.showMessageDialog(null, "Hello There");
      }
    });
    this.getContentPane().add(processButton);
    this.getContentPane().add(helloButton);
    this.pack();
    setVisible(true);
  }
  public static void main(String[] args) {
    new Main();
  }
}
class MyTask extends SwingWorker {
  protected Object doInBackground() throws Exception {
    Integer result = new Integer(0);
    for (int i = 0; i < 10; i++) {
      result += i * 10;
      try {
        Thread.sleep(5000);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
    return result;
  }
}