/* * 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. */ package concurrency;import java.util.List;import java.util.Random;import java.awt.event.ActionListener;import java.awt.event.ActionEvent;import java.awt.GridBagLayout;import java.awt.GridBagConstraints;import java.awt.Insets;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JTextField;import javax.swing.SwingUtilities;import javax.swing.border.Border;import javax.swing.BorderFactory;import javax.swing.SwingWorker;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();            }        });    }}