Mega Code Archive
Extends generic SwingWorker
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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();
}
});
}
}
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