package threadbook.ch09;

import java.awt.*;

import java.lang.reflect.*;

import java.text.*;

import javax.swing.*;

public class DigitalTimer extends JLabel {

private volatile String timeText;

private Thread internalThread;

private volatile boolean noStopRequested;

public DigitalTimer() {

setBorder(BorderFactory.createLineBorder(Color.black));

setHorizontalAlignment(SwingConstants.RIGHT);

setFont(new Font("SansSerif", Font.BOLD, 16));

setText("00000.0"); // use to size component

setMinimumSize(getPreferredSize());

setPreferredSize(getPreferredSize());

setSize(getPreferredSize());

timeText = "0.0";

setText(timeText);

noStopRequested = true;

Runnable r = new Runnable() {

public void run() {

try {

runWork();

} catch ( Exception x ) {

x.printStackTrace();

}

}

};

internalThread = new Thread(r, "DigitalTimer");

internalThread.start();

}

private void runWork() {

long startTime = System.currentTimeMillis();

int tenths = 0;

long normalSleepTime = 100;

long nextSleepTime = 100;

DecimalFormat fmt = new DecimalFormat("0.0");

Runnable updateText = new Runnable() {

public void run() {

setText(timeText);

}

};

while ( noStopRequested ) {

try {

Thread.sleep(nextSleepTime);

tenths++;

long currTime = System.currentTimeMillis();

long elapsedTime = currTime - startTime;

nextSleepTime = normalSleepTime +

( ( tenths * 100 ) - elapsedTime );

if ( nextSleepTime < 0 ) {

nextSleepTime = 0;

}

timeText = fmt.format(elapsedTime / 1000.0);

SwingUtilities.invokeAndWait(updateText);

} catch ( InterruptedException ix ) {

// stop running

return;

} catch ( InvocationTargetException x ) {

// If an exception was thrown inside the

// run() method of the updateText Runnable.

x.printStackTrace();

}

}

}

public void stopRequest() {

noStopRequested = false;

internalThread.interrupt();

}

public boolean isAlive() {

return internalThread.isAlive();

}

public static void main(String[] args) {

DigitalTimer dt = new DigitalTimer();

JPanel p = new JPanel(new FlowLayout());

p.add(dt);

JFrame f = new JFrame("DigitalTimer Demo");

f.setContentPane(p);

f.setSize(250, 100);

f.setVisible(true);

}

}