Java/Swing Components/Clock

A simple Clock

   <source lang="java">

/*

* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
* 
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java 
* language and environment is gratefully acknowledged.
* 
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/

import java.awt.Dimension; import java.awt.FontMetrics; import java.awt.Graphics; import java.text.DecimalFormat; import java.util.Calendar; /** A simple Clock */ public class Clock extends javax.swing.JComponent {

 protected DecimalFormat tflz, tf;
 protected boolean done = false;
 public Clock() {
   new Thread(new Runnable() {
     public void run() {
       while (!done) {
         Clock.this.repaint(); // request a redraw
         try {
           Thread.sleep(1000);
         } catch (InterruptedException e) { /* do nothing */
         }
       }
     }
   }).start();
   tf = new DecimalFormat("#0");
   tflz = new DecimalFormat("00");
 }
 public void stop() {
   done = true;
 }
 /* paint() - get current time and draw (centered) in Component. */
 public void paint(Graphics g) {
   Calendar myCal = Calendar.getInstance();
   StringBuffer sb = new StringBuffer();
   sb.append(tf.format(myCal.get(Calendar.HOUR)));
   sb.append(":");
   sb.append(tflz.format(myCal.get(Calendar.MINUTE)));
   sb.append(":");
   sb.append(tflz.format(myCal.get(Calendar.SECOND)));
   String s = sb.toString();
   FontMetrics fm = getFontMetrics(getFont());
   int x = (getSize().width - fm.stringWidth(s)) / 2;
   // System.out.println("Size is " + getSize());
   g.drawString(s, x, 10);
 }
 public Dimension getPreferredSize() {
   return new Dimension(100, 30);
 }
 public Dimension getMinimumSize() {
   return new Dimension(50, 10);
 }

}

      </source>