Java/Swing Components/Clock

A simple Clock

/*
 * 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);
  }
}