Main.java Source code

Introduction

Here is the source code for Main.java

Source

/*
 * Copyright (C) 2002-2003 Colin Bell
 * colbell@users.sourceforge.net
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DateFormat;
import java.util.Calendar;

import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.Timer;
import javax.swing.border.Border;

public class Main {
    public static void main(String[] args) {
        TimePanel label = new TimePanel();

        JOptionPane.showMessageDialog(null, label);

    }
}

/**
 * Time panel. This will show the current time. A timer to update the time is
 * started when the component is added to its parent and stopped when removed
 * from its parent.
 *
 * @author <A HREF="mailto:colbell@users.sourceforge.net">Colin Bell</A>
 */
class TimePanel extends JLabel implements ActionListener {
    /** Timer that updates time. */
    private Timer _timer;

    /** Used to format the displayed date. */
    private DateFormat _fmt = DateFormat.getTimeInstance(DateFormat.LONG);
    private Dimension _prefSize;
    private Calendar _calendar = Calendar.getInstance();

    /**
     * Default ctor.
     */
    public TimePanel() {
        super("", JLabel.CENTER);
    }

    /**
     * Add component to its parent. Start the timer for auto-update.
     */
    public void addNotify() {
        super.addNotify();
        _timer = new Timer(1000, this);
        _timer.start();
    }

    /**
     * Remove component from its parent. Stop the timer.
     */
    public void removeNotify() {
        super.removeNotify();
        if (_timer != null) {
            _timer.stop();
            _timer = null;
        }
    }

    /**
     * Update component with the current time.
     *
     * @param evt
     *          The current event.
     */
    public void actionPerformed(ActionEvent evt) {
        _calendar.setTimeInMillis(System.currentTimeMillis());
        setText(_fmt.format(_calendar.getTime()));
    }

    /**
     * Return the preferred size of this component.
     *
     * @return the preferred size of this component.
     */
    public Dimension getPreferredSize() {
        if (null == _prefSize) {
            // This was originaly done every time.
            // and the count of instantiated objects was amazing
            _prefSize = new Dimension();
            _prefSize.height = 20;
            FontMetrics fm = getFontMetrics(getFont());
            Calendar cal = Calendar.getInstance();
            cal.set(Calendar.HOUR_OF_DAY, 23);
            cal.set(Calendar.MINUTE, 59);
            cal.set(Calendar.SECOND, 59);
            _prefSize.width = fm.stringWidth(_fmt.format(cal.getTime()));
            Border border = getBorder();
            if (border != null) {
                Insets ins = border.getBorderInsets(this);
                if (ins != null) {
                    _prefSize.width += (ins.left + ins.right);
                }
            }
            Insets ins = getInsets();
            if (ins != null) {
                _prefSize.width += (ins.left + ins.right) + 20;
            }
        }
        return _prefSize;
    }
}