Java/Swing Components/Calendar

A panel that allows the user to select a date.

   <source lang="java">
 

/*

* JCommon : a free general purpose class library for the Java(tm) platform
* 
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
* 
* Project Info:  http://www.jfree.org/jcommon/index.html
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
* USA.  
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
* in the United States and other countries.]
* 
* ---------------------
* DateChooserPanel.java
* ---------------------
* (C) Copyright 2000-2004, by Object Refinery Limited.
*
* Original Author:  David Gilbert (for Object Refinery Limited);
* Contributor(s):   -;
*
* $Id: DateChooserPanel.java,v 1.11 2007/11/02 17:50:36 taqua Exp $
*
* Changes (from 26-Oct-2001)
* --------------------------
* 26-Oct-2001 : Changed package to com.jrefinery.ui.* (DG);
* 08-Dec-2001 : Dropped the getMonths() method (DG);
* 13-Oct-2002 : Fixed errors reported by Checkstyle (DG);
* 02-Nov-2005 : Fixed a bug where the current day-of-the-month is past
*               the end of the newly selected month when the month or year
*               combo boxes are changed - see bug id 1344319 (DG);
*
*/

import java.awt.BorderLayout; import java.awt.Color; import java.awt.Font; import java.awt.GridLayout; import java.awt.Insets; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.text.DateFormatSymbols; import java.util.Calendar; import java.util.Date; import javax.swing.BorderFactory; import javax.swing.JButton; import javax.swing.JComboBox; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.SwingConstants; import javax.swing.UIManager; /**

* A panel that allows the user to select a date.
*
* @author David Gilbert
*/

public class DateChooserPanel extends JPanel implements ActionListener {

   /**
    * The date selected in the panel.
    */
   private Calendar chosenDate;
   /**
    * The color for the selected date.
    */
   private Color chosenDateButtonColor;
   /**
    * The color for dates in the current month.
    */
   private Color chosenMonthButtonColor;
   /**
    * The color for dates that are visible, but not in the current month.
    */
   private Color chosenOtherButtonColor;
   /**
    * The first day-of-the-week.
    */
   private int firstDayOfWeek;
   /**
    * The range used for selecting years.
    */
   private int yearSelectionRange = 20;
   /**
    * The font used to display the date.
    */
   private Font dateFont = new Font("SansSerif", Font.PLAIN, 10);
   /**
    * A combo for selecting the month.
    */
   private JComboBox monthSelector;
   /**
    * A combo for selecting the year.
    */
   private JComboBox yearSelector;
   /**
    * A button for selecting today"s date.
    */
   private JButton todayButton;
   /**
    * An array of buttons used to display the days-of-the-month.
    */
   private JButton[] buttons;
   /**
    * A flag that indicates whether or not we are currently refreshing the 
    * buttons.
    */
   private boolean refreshing = false;
   /**
    * The ordered set of all seven days of a week,
    * beginning with the "firstDayOfWeek".
    */
   private int[] WEEK_DAYS;
   /**
    * Constructs a new date chooser panel, using today"s date as the initial 
    * selection.
    */
   public DateChooserPanel() {
       this(Calendar.getInstance(), false);
   }
   /**
    * Constructs a new date chooser panel.
    *
    * @param calendar     the calendar controlling the date.
    * @param controlPanel a flag that indicates whether or not the "today" 
    *                     button should appear on the panel.
    */
   public DateChooserPanel(final Calendar calendar, 
                           final boolean controlPanel) {
       super(new BorderLayout());
       this.chosenDateButtonColor = UIManager.getColor("textHighlight");
       this.chosenMonthButtonColor = UIManager.getColor("control");
       this.chosenOtherButtonColor = UIManager.getColor("controlShadow");
       // the default date is today...
       this.chosenDate = calendar;
       this.firstDayOfWeek = calendar.getFirstDayOfWeek();
       this.WEEK_DAYS = new int[7];
       for (int i = 0; i < 7; i++) {
           this.WEEK_DAYS[i] = ((this.firstDayOfWeek + i - 1) % 7) + 1;
       }
       add(constructSelectionPanel(), BorderLayout.NORTH);
       add(getCalendarPanel(), BorderLayout.CENTER);
       if (controlPanel) {
           add(constructControlPanel(), BorderLayout.SOUTH);
       }
       setDate(calendar.getTime());
   }
   /**
    * Sets the date chosen in the panel.
    *
    * @param theDate the new date.
    */
   public void setDate(final Date theDate) {
       this.chosenDate.setTime(theDate);
       this.monthSelector.setSelectedIndex(this.chosenDate.get(
               Calendar.MONTH));
       refreshYearSelector();
       refreshButtons();
   }
   /**
    * Returns the date selected in the panel.
    *
    * @return the selected date.
    */
   public Date getDate() {
       return this.chosenDate.getTime();
   }
   /**
    * Handles action-events from the date panel.
    *
    * @param e information about the event that occurred.
    */
   public void actionPerformed(final ActionEvent e) {
       if (e.getActionCommand().equals("monthSelectionChanged")) {
           final JComboBox c = (JComboBox) e.getSource();
           
           // In most cases, changing the month will not change the selected
           // day.  But if the selected day is 29, 30 or 31 and the newly
           // selected month doesn"t have that many days, we revert to the 
           // last day of the newly selected month...
           int dayOfMonth = this.chosenDate.get(Calendar.DAY_OF_MONTH);
           this.chosenDate.set(Calendar.DAY_OF_MONTH, 1);
           this.chosenDate.set(Calendar.MONTH, c.getSelectedIndex());
           int maxDayOfMonth = this.chosenDate.getActualMaximum(
                   Calendar.DAY_OF_MONTH);
           this.chosenDate.set(Calendar.DAY_OF_MONTH, Math.min(dayOfMonth, 
                   maxDayOfMonth));
           refreshButtons();
       }
       else if (e.getActionCommand().equals("yearSelectionChanged")) {
           if (!this.refreshing) {
               final JComboBox c = (JComboBox) e.getSource();
               final Integer y = (Integer) c.getSelectedItem();
               
               // in most cases, changing the year will not change the 
               // selected day.  But if the selected day is Feb 29, and the
               // newly selected year is not a leap year, we revert to 
               // Feb 28...
               int dayOfMonth = this.chosenDate.get(Calendar.DAY_OF_MONTH);
               this.chosenDate.set(Calendar.DAY_OF_MONTH, 1);
               this.chosenDate.set(Calendar.YEAR, y.intValue());
               int maxDayOfMonth = this.chosenDate.getActualMaximum(
                   Calendar.DAY_OF_MONTH);
               this.chosenDate.set(Calendar.DAY_OF_MONTH, Math.min(dayOfMonth, 
                   maxDayOfMonth));
               refreshYearSelector();
               refreshButtons();
           }
       }
       else if (e.getActionCommand().equals("todayButtonClicked")) {
           setDate(new Date());
       }
       else if (e.getActionCommand().equals("dateButtonClicked")) {
           final JButton b = (JButton) e.getSource();
           final int i = Integer.parseInt(b.getName());
           final Calendar cal = getFirstVisibleDate();
           cal.add(Calendar.DATE, i);
           setDate(cal.getTime());
       }
   }
   /**
    * Returns a panel of buttons, each button representing a day in the month.
    * This is a sub-component of the DatePanel.
    *
    * @return the panel.
    */
   private JPanel getCalendarPanel() {
       final JPanel p = new JPanel(new GridLayout(7, 7));
       final DateFormatSymbols dateFormatSymbols = new DateFormatSymbols();
       final String[] weekDays = dateFormatSymbols.getShortWeekdays();
       for (int i = 0; i < this.WEEK_DAYS.length; i++) {
           p.add(new JLabel(weekDays[this.WEEK_DAYS[i]], 
                   SwingConstants.CENTER));
       }
       this.buttons = new JButton[42];
       for (int i = 0; i < 42; i++) {
           final JButton b = new JButton("");
           b.setMargin(new Insets(1, 1, 1, 1));
           b.setName(Integer.toString(i));
           b.setFont(this.dateFont);
           b.setFocusPainted(false);
           b.setActionCommand("dateButtonClicked");
           b.addActionListener(this);
           this.buttons[i] = b;
           p.add(b);
       }
       return p;
   }
   /**
    * Returns the button color according to the specified date.
    *
    * @param theDate the date.
    * @return the color.
    */
   private Color getButtonColor(final Calendar theDate) {
       if (equalDates(theDate, this.chosenDate)) {
           return this.chosenDateButtonColor;
       }
       else if (theDate.get(Calendar.MONTH) == this.chosenDate.get(
               Calendar.MONTH)) {
           return this.chosenMonthButtonColor;
       }
       else {
           return this.chosenOtherButtonColor;
       }
   }
   /**
    * Returns true if the two dates are equal (time of day is ignored).
    *
    * @param c1 the first date.
    * @param c2 the second date.
    * @return boolean.
    */
   private boolean equalDates(final Calendar c1, final Calendar c2) {
       if ((c1.get(Calendar.DATE) == c2.get(Calendar.DATE))
           && (c1.get(Calendar.MONTH) == c2.get(Calendar.MONTH))
           && (c1.get(Calendar.YEAR) == c2.get(Calendar.YEAR))) {
           return true;
       }
       else {
           return false;
       }
   }
   /**
    * Returns the first date that is visible in the grid.  This should always 
    * be in the month preceding the month of the selected date.
    *
    * @return the date.
    */
   private Calendar getFirstVisibleDate() {
       final Calendar c = Calendar.getInstance();
       c.set(this.chosenDate.get(Calendar.YEAR), this.chosenDate.get(
               Calendar.MONTH), 1);
       c.add(Calendar.DATE, -1);
       while (c.get(Calendar.DAY_OF_WEEK) != getFirstDayOfWeek()) {
           c.add(Calendar.DATE, -1);
       }
       return c;
   }
   /**
    * Returns the first day of the week (controls the labels in the date 
    * panel).
    *
    * @return the first day of the week.
    */
   private int getFirstDayOfWeek() {
       return this.firstDayOfWeek;
   }
   /**
    * Update the button labels and colors to reflect date selection.
    */
   private void refreshButtons() {
       final Calendar c = getFirstVisibleDate();
       for (int i = 0; i < 42; i++) {
           final JButton b = this.buttons[i];
           b.setText(Integer.toString(c.get(Calendar.DATE)));
           b.setBackground(getButtonColor(c));
           c.add(Calendar.DATE, 1);
       }
   }
   /**
    * Changes the contents of the year selection JComboBox to reflect the 
    * chosen date and the year range.
    */
   private void refreshYearSelector() {
       if (!this.refreshing) {
           this.refreshing = true;
           this.yearSelector.removeAllItems();
           final Integer[] years = getYears(this.chosenDate.get(
                   Calendar.YEAR));
           for (int i = 0; i < years.length; i++) {
               this.yearSelector.addItem(years[i]);
           }
           this.yearSelector.setSelectedItem(new Integer(this.chosenDate.get(
                   Calendar.YEAR)));
           this.refreshing = false;
       }
   }
   /**
    * Returns a vector of years preceding and following the specified year.  
    * The number of years preceding and following is determined by the 
    * yearSelectionRange attribute.
    *
    * @param chosenYear the selected year.
    * @return a vector of years.
    */
   private Integer[] getYears(final int chosenYear) {
       final int size = this.yearSelectionRange * 2 + 1;
       final int start = chosenYear - this.yearSelectionRange;
       final Integer[] years = new Integer[size];
       for (int i = 0; i < size; i++) {
           years[i] = new Integer(i + start);
       }
       return years;
   }
   /**
    * Constructs a panel containing two JComboBoxes (for the month and year) 
    * and a button (to reset the date to TODAY).
    *
    * @return the panel.
    */
   private JPanel constructSelectionPanel() {
       final JPanel p = new JPanel();
       final int minMonth = this.chosenDate.getMinimum(Calendar.MONTH);
       final int maxMonth = this.chosenDate.getMaximum(Calendar.MONTH);
       final String[] months = new String[maxMonth - minMonth + 1];
       for(int i=0;i<months.length;i++){
         months[i] = ""+i;
       } 
       
       this.monthSelector = new JComboBox(months);
       this.monthSelector.addActionListener(this);
       this.monthSelector.setActionCommand("monthSelectionChanged");
       p.add(this.monthSelector);
       this.yearSelector = new JComboBox(getYears(0));
       this.yearSelector.addActionListener(this);
       this.yearSelector.setActionCommand("yearSelectionChanged");
       p.add(this.yearSelector);
       return p;
   }
   /**
    * Returns a panel that appears at the bottom of the calendar panel - 
    * contains a button for selecting today"s date.
    *
    * @return the panel.
    */
   private JPanel constructControlPanel() {
       final JPanel p = new JPanel();
       p.setBorder(BorderFactory.createEmptyBorder(2, 5, 2, 5));
       this.todayButton = new JButton("Today");
       this.todayButton.addActionListener(this);
       this.todayButton.setActionCommand("todayButtonClicked");
       p.add(this.todayButton);
       return p;
   }
   /**
    * Returns the color for the currently selected date.
    *
    * @return a color.
    */
   public Color getChosenDateButtonColor() {
       return this.chosenDateButtonColor;
   }
   /**
    * Redefines the color for the currently selected date.
    *
    * @param chosenDateButtonColor the new color
    */
   public void setChosenDateButtonColor(final Color chosenDateButtonColor) {
       if (chosenDateButtonColor == null) {
           throw new NullPointerException("UIColor must not be null.");
       }
       final Color oldValue = this.chosenDateButtonColor;
       this.chosenDateButtonColor = chosenDateButtonColor;
       refreshButtons();
       firePropertyChange("chosenDateButtonColor", oldValue, 
               chosenDateButtonColor);
   }
   /**
    * Returns the color for the buttons representing the current month.
    *
    * @return the color for the current month.
    */
   public Color getChosenMonthButtonColor() {
       return this.chosenMonthButtonColor;
   }
   /**
    * Defines the color for the buttons representing the current month.
    *
    * @param chosenMonthButtonColor the color for the current month.
    */
   public void setChosenMonthButtonColor(final Color chosenMonthButtonColor) {
       if (chosenMonthButtonColor == null) {
           throw new NullPointerException("UIColor must not be null.");
       }
       final Color oldValue = this.chosenMonthButtonColor;
       this.chosenMonthButtonColor = chosenMonthButtonColor;
       refreshButtons();
       firePropertyChange("chosenMonthButtonColor", oldValue, 
               chosenMonthButtonColor);
   }
   /**
    * Returns the color for the buttons representing the other months.
    *
    * @return a color.
    */
   public Color getChosenOtherButtonColor() {
       return this.chosenOtherButtonColor;
   }
   /**
    * Redefines the color for the buttons representing the other months.
    *
    * @param chosenOtherButtonColor a color.
    */
   public void setChosenOtherButtonColor(final Color chosenOtherButtonColor) {
       if (chosenOtherButtonColor == null) {
           throw new NullPointerException("UIColor must not be null.");
       }
       final Color oldValue = this.chosenOtherButtonColor;
       this.chosenOtherButtonColor = chosenOtherButtonColor;
       refreshButtons();
       firePropertyChange("chosenOtherButtonColor", oldValue, 
               chosenOtherButtonColor);
   }
   /**
    * Returns the range of years available for selection (defaults to 20).
    * 
    * @return The range.
    */
   public int getYearSelectionRange() {
       return this.yearSelectionRange;
   }
   /**
    * Sets the range of years available for selection.
    * 
    * @param yearSelectionRange  the range.
    */
   public void setYearSelectionRange(final int yearSelectionRange) {
       final int oldYearSelectionRange = this.yearSelectionRange;
       this.yearSelectionRange = yearSelectionRange;
       refreshYearSelector();
       firePropertyChange("yearSelectionRange", oldYearSelectionRange, 
               yearSelectionRange);
   }

}

 </source>
   
  
 
  

Bean to display a month calendar in a JPanel

   <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.BorderLayout; import java.awt.Color; import java.awt.ruponent; import java.awt.Container; import java.awt.FlowLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Calendar; import java.util.GregorianCalendar; import javax.swing.BorderFactory; import javax.swing.JButton; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JPanel; /**

* Bean to display a month calendar in a JPanel. Only works for the Western
* calendar.
* 
* @author Ian F. Darwin, http://www.darwinsys.ru/
* @version $Id: Cal.java,v 1.5 2004/02/09 03:33:45 ian Exp $
*/

public class Cal extends JPanel {

 /** The currently-interesting year (not modulo 1900!) */
 protected int yy;
 /** Currently-interesting month and day */
 protected int mm, dd;
 /** The buttons to be displayed */
 protected JButton labs[][];
 /** The number of day squares to leave blank at the start of this month */
 protected int leadGap = 0;
 /** A Calendar object used throughout */
 Calendar calendar = new GregorianCalendar();
 /** Today"s year */
 protected final int thisYear = calendar.get(Calendar.YEAR);
 /** Today"s month */
 protected final int thisMonth = calendar.get(Calendar.MONTH);
 /** One of the buttons. We just keep its reference for getBackground(). */
 private JButton b0;
 /** The month choice */
 private JComboBox monthChoice;
 /** The year choice */
 private JComboBox yearChoice;
 /**
  * Construct a Cal, starting with today.
  */
 Cal() {
   super();
   setYYMMDD(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
       calendar.get(Calendar.DAY_OF_MONTH));
   buildGUI();
   recompute();
 }
 /**
  * Construct a Cal, given the leading days and the total days
  * 
  * @exception IllegalArgumentException
  *                If year out of range
  */
 Cal(int year, int month, int today) {
   super();
   setYYMMDD(year, month, today);
   buildGUI();
   recompute();
 }
 private void setYYMMDD(int year, int month, int today) {
   yy = year;
   mm = month;
   dd = today;
 }
 String[] months = { "January", "February", "March", "April", "May", "June",
     "July", "August", "September", "October", "November", "December" };
 /** Build the GUI. Assumes that setYYMMDD has been called. */
 private void buildGUI() {
   getAccessibleContext().setAccessibleDescription(
       "Calendar not accessible yet. Sorry!");
   setBorder(BorderFactory.createEtchedBorder());
   setLayout(new BorderLayout());
   JPanel tp = new JPanel();
   tp.add(monthChoice = new JComboBox());
   for (int i = 0; i < months.length; i++)
     monthChoice.addItem(months[i]);
   monthChoice.setSelectedItem(months[mm]);
   monthChoice.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ae) {
       int i = monthChoice.getSelectedIndex();
       if (i >= 0) {
         mm = i;
         // System.out.println("Month=" + mm);
         recompute();
       }
     }
   });
   monthChoice.getAccessibleContext().setAccessibleName("Months");
   monthChoice.getAccessibleContext().setAccessibleDescription(
       "Choose a month of the year");
   tp.add(yearChoice = new JComboBox());
   yearChoice.setEditable(true);
   for (int i = yy - 5; i < yy + 5; i++)
     yearChoice.addItem(Integer.toString(i));
   yearChoice.setSelectedItem(Integer.toString(yy));
   yearChoice.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ae) {
       int i = yearChoice.getSelectedIndex();
       if (i >= 0) {
         yy = Integer.parseInt(yearChoice.getSelectedItem()
             .toString());
         // System.out.println("Year=" + yy);
         recompute();
       }
     }
   });
   add(BorderLayout.CENTER, tp);
   JPanel bp = new JPanel();
   bp.setLayout(new GridLayout(7, 7));
   labs = new JButton[6][7]; // first row is days
   bp.add(b0 = new JButton("S"));
   bp.add(new JButton("M"));
   bp.add(new JButton("T"));
   bp.add(new JButton("W"));
   bp.add(new JButton("R"));
   bp.add(new JButton("F"));
   bp.add(new JButton("S"));
   ActionListener dateSetter = new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       String num = e.getActionCommand();
       if (!num.equals("")) {
         // set the current day highlighted
         setDayActive(Integer.parseInt(num));
         // When this becomes a Bean, you can
         // fire some kind of DateChanged event here.
         // Also, build a similar daySetter for day-of-week btns.
       }
     }
   };
   // Construct all the buttons, and add them.
   for (int i = 0; i < 6; i++)
     for (int j = 0; j < 7; j++) {
       bp.add(labs[i][j] = new JButton(""));
       labs[i][j].addActionListener(dateSetter);
     }
   add(BorderLayout.SOUTH, bp);
 }
 public final static int dom[] = { 31, 28, 31, 30, /* jan feb mar apr */
 31, 30, 31, 31, /* may jun jul aug */
 30, 31, 30, 31 /* sep oct nov dec */
 };
 /** Compute which days to put where, in the Cal panel */
 protected void recompute() {
   // System.out.println("Cal::recompute: " + yy + ":" + mm + ":" + dd);
   if (mm < 0 || mm > 11)
     throw new IllegalArgumentException("Month " + mm
         + " bad, must be 0-11");
   clearDayActive();
   calendar = new GregorianCalendar(yy, mm, dd);
   // Compute how much to leave before the first.
   // getDay() returns 0 for Sunday, which is just right.
   leadGap = new GregorianCalendar(yy, mm, 1).get(Calendar.DAY_OF_WEEK) - 1;
   // System.out.println("leadGap = " + leadGap);
   int daysInMonth = dom[mm];
   if (isLeap(calendar.get(Calendar.YEAR)) && mm > 1)
     ++daysInMonth;
   // Blank out the labels before 1st day of month
   for (int i = 0; i < leadGap; i++) {
     labs[0][i].setText("");
   }
   // Fill in numbers for the day of month.
   for (int i = 1; i <= daysInMonth; i++) {
     JButton b = labs[(leadGap + i - 1) / 7][(leadGap + i - 1) % 7];
     b.setText(Integer.toString(i));
   }
   // 7 days/week * up to 6 rows
   for (int i = leadGap + 1 + daysInMonth; i < 6 * 7; i++) {
     labs[(i) / 7][(i) % 7].setText("");
   }
   // Shade current day, only if current month
   if (thisYear == yy && mm == thisMonth)
     setDayActive(dd); // shade the box for today
   // Say we need to be drawn on the screen
   repaint();
 }
 /**
  * isLeap() returns true if the given year is a Leap Year.
  * 
  * "a year is a leap year if it is divisible by 4 but not by 100, except
  * that years divisible by 400 *are* leap years." -- Kernighan & Ritchie,
  * _The C Programming Language_, p 37.
  */
 public boolean isLeap(int year) {
   if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
     return true;
   return false;
 }
 /** Set the year, month, and day */
 public void setDate(int yy, int mm, int dd) {
   // System.out.println("Cal::setDate");
   this.yy = yy;
   this.mm = mm; // starts at 0, like Date
   this.dd = dd;
   recompute();
 }
 /** Unset any previously highlighted day */
 private void clearDayActive() {
   JButton b;
   // First un-shade the previously-selected square, if any
   if (activeDay > 0) {
     b = labs[(leadGap + activeDay - 1) / 7][(leadGap + activeDay - 1) % 7];
     b.setBackground(b0.getBackground());
     b.repaint();
     activeDay = -1;
   }
 }
 private int activeDay = -1;
 /** Set just the day, on the current month */
 public void setDayActive(int newDay) {
   clearDayActive();
   // Set the new one
   if (newDay <= 0)
     dd = new GregorianCalendar().get(Calendar.DAY_OF_MONTH);
   else
     dd = newDay;
   // Now shade the correct square
   Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
   square.setBackground(Color.red);
   square.repaint();
   activeDay = newDay;
 }
 /** For testing, a main program */
 public static void main(String[] av) {
   JFrame f = new JFrame("Cal");
   Container c = f.getContentPane();
   c.setLayout(new FlowLayout());
   // for this test driver, hardcode 1995/02/10.
   c.add(new Cal(1995, 2 - 1, 10));
   // and beside it, the current month.
   c.add(new Cal());
   f.pack();
   f.setVisible(true);
 }

}

 </source>
   
  
 
  

Calendar in a JWindow

   <source lang="java">
 

/* Swing Hacks Tips and Tools for Killer GUIs By Joshua Marinacci, Chris Adamson First Edition June 2005 Series: Hacks ISBN: 0-596-00907-0 Pages: 542 website: http://www.oreilly.ru/catalog/swinghks/

• /

import java.awt.Color; import java.awt.Container; import java.awt.Dimension; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Point; import java.awt.RenderingHints; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; public class CalendarHack extends JPanel {

 protected Image background = new ImageIcon("calendar.png").getImage();
 protected Image highlight = new ImageIcon("highlight.png").getImage();
 protected Image day_img = new ImageIcon("day.png").getImage();
 protected SimpleDateFormat month = new SimpleDateFormat("MMMM");
 protected SimpleDateFormat year = new SimpleDateFormat("yyyy");
 protected SimpleDateFormat day = new SimpleDateFormat("d");
 protected Date date = new Date();
 public void setDate(Date date) {
   this.date = date;
 }
 public CalendarHack() {
   this.setPreferredSize(new Dimension(300, 280));
 }
 public void paintComponent(Graphics g) {
   ((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING,
       RenderingHints.VALUE_ANTIALIAS_ON);
   g.drawImage(background, 0, 0, null);
   g.setColor(Color.black);
   g.setFont(new Font("SansSerif", Font.PLAIN, 18));
   g.drawString(month.format(date), 34, 36);
   g.setColor(Color.white);
   g.drawString(year.format(date), 235, 36);
   Calendar today = Calendar.getInstance();
   today.setTime(date);
   Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.set(Calendar.DATE, 1);
   cal.add(Calendar.DATE, -cal.get(Calendar.DAY_OF_WEEK) + 1);
   for (int week = 0; week < 6; week++) {
     for (int d = 0; d < 7; d++) {
       Image img = day_img;
       Color col = Color.black;
       // only draw if it"s actually in this month
       if (cal.get(Calendar.MONTH) == today.get(Calendar.MONTH)) {
         if (cal.equals(today)) {
           img = highlight;
           col = Color.white;
         }
         g.drawImage(img, d * 30 + 46, week * 29 + 81, null);
         g.drawString(day.format(cal.getTime()), d * 30 + 46 + 4, week * 29 + 81 + 20);
       }
       cal.add(Calendar.DATE, +1);
     }
   }
 }
 public static void main(String[] args) {
   JFrame frame = new JFrame();
   CalendarHack ch = new CalendarHack();
   ch.setDate(new Date());
   frame.getContentPane().add(ch);
   frame.setUndecorated(true);
   MoveMouseListener mml = new MoveMouseListener(ch);
   ch.addMouseListener(mml);
   ch.addMouseMotionListener(mml);
   frame.pack();
   frame.setVisible(true);
 }

} class MoveMouseListener implements MouseListener, MouseMotionListener {

 JComponent target;
 Point start_drag;
 Point start_loc;
 public MoveMouseListener(JComponent target) {
   this.target = target;
 }
 public static JFrame getFrame(Container target) {
   if (target instanceof JFrame) {
     return (JFrame) target;
   }
   return getFrame(target.getParent());
 }
 Point getScreenLocation(MouseEvent e) {
   Point cursor = e.getPoint();
   Point target_location = this.target.getLocationOnScreen();
   return new Point((int) (target_location.getX() + cursor.getX()),
       (int) (target_location.getY() + cursor.getY()));
 }
 public void mouseClicked(MouseEvent e) {
 }
 public void mouseEntered(MouseEvent e) {
 }
 public void mouseExited(MouseEvent e) {
 }
 public void mousePressed(MouseEvent e) {
   this.start_drag = this.getScreenLocation(e);
   this.start_loc = this.getFrame(this.target).getLocation();
 }
 public void mouseReleased(MouseEvent e) {
 }
 public void mouseDragged(MouseEvent e) {
   Point current = this.getScreenLocation(e);
   Point offset = new Point((int) current.getX() - (int) start_drag.getX(), (int) current.getY()
       - (int) start_drag.getY());
   JFrame frame = this.getFrame(target);
   Point new_location = new Point((int) (this.start_loc.getX() + offset.getX()),
       (int) (this.start_loc.getY() + offset.getY()));
   frame.setLocation(new_location);
 }
 public void mouseMoved(MouseEvent e) {
 }

}

 </source>
   
  
 
  

Paint a calendar

   <source lang="java">
  

import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import javax.swing.JFrame; import javax.swing.JPanel; public class Main extends JPanel {

 SimpleDateFormat month = new SimpleDateFormat("MMMM");
 SimpleDateFormat year = new SimpleDateFormat("yyyy");
 SimpleDateFormat day = new SimpleDateFormat("d");
 Date date = new Date();
 public void setDate(Date date) {
   this.date = date;
 }
 public void paintComponent(Graphics g) {
   ((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
   g.fillRect(0, 0, getWidth(), getHeight());
   g.setColor(Color.black);
   g.drawString(month.format(date), 34, 36);
   g.setColor(Color.white);
   g.drawString(year.format(date), 235, 36);
   Calendar today = Calendar.getInstance();
   today.setTime(date);
   Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.set(Calendar.DATE, 1);
   cal.add(Calendar.DATE, -cal.get(Calendar.DAY_OF_WEEK) + 1);
   for (int week = 0; week < 6; week++) {
     for (int d = 0; d < 7; d++) {
       Color col = Color.black;
         g.drawString(day.format(cal.getTime()), d * 30 + 46 + 4,
             week * 29 + 81 + 20);
       cal.add(Calendar.DATE, +1);
     }
   }
 }
 public static void main(String[] args) {
   JFrame frame = new JFrame();
   frame.setPreferredSize(new Dimension(300, 280));
   Main ch = new Main();
   ch.setDate(new Date());
   frame.getContentPane().add(ch);
   frame.setUndecorated(true);
   frame.pack();
   frame.setVisible(true);
 }

}

 </source>