Java Tutorial/Swing/JPanel

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A basic panel that displays a small up or down arrow.

/* 
 * 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.]
 * 
 * ---------------
 * ArrowPanel.java
 * ---------------
 * (C) Copyright 2002-2004, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: ArrowPanel.java,v 1.6 2007/11/02 17:50:36 taqua Exp $
 *
 * Changes
 * -------
 * 25-Sep-2002 : Version 1 (DG);
 * 13-Oct-2002 : Added Javadocs (DG);
 *
 */
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.Polygon;
import java.awt.Shape;
import java.awt.geom.Rectangle2D;
import javax.swing.JPanel;
/**
 * A basic panel that displays a small up or down arrow.
 * 
 * @author David Gilbert
 */
public class ArrowPanel extends JPanel {
  /** A constant for the up arrow. */
  public static final int UP = 0;
  /** A constant for the down arrow. */
  public static final int DOWN = 1;
  /** The arrow type. */
  private int type = UP;
  /** The available area. */
  private Rectangle2D available = new Rectangle2D.Float();
  /**
   * Creates a new arrow panel.
   * 
   * @param type
   *          the arrow type.
   */
  public ArrowPanel(final int type) {
    this.type = type;
    setPreferredSize(new Dimension(14, 9));
  }
  /**
   * Paints the arrow panel.
   * 
   * @param g
   *          the graphics device for drawing on.
   */
  public void paintComponent(final Graphics g) {
    super.paintComponent(g);
    final Graphics2D g2 = (Graphics2D) g;
    // first determine the size of the drawing area...
    final Dimension size = getSize();
    final Insets insets = getInsets();
    this.available.setRect(insets.left, insets.top, size.getWidth() - insets.left - insets.right,
        size.getHeight() - insets.top - insets.bottom);
    g2.translate(insets.left, insets.top);
    g2.fill(getArrow(this.type));
  }
  /**
   * Returns a shape for the arrow.
   * 
   * @param t
   *          the arrow type.
   * 
   * @return the arrow shape.
   */
  private Shape getArrow(final int t) {
    switch (t) {
    case UP:
      return getUpArrow();
    case DOWN:
      return getDownArrow();
    default:
      return getUpArrow();
    }
  }
  /**
   * Returns an up arrow.
   * 
   * @return an up arrow.
   */
  private Shape getUpArrow() {
    final Polygon result = new Polygon();
    result.addPoint(7, 2);
    result.addPoint(2, 7);
    result.addPoint(12, 7);
    return result;
  }
  /**
   * Returns a down arrow.
   * 
   * @return a down arrow.
   */
  private Shape getDownArrow() {
    final Polygon result = new Polygon();
    result.addPoint(7, 7);
    result.addPoint(2, 2);
    result.addPoint(12, 2);
    return result;
  }
}





A JPanel with a textured background.

/*
 *  TexturedPanel.java
 *  2006-11-02
 */
//cb.aloe.decor;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Insets;
import java.awt.Paint;
import java.awt.Rectangle;
import java.awt.TexturePaint;
import java.awt.image.BufferedImage;
import javax.swing.Icon;
import javax.swing.JPanel;
/**
 * A JPanel with a textured background.
 * 
 * @author Christopher Bach
 */
public class TexturedPanel extends JPanel {
  private TexturePaint ourPainter = null;
  private Color ourDefaultForeground = Color.white;
  private Color ourDefaultBackground = Color.gray;
  /**
   * Creates a new TexturedPanel with a simple striped pattern.
   */
  public TexturedPanel() {
    super();
    ourDefaultForeground = Color.white;
    ourDefaultBackground = getBackground();
    setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Creates a new TexturedPanel with a simple striped pattern consisting of the
   * given foreground and background colors.
   */
  public TexturedPanel(Color foreground, Color background) {
    super();
    ourDefaultForeground = (foreground != null ? foreground : Color.white);
    ourDefaultBackground = (background != null ? background : getBackground());
    setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Creates a new TexturedPanel with a simple pattern based on the provided
   * texture map and consisting of the given foreground and background colors.
   */
  public TexturedPanel(Color foreground, Color background, boolean[][] texture) {
    super();
    ourDefaultForeground = (foreground != null ? foreground : Color.white);
    ourDefaultBackground = (background != null ? background : getBackground());
    setupTexturePainter(ourDefaultForeground, ourDefaultBackground, texture, 1);
  }
  /**
   * Creates a new TexturedPanel with a simple pattern based on the provided
   * texture map and consisting of the given foreground and background colors.
   */
  public TexturedPanel(Color foreground, Color background, boolean[][] texture, int scale) {
    super();
    ourDefaultForeground = (foreground != null ? foreground : Color.white);
    ourDefaultBackground = (background != null ? background : getBackground());
    setupTexturePainter(ourDefaultForeground, ourDefaultBackground, texture, scale);
  }
  /**
   * Creates a new TexturedPanel that tiles the provided image.
   */
  public TexturedPanel(Image texture) {
    super();
    ourDefaultForeground = Color.white;
    ourDefaultBackground = getBackground();
    if (texture != null)
      setupImagePainter(texture);
    else
      setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Creates a new TexturedPanel that tiles the provided icon.
   */
  public TexturedPanel(Icon textureIcon) {
    super();
    ourDefaultForeground = Color.white;
    ourDefaultBackground = getBackground();
    if (textureIcon != null) {
      setupIconPainter(textureIcon);
    }
    else
      setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Sets up this TexturedPanel to paint a simple background based on the
   * provided texture and consisting of the provided colors.
   */
  public void setTexture(Color foreground, Color background, boolean[][] texture) {
    if (foreground != null && background != null && texture != null && texture.length > 0
        && texture[0].length > 0) {
      setupTexturePainter(foreground, background, texture, 1);
    }
  }
  /**
   * 
   */
  public void setTexture(Color foreground, Color background, boolean[][] texture, int scale) {
    setupTexturePainter(foreground, background, texture, scale);
  }
  /**
   * Sets up this TexturedPanel to paint a striped background consisting of the
   * provided colors.
   */
  public void setTextureColors(Color foreground, Color background) {
    if (foreground != null && background != null) {
      ourDefaultForeground = foreground;
      ourDefaultBackground = background;
      setupDefaultPainter(foreground, background);
    }
  }
  /**
   * Sets up this TexturedPanel to paint a tiled background consisting of the
   * provided image. If the image is null, the background will revert to a
   * striped texture consisting of the last known colors.
   */
  public void setTextureImage(Image texture) {
    if (texture != null)
      setupImagePainter(texture);
    else
      setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Sets up this TexturedPanel to paint a tiled background consisting of the
   * provided icon. If the icon is null, the background will revert to a striped
   * texture consisting of the last known colors.
   */
  public void setTextureIcon(Icon textureIcon) {
    if (textureIcon != null) {
      setupIconPainter(textureIcon);
    }
    else
      setupDefaultPainter(ourDefaultForeground, ourDefaultBackground);
  }
  /**
   * Returns the image buffer used by this TexturedPanel"s painter.
   */
  public Image getTexture() {
    if (ourPainter == null)
      return null;
    else
      return ourPainter.getImage();
  }
  /**
   * Creates a new TexturePaint using the provided colors.
   */
  private void setupDefaultPainter(Color foreground, Color background) {
    if (foreground == null || background == null) {
      ourPainter = null;
      return;
    }
    BufferedImage buff = new BufferedImage(6, 6, BufferedImage.TYPE_INT_ARGB_PRE);
    Graphics2D g2 = buff.createGraphics();
    g2.setColor(background);
    g2.fillRect(0, 0, 6, 6);
    g2.setColor(foreground);
    g2.drawLine(0, 2, 6, 2);
    g2.drawLine(0, 5, 6, 5);
    ourPainter = new TexturePaint(buff, new Rectangle(0, 0, 6, 6));
    g2.dispose();
  }
  /**
   * Creates a new TexturePaint using the provided colors and texture map.
   */
  private void setupTexturePainter(Color foreground, Color background, boolean[][] texture,
      int scale) {
    if (texture == null || texture.length < 1 || texture[0].length < 1) {
      setupDefaultPainter(foreground, background);
      return;
    }
    else if (foreground == null || background == null) {
      ourPainter = null;
      return;
    }
    scale = Math.max(1, scale);
    int w = texture[0].length;
    int h = texture.length;
    BufferedImage buff = new BufferedImage(w * scale, h * scale, BufferedImage.TYPE_INT_ARGB_PRE);
    Graphics2D g2 = buff.createGraphics();
    g2.setColor(background);
    g2.fillRect(0, 0, w * scale, h * scale);
    g2.setColor(foreground);
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        try {
          if (texture[i][j])
            g2.fillRect(j * scale, i * scale, scale, scale);
        }
        // g2.drawLine(j, i, j, i); }
        catch (ArrayIndexOutOfBoundsException aob) {
        }
      }
    }
    ourPainter = new TexturePaint(buff, new Rectangle(0, 0, w * scale, h * scale));
    g2.dispose();
  }
  /**
   * Creates a new TexturePaint using the provided image.
   */
  private void setupImagePainter(Image texture) {
    if (texture == null) {
      ourPainter = null;
      return;
    }
    int w = texture.getWidth(this);
    int h = texture.getHeight(this);
    if (w <= 0 || h <= 0) {
      ourPainter = null;
      return;
    }
    BufferedImage buff = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB_PRE);
    Graphics2D g2 = buff.createGraphics();
    g2.drawImage(texture, 0, 0, this);
    ourPainter = new TexturePaint(buff, new Rectangle(0, 0, w, h));
    g2.dispose();
  }
  /**
   * Creates a new TexturePaint using the provided icon.
   */
  private void setupIconPainter(Icon texture) {
    if (texture == null) {
      ourPainter = null;
      return;
    }
    int w = texture.getIconWidth();
    int h = texture.getIconHeight();
    if (w <= 0 || h <= 0) {
      ourPainter = null;
      return;
    }
    BufferedImage buff = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB_PRE);
    Graphics2D g2 = buff.createGraphics();
    texture.paintIcon(this, g2, 0, 0);
    ourPainter = new TexturePaint(buff, new Rectangle(0, 0, w, h));
    g2.dispose();
  }
  /**
   * Paints this component with its textured background.
   */
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (ourPainter != null) {
      int w = getWidth();
      int h = getHeight();
      Insets in = getInsets();
      int x = in.left;
      int y = in.top;
      w = w - in.left - in.right;
      h = h - in.top - in.bottom;
      if (w >= 0 && h >= 0) {
        Graphics2D g2 = (Graphics2D) g;
        Paint pt = g2.getPaint();
        g2.setPaint(ourPainter);
        g2.fillRect(x, y, w, h);
        g2.setPaint(pt);
      }
    }
  }
}





A panel that allows the user to select a date.

/* 
 * 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);
    }
}





Customizing JPanel Look and Feel

Property StringObject TypePanel.backgroundColorPanel.borderBorderPanel.fontFontPanel.foregroundColorPanelUIString


Gradient Panel

/*
 *  soapUI, copyright (C) 2004-2009 eviware.ru 
 *
 *  soapUI is free software; you can redistribute it and/or modify it under the 
 *  terms of version 2.1 of the GNU Lesser General Public License as published by 
 *  the Free Software Foundation.
 *
 *  soapUI 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 at gnu.org.
 */

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LayoutManager;
import java.awt.Paint;
import javax.swing.JPanel;
/**
 * Created by IntelliJ IDEA.
 */
public class GradientPanel extends JPanel
{
  // ------------------------------ FIELDS ------------------------------
  public final static int HORIZONTAL = 0;
  public final static int VERTICAL = 1;
  public final static int DIAGONAL_LEFT = 2;
  public final static int DIAGONAL_RIGHT = 3;
  private int direction = HORIZONTAL;
  private boolean cyclic;
  private int maxLength;
  // --------------------------- CONSTRUCTORS ---------------------------
  public GradientPanel()
  {
    this( HORIZONTAL );
  }
  public GradientPanel( int direction )
  {
    super( new BorderLayout() );
    setOpaque( false );
    this.direction = direction;
  }
  public GradientPanel( LayoutManager layoutManager )
  {
    super( layoutManager );
    setOpaque( false );
    this.direction = HORIZONTAL;
  }
  // --------------------- GETTER / SETTER METHODS ---------------------
  public int getDirection()
  {
    return direction;
  }
  public void setDirection( int direction )
  {
    this.direction = direction;
  }
  public boolean isCyclic()
  {
    return cyclic;
  }
  public void setCyclic( boolean cyclic )
  {
    this.cyclic = cyclic;
  }
  public void setMaxLength( int maxLength )
  {
    this.maxLength = maxLength;
  }
  // -------------------------- OTHER METHODS --------------------------
  public void paintComponent( Graphics g )
  {
    if( isOpaque() )
    {
      super.paintComponent( g );
      return;
    }
    int width = getWidth();
    int height = getHeight();
    // Create the gradient paint
    GradientPaint paint = null;
    Color sc = getForeground();
    Color ec = getBackground();
    switch( direction )
    {
    case HORIZONTAL :
    {
      paint = new GradientPaint( 0, height / 2, sc, width, height / 2, ec, cyclic );
      break;
    }
    case VERTICAL :
    {
      paint = new GradientPaint( width / 2, 0, sc, width / 2, maxLength > 0 ? maxLength : height, ec, cyclic );
      break;
    }
    case DIAGONAL_LEFT :
    {
      paint = new GradientPaint( 0, 0, sc, width, height, ec, cyclic );
      break;
    }
    case DIAGONAL_RIGHT :
    {
      paint = new GradientPaint( width, 0, sc, 0, height, ec, cyclic );
      break;
    }
    }
    if( paint == null )
    {
      throw new RuntimeException( "Invalid direction specified in GradientPanel" );
    }
    // we need to cast to Graphics2D for this operation
    Graphics2D g2d = ( Graphics2D )g;
    // save the old paint
    Paint oldPaint = g2d.getPaint();
    // set the paint to use for this operation
    g2d.setPaint( paint );
    // fill the background using the paint
    g2d.fillRect( 0, 0, width, height );
    // restore the original paint
    g2d.setPaint( oldPaint );
    super.paintComponent( g );
  }
}





Subclass JPanel

import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class OvalPanel extends JPanel {
  Color color;
  public OvalPanel() {
    this(Color.black);
  }
  public OvalPanel(Color color) {
    this.color = color;
  }
  public void paintComponent(Graphics g) {
    int width = getWidth();
    int height = getHeight();
    g.setColor(color);
    g.drawOval(0, 0, width, height);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new GridLayout(2, 2));
    Color colors[] = { Color.RED, Color.BLUE, Color.GREEN, Color.YELLOW };
    for (int i = 0; i < 4; i++) {
      OvalPanel panel = new OvalPanel(colors[i]);
      panel.add(new JButton("asdf"));
      frame.add(panel);
    }
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}





Using JPanel as a canvas

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class OvalPanelCanvas extends JPanel {
  public OvalPanelCanvas() {
  }
  public void paintComponent(Graphics g) {
    int width = getWidth();
    int height = getHeight();
    g.setColor(Color.black);
    g.drawOval(0, 0, width, height);
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new OvalPanelCanvas());
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}





Using JPanel as a container

JPanel components are opaque, while JComponents are not opaque



import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PanelWithComponents {
  public static void main(String[] a) {
    JPanel panel = new JPanel();
    JButton okButton = new JButton("OK");
    panel.add(okButton);
    JButton cancelButton = new JButton("Cancel");
    panel.add(cancelButton);
    JFrame frame = new JFrame("Oval Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(panel);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}