# Series.java

    /* ===========================================================
     * JFreeChart : a free chart library for the Java(tm) platform
     * ===========================================================
     *
     * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
     *
     * Project Info:  http://www.jfree.org/jfreechart/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.]
     *
     * -----------
     * Series.java
     * -----------
     * (C) Copyright 2001-2007, by Object Refinery Limited.
     *
     * Original Author:  David Gilbert (for Object Refinery Limited);
     * Contributor(s):   -;
     *
     * Changes
     * -------
     * 15-Nov-2001 : Version 1 (DG);
     * 29-Nov-2001 : Added cloning and property change support (DG);
     * 30-Jan-2002 : Added a description attribute and changed the constructors to
     *               protected (DG);
     * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG);
     * 13-Mar-2003 : Implemented Serializable (DG);
     * 01-May-2003 : Added equals() method (DG);
     * 26-Jun-2003 : Changed listener list to use EventListenerList - see bug
     *               757027 (DG);
     * 15-Oct-2003 : Added a flag to control whether or not change events are sent
     *               to registered listeners (DG);
     * 19-May-2005 : Made abstract (DG);
     * ------------- JFREECHART 1.0.x ---------------------------------------------
     * 04-May-2006 : Updated API docs (DG);
     * 26-Sep-2007 : Added isEmpty() and getItemCount() methods (DG);
     *
     */

    package org.jfree.data.general;

    import java.beans.PropertyChangeListener;
    import java.beans.PropertyChangeSupport;
    import java.io.Serializable;

    import javax.swing.event.EventListenerList;

    import org.jfree.util.ObjectUtilities;

    /**
     * Base class representing a data series.  Subclasses are left to implement the
     * actual data structures.
     * <P>
     * The series has two properties ("Key" and "Description") for which you can
     * register a <code>PropertyChangeListener</code>.
     * <P>
     * You can also register a {@link SeriesChangeListener} to receive notification
     * of changes to the series data.
     */
    public abstract class Series implements Cloneable, Serializable {

        /** For serialization. */
        private static final long serialVersionUID = -6906561437538683581L;

        /** The key for the series. */
        private Comparable key;

        /** A description of the series. */
        private String description;

        /** Storage for registered change listeners. */
        private EventListenerList listeners;

        /** Object to support property change notification. */
        private PropertyChangeSupport propertyChangeSupport;

        /** A flag that controls whether or not changes are notified. */
        private boolean notify;

        /**
         * Creates a new series with the specified key.
         *
         * @param key  the series key (<code>null</code> not permitted).
         */
        protected Series(Comparable key) {
            this(key, null);
        }

        /**
         * Creates a new series with the specified key and description.
         *
         * @param key  the series key (<code>null</code> NOT permitted).
         * @param description  the series description (<code>null</code> permitted).
         */
        protected Series(Comparable key, String description) {
            if (key == null) {
                throw new IllegalArgumentException("Null 'key' argument.");
            }
            this.key = key;
            this.description = description;
            this.listeners = new EventListenerList();
            this.propertyChangeSupport = new PropertyChangeSupport(this);
            this.notify = true;
        }

        /**
         * Returns the key for the series.
         *
         * @return The series key (never <code>null</code>).
         *
         * @see #setKey(Comparable)
         */
        public Comparable getKey() {
            return this.key;
        }

        /**
         * Sets the key for the series and sends a <code>PropertyChangeEvent</code>
         * (with the property name "Key") to all registered listeners.
         *
         * @param key  the key (<code>null</code> not permitted).
         *
         * @see #getKey()
         */
        public void setKey(Comparable key) {
            if (key == null) {
                throw new IllegalArgumentException("Null 'key' argument.");
            }
            Comparable old = this.key;
            this.key = key;
            this.propertyChangeSupport.firePropertyChange("Key", old, key);
        }

        /**
         * Returns a description of the series.
         *
         * @return The series description (possibly <code>null</code>).
         *
         * @see #setDescription(String)
         */
        public String getDescription() {
            return this.description;
        }

        /**
         * Sets the description of the series and sends a
         * <code>PropertyChangeEvent</code> to all registered listeners.
         *
         * @param description  the description (<code>null</code> permitted).
         *
         * @see #getDescription()
         */
        public void setDescription(String description) {
            String old = this.description;
            this.description = description;
            this.propertyChangeSupport.firePropertyChange("Description", old,
                    description);
        }

        /**
         * Returns the flag that controls whether or not change events are sent to
         * registered listeners.
         *
         * @return A boolean.
         *
         * @see #setNotify(boolean)
         */
        public boolean getNotify() {
            return this.notify;
        }

        /**
         * Sets the flag that controls whether or not change events are sent to
         * registered listeners.
         *
         * @param notify  the new value of the flag.
         *
         * @see #getNotify()
         */
        public void setNotify(boolean notify) {
            if (this.notify != notify) {
                this.notify = notify;
                fireSeriesChanged();
            }
        }

        /**
         * Returns <code>true</code> if the series contains no data items, and
         * <code>false</code> otherwise.
         *
         * @return A boolean.
         *
         * @since 1.0.7
         */
        public boolean isEmpty() {
            return (getItemCount() == 0);
        }

        /**
         * Returns the number of data items in the series.
         *
         * @return The number of data items in the series.
         */
        public abstract int getItemCount();

        /**
         * Returns a clone of the series.
         * <P>
         * Notes:
         * <ul>
         * <li>No need to clone the name or description, since String object is
         * immutable.</li>
         * <li>We set the listener list to empty, since the listeners did not
         * register with the clone.</li>
         * <li>Same applies to the PropertyChangeSupport instance.</li>
         * </ul>
         *
         * @return A clone of the series.
         *
         * @throws CloneNotSupportedException  not thrown by this class, but
         *         subclasses may differ.
         */
        public Object clone() throws CloneNotSupportedException {

            Series clone = (Series) super.clone();
            clone.listeners = new EventListenerList();
            clone.propertyChangeSupport = new PropertyChangeSupport(clone);
            return clone;

        }

        /**
         * Tests the series for equality with another object.
         *
         * @param obj  the object (<code>null</code> permitted).
         *
         * @return <code>true</code> or <code>false</code>.
         */
        public boolean equals(Object obj) {
            if (obj == this) {
                return true;
            }
            if (!(obj instanceof Series)) {
                return false;
            }
            Series that = (Series) obj;
            if (!getKey().equals(that.getKey())) {
                return false;
            }
            if (!ObjectUtilities.equal(getDescription(), that.getDescription())) {
                return false;
            }
            return true;
        }

        /**
         * Returns a hash code.
         *
         * @return A hash code.
         */
        public int hashCode() {
            int result;
            result = this.key.hashCode();
            result = 29 * result + (this.description != null
                    ? this.description.hashCode() : 0);
            return result;
        }

        /**
         * Registers an object with this series, to receive notification whenever
         * the series changes.
         * <P>
         * Objects being registered must implement the {@link SeriesChangeListener}
         * interface.
         *
         * @param listener  the listener to register.
         */
        public void addChangeListener(SeriesChangeListener listener) {
            this.listeners.add(SeriesChangeListener.class, listener);
        }

        /**
         * Deregisters an object, so that it not longer receives notification
         * whenever the series changes.
         *
         * @param listener  the listener to deregister.
         */
        public void removeChangeListener(SeriesChangeListener listener) {
            this.listeners.remove(SeriesChangeListener.class, listener);
        }

        /**
         * General method for signalling to registered listeners that the series
         * has been changed.
         */
        public void fireSeriesChanged() {
            if (this.notify) {
                notifyListeners(new SeriesChangeEvent(this));
            }
        }

        /**
         * Sends a change event to all registered listeners.
         *
         * @param event  contains information about the event that triggered the
         *               notification.
         */
        protected void notifyListeners(SeriesChangeEvent event) {

            Object[] listenerList = this.listeners.getListenerList();
            for (int i = listenerList.length - 2; i >= 0; i -= 2) {
                if (listenerList[i] == SeriesChangeListener.class) {
                    ((SeriesChangeListener) listenerList[i + 1]).seriesChanged(
                            event);
                }
            }

        }

        /**
         * Adds a property change listener to the series.
         *
         * @param listener  the listener.
         */
        public void addPropertyChangeListener(PropertyChangeListener listener) {
            this.propertyChangeSupport.addPropertyChangeListener(listener);
        }

        /**
         * Removes a property change listener from the series.
         *
         * @param listener The listener.
         */
        public void removePropertyChangeListener(PropertyChangeListener listener) {
            this.propertyChangeSupport.removePropertyChangeListener(listener);
        }

        /**
         * Fires a property change event.
         *
         * @param property  the property key.
         * @param oldValue  the old value.
         * @param newValue  the new value.
         */
        protected void firePropertyChange(String property, Object oldValue,
                Object newValue) {
            this.propertyChangeSupport.firePropertyChange(property, oldValue,
                    newValue);
        }

    }