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jfreechart example source code file (ItemHandler.java)

This example jfreechart source code file (ItemHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

categoryserieshandler, categoryserieshandler, comparable, defaulthandler, defaulthandler, item, itemhandler, number, piedatasethandler, piedatasethandler, sax, saxexception, string, string, valuehandler

The jfreechart ItemHandler.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, 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.]
 *
 * ----------------
 * ItemHandler.java
 * ----------------
 * (C) Copyright 2003-2008, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 23-Jan-2003 : Version 1 (DG);
 *
 */

package org.jfree.data.xml;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * A handler for reading key-value items.
 */
public class ItemHandler extends DefaultHandler implements DatasetTags {

    /** The root handler. */
    private RootHandler root;

    /** The parent handler (can be the same as root, but not always). */
    private DefaultHandler parent;

    /** The key. */
    private Comparable key;

    /** The value. */
    private Number value;

    /**
     * Creates a new item handler.
     *
     * @param root  the root handler.
     * @param parent  the parent handler.
     */
    public ItemHandler(RootHandler root, DefaultHandler parent) {
        this.root = root;
        this.parent = parent;
        this.key = null;
        this.value = null;
    }

    /**
     * Returns the key that has been read by the handler, or <code>null.
     *
     * @return The key.
     */
    public Comparable getKey() {
        return this.key;
    }

    /**
     * Sets the key.
     *
     * @param key  the key.
     */
    public void setKey(Comparable key) {
        this.key = key;
    }

    /**
     * Returns the key that has been read by the handler, or <code>null.
     *
     * @return The value.
     */
    public Number getValue() {
        return this.value;
    }

    /**
     * Sets the value.
     *
     * @param value  the value.
     */
    public void setValue(Number value) {
        this.value = value;
    }

    /**
     * The start of an element.
     *
     * @param namespaceURI  the namespace.
     * @param localName  the element name.
     * @param qName  the element name.
     * @param atts  the attributes.
     *
     * @throws SAXException for errors.
     */
    public void startElement(String namespaceURI,
                             String localName,
                             String qName,
                             Attributes atts) throws SAXException {

        if (qName.equals(ITEM_TAG)) {
            KeyHandler subhandler = new KeyHandler(this.root, this);
            this.root.pushSubHandler(subhandler);
        }
        else if (qName.equals(VALUE_TAG)) {
            ValueHandler subhandler = new ValueHandler(this.root, this);
            this.root.pushSubHandler(subhandler);
        }
        else {
            throw new SAXException(
                "Expected <Item> or ...found " + qName
            );
        }

    }

    /**
     * The end of an element.
     *
     * @param namespaceURI  the namespace.
     * @param localName  the element name.
     * @param qName  the element name.
     */
    public void endElement(String namespaceURI,
                           String localName,
                           String qName) {

        if (this.parent instanceof PieDatasetHandler) {
            PieDatasetHandler handler = (PieDatasetHandler) this.parent;
            handler.addItem(this.key, this.value);
            this.root.popSubHandler();
        }
        else if (this.parent instanceof CategorySeriesHandler) {
            CategorySeriesHandler handler = (CategorySeriesHandler) this.parent;
            handler.addItem(this.key, this.value);
            this.root.popSubHandler();
        }

    }

}

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