XYItemKey.java

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2022, by David Gilbert 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.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * --------------
 * XYItemKey.java
 * --------------
 * (C) Copyright 2014-2022, by David Gilbert.
 *
 * Original Author:  David Gilbert;
 * Contributor(s):   -;
 *
 */

package org.jfree.data.xy;

import java.io.Serializable;
import java.util.Objects;

import org.jfree.chart.internal.Args;
import org.jfree.data.ItemKey;

/**
 * An object that references one data item in an {@link XYZDataset}.  This is 
 * used internally to track the data item that a 3D object is related to, if
 * any (and later that link is used for chart interaction).  Instances of
 * this class are immutable.
 * 
 * @param <S> the series key type.
 */
public class XYItemKey<S extends Comparable<S>> implements ItemKey, 
        Comparable<XYItemKey<S>>, Serializable {
    
    /** A key identifying a series in the dataset. */
    private final S seriesKey;
    
    /** The index of an item within a series. */
    private final int itemIndex;
    
    /**
     * Creates a new instance.
     * 
     * @param seriesKey  the series key.
     * @param itemIndex  the item index.
     */
    public XYItemKey(S seriesKey, int itemIndex) {
        Args.nullNotPermitted(seriesKey, "seriesKey");
        this.seriesKey = seriesKey;
        this.itemIndex = itemIndex;
    }
    
    /**
     * Returns the series key.
     * 
     * @return The series key (never {@code null}). 
     */
    public S getSeriesKey() {
        return this.seriesKey;
    }
    
    /**
     * Returns the item index.
     * 
     * @return The item index.
     */
    public int getItemIndex() {
        return this.itemIndex;
    }
    
    /**
     * Tests this instance for equality with an arbitrary object.
     * 
     * @param obj  the object to test ({@code null} permitted).
     * 
     * @return A boolean. 
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof XYItemKey)) {
            return false;
        }
        XYItemKey that = (XYItemKey) obj;
        if (!this.seriesKey.equals(that.seriesKey)) {
            return false;
        }
        if (this.itemIndex != that.itemIndex) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 41 * hash + Objects.hashCode(this.seriesKey);
        hash = 41 * hash + this.itemIndex;
        return hash;
    }

    @Override
    public String toJSONString() {
        StringBuilder sb = new StringBuilder();
        sb.append("{\"seriesKey\": \"").append(this.seriesKey.toString());
        sb.append("\", ");
        sb.append("\"itemIndex\": ").append(this.itemIndex).append("}");
        return sb.toString();
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("XYItemKey[seriesKey=");
        sb.append(this.seriesKey.toString()).append(",item=");
        sb.append(itemIndex);
        sb.append("]");
        return sb.toString();
    }

    @Override
    public int compareTo(XYItemKey<S> key) {
        int result = this.seriesKey.compareTo(key.seriesKey);
        if (result == 0) {
            result = this.itemIndex - key.itemIndex;
        }
        return result;
    }

}