/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2011, 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.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * -----------------------------------
 * StandardXYSeriesLabelGenerator.java
 * -----------------------------------
 * (C) Copyright 2004-2008, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 16-Nov-2004 : Version 1 (DG);
 * ------------- JFREECHART 1.0.x ---------------------------------------------
 * 24-Nov-2006 : Fixed equals() method and updated API docs (DG);
 * 31-Mar-2008 : Added hashCode() method to appease FindBugs (DG);
 *
 */

package org.jfree.chart.labels;

import java.io.Serializable;
import java.text.MessageFormat;

import org.jfree.chart.HashUtilities;
import org.jfree.data.xy.XYDataset;
import org.jfree.util.PublicCloneable;

/**
 * A standard series label generator for plots that use data from
 * an {@link org.jfree.data.xy.XYDataset}.
 * <br><br>
 * This class implements <code>PublicCloneable</code> by mistake but we retain
 * this for the sake of backward compatibility.
 */
public class StandardXYSeriesLabelGenerator implements XYSeriesLabelGenerator,
        Cloneable, PublicCloneable, Serializable {

    /** For serialization. */
    private static final long serialVersionUID = 1916017081848400024L;

    /** The default item label format. */
    public static final String DEFAULT_LABEL_FORMAT = "{0}";

    /** The format pattern. */
    private String formatPattern;

    /**
     * Creates a default series label generator (uses
     * {@link #DEFAULT_LABEL_FORMAT}).
     */
    public StandardXYSeriesLabelGenerator() {
        this(DEFAULT_LABEL_FORMAT);
    }

    /**
     * Creates a new series label generator.
     *
     * @param format  the format pattern (<code>null</code> not permitted).
     */
    public StandardXYSeriesLabelGenerator(String format) {
        if (format == null) {
            throw new IllegalArgumentException("Null 'format' argument.");
        }
        this.formatPattern = format;
    }

    /**
     * Generates a label for the specified series.  This label will be
     * used for the chart legend.
     *
     * @param dataset  the dataset (<code>null</code> not permitted).
     * @param series  the series.
     *
     * @return A series label.
     */
    public String generateLabel(XYDataset dataset, int series) {
        if (dataset == null) {
            throw new IllegalArgumentException("Null 'dataset' argument.");
        }
        String label = MessageFormat.format(
            this.formatPattern, createItemArray(dataset, series)
        );
        return label;
    }

    /**
     * Creates the array of items that can be passed to the
     * {@link MessageFormat} class for creating labels.
     *
     * @param dataset  the dataset (<code>null</code> not permitted).
     * @param series  the series (zero-based index).
     *
     * @return The items (never <code>null</code>).
     */
    protected Object[] createItemArray(XYDataset dataset, int series) {
        Object[] result = new Object[1];
        result[0] = dataset.getSeriesKey(series).toString();
        return result;
    }

    /**
     * Returns an independent copy of the generator.  This is unnecessary,
     * because instances are immutable anyway, but we retain this
     * behaviour for backwards compatibility.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if cloning is not supported.
     */
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    /**
     * Tests this object for equality with an arbitrary object.
     *
     * @param obj  the other object (<code>null</code> permitted).
     *
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof StandardXYSeriesLabelGenerator)) {
            return false;
        }
        StandardXYSeriesLabelGenerator that
                = (StandardXYSeriesLabelGenerator) obj;
        if (!this.formatPattern.equals(that.formatPattern)) {
            return false;
        }
        return true;
    }

    /**
     * Returns a hash code for this instance.
     *
     * @return A hash code.
     */
    public int hashCode() {
        int result = 127;
        result = HashUtilities.hashCode(result, this.formatPattern);
        return result;
    }

}

@@ -214,17 +214,17 @@
 2000-201
-1
+3
 , by Obj
@@ -1387,18 +1387,18 @@
  2004-20
-08
+13
 , by Obj
@@ -1794,16 +1794,56 @@
  (DG);%0D%0A
+ * 03-Jul-2013 : Use ParamChecks (DG);%0D%0A
  *%0D%0A */%0D
@@ -1984,16 +1984,58 @@
 ities;%0D%0A
+import org.jfree.chart.util.ParamChecks;%0D%0A
 import o
@@ -3210,116 +3210,55 @@
     
-if (format == null) %7B%0D%0A            throw new IllegalArgumentException(%22Null 'format' argument.%22);%0D%0A        %7D
+ParamChecks.nullNotPermitted(format, %22format%22);
 %0D%0A  
@@ -3659,118 +3659,57 @@
     
-if (dataset == null) %7B%0D%0A            throw new IllegalArgumentException(%22Null 'dataset' argument.%22);%0D%0A        %7D
+ParamChecks.nullNotPermitted(dataset, %22dataset%22);
 %0D%0A  

Use ParamChecks class.