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

    /**
     * Generates a label for the specified series.
     * 
     * @param dataset  the dataset (<code>null</code> not permitted).
     * @param series  the series.
     * 
     * @return A series label.
     */
    public String generateLabel(CategoryDataset 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(CategoryDataset dataset, int series) {
        Object[] result = new Object[1];
        result[0] = dataset.getRowKey(series).toString();
        return result;
    }

    /**
     * Returns an independent copy of the generator.
     * 
     * @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 StandardCategorySeriesLabelGenerator)) {
            return false;
        }
        StandardCategorySeriesLabelGenerator that 
                = (StandardCategorySeriesLabelGenerator) 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;