--- a/gnv-artifacts/src/main/java/de/intevation/gnv/chart/DefaultHistogram.java	Tue Mar 23 14:11:51 2010 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/chart/DefaultHistogram.java	Wed Mar 24 14:48:55 2010 +0000
@@ -14,25 +14,73 @@
 import org.jfree.data.statistics.HistogramDataset;
 
 /**
- * @author Ingo Weinzierl (ingo.weinzierl@intevation.de)
+ * Default implementation of {@link de.intevation.gnv.chart.AbstractHistogram}.
+ *
+ * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
  */
 public class DefaultHistogram
 extends      AbstractHistogram
 {
-    // TODO take a better default value
+    /**
+     * Default bin count.
+     * TODO find a better default value
+     */
     public static final int DEFAULT_BINS = 15;
+
+    /**
+     * Constant field for limitating the number of bin in a single histogram.
+     */
     public static final int MAXIMAL_BINS = 20;
+
+    /**
+     * Default key to retrieve the number of bins from {@link
+     * #requestParameter}.
+     */
     public static final String REQUEST_KEY_BIN_COUNT   = "bincount";
+
+    /**
+     * Default key to retrieve the width of a single bin from {@link
+     * #requestParameter}.
+     */
     public static final String REQUEST_KEY_BIN_WIDTH   = "binwidth";
+
+    /**
+     * Default key to retrieve the chart width from {@link #requestParameter}.
+     */
     public static final String REQUEST_KEY_CHART_WIDTH = "width";
+
+    /**
+     * Default key to retrieve the <code>Locale</code> object from {@link
+     * #requestParameter} used for i18n support.
+     */
     public static final String REQUEST_KEY_LOCALE      = "locale";
+
+    /**
+     * Default key to retrieve the object from {@link #requestParameter}. It 
+     * defines which value this chart has to be used for bin calculation. You
+     * can either adjust the number of bins or the width of a single bin.
+     */
     public static final String REQUEST_KEY_BIN_CHOICE  = "bintype";
 
+    /**
+     * Logger used for logging with log4j.
+     */
     private static Logger logger = Logger.getLogger(DefaultHistogram.class);
 
+    /**
+     * Object storing some further parameter used for chart settings.
+     */
     protected Map requestParameter;
 
 
+    /**
+     * Constructor to create DefaultHistogram objects.
+     *
+     * @param labels Labels to decorate this chart.
+     * @param data Raw data to be displayed in histogram.
+     * @param theme Theme used to adjust the chart look.
+     * @param requestParameter Object which serves some further settings.
+     */
     public DefaultHistogram(
         ChartLabels labels, Object[] data, ChartTheme theme, Map requestParameter
     ) {
@@ -41,6 +89,10 @@
     }
 
 
+    /**
+     * @see de.intevation.gnv.chart.AbstractHistogram#applyDatasets()
+     */
+    @Override
     protected void applyDatasets() {
         XYPlot plot = (XYPlot) chart.getPlot();
 
@@ -56,6 +108,15 @@
     }
 
 
+    /**
+     * Method which scans the hole bunch of values and returns an array with
+     * contains min and max value. Min value is stored at position 0, max value
+     * is stored at position 1 in that array.
+     *
+     * @param values Array which contains all values
+     *
+     * @return Array which contains min and max value
+     */
     protected double[] getMinMax(double[] values) {
         double[] minmax = new double[2];
         minmax[0] = Double.MAX_VALUE;
@@ -71,6 +132,13 @@
     }
 
 
+    /**
+     * Turn a Double[] into a double[].
+     *
+     * @param array Doube[]
+     *
+     * @return double[]
+     */
     protected double[] toDouble(Double[] array) {
         int length      = array.length;
         double[] values = new double[length];
@@ -83,6 +151,16 @@
     }
 
 
+    /**
+     * Method to calculate the number of bins this chart should be parted into.
+     * The real calculation takes place in {@link #getBinCountByNumber} and
+     * {@link #getBinCountByWidth}. This method switches between these methods
+     * depending on the object stored in {@link #requestParameter}.
+     *
+     * @param values All values used in this histogram
+     *
+     * @return Number of bins
+     */
     protected int getBinCount(double[] values) {
         String param = (String) requestParameter.get(REQUEST_KEY_BIN_CHOICE);
 
@@ -95,6 +173,16 @@
     }
 
 
+    /**
+     * Method to retrieve the number of bins. If {@link #requestParameter}
+     * contains a valid <code>Integer</code> at
+     * <code>REQUEST_KEY_BIN_COUNT</code> and this is smaller than or equal 
+     * {@link #MAXIMAL_BINS}, this value is used. If no valid
+     * <code>Integer</code> is given or if the value in {@link #requestParameter}
+     * is bigger than {@link #MAXIMAL_BINS}, {@link #DEFAULT_BINS} is used.
+     *
+     * @return Number of bins
+     */
     protected int getBinCountByNumber() {
         int    bins  = -1;
         String param = (String) requestParameter.get(REQUEST_KEY_BIN_COUNT);
@@ -115,6 +203,14 @@
     }
 
 
+    /**
+     * Serves the number of bins depending on a given width for each bin, but
+     * maximum bin count is limited by {@link MAXIMAL_BINS}.
+     *
+     * @param values All values in this histogram
+     *
+     * @return Number of bins
+     */
     protected int getBinCountByWidth(double[] values) {
         int    bins   = -1;
         String param  = (String) requestParameter.get(REQUEST_KEY_BIN_WIDTH);