wkt-wickedcharts: NPE when invalid data is provided

[danhaywood]

from isisaddons-legacy/isis-wicket-wickedcharts#2

With the current Java Math demo data in the KitchenSink application trying to show a summarychart leads to the following exception:

Caused by: java.lang.NullPointerException
    at java.math.BigDecimal.compareTo(BigDecimal.java:2554)
    at java.math.BigDecimal.min(BigDecimal.java:2665)
    at org.isisaddons.wicket.wickedcharts.cpt.ui.summarychart.CollectionContentsAsSummaryChart.minOf(CollectionContentsAsSummaryChart.java:163)
    at org.isisaddons.wicket.wickedcharts.cpt.ui.summarychart.CollectionContentsAsSummaryChart.createChartValue(CollectionContentsAsSummaryChart.java:119)
    at org.isisaddons.wicket.wickedcharts.cpt.ui.summarychart.CollectionContentsAsSummaryChart.buildGui(CollectionContentsAsSummaryChart.java:101)
    at org.isisaddons.wicket.wickedcharts.cpt.ui.summarychart.CollectionContentsAsSummaryChart.onModelChanged(CollectionContentsAsSummaryChart.java:168)

[danhaywood]

martin-g:

I use the following fix locally to avoid the NPE. Not sure it is the correct one though

     private BigDecimal maxOf(BigDecimal max, final BigDecimal summaryMax) {
-        return max != null ? max.max(summaryMax) : summaryMax;
+        return max != null
+            ? summaryMax != null
+                ? max.max(summaryMax)
+                : max
+            : BigDecimal.ZERO;
     }

     private BigDecimal minOf(BigDecimal min, final BigDecimal summaryMin) {
-        return min != null ? min.min(summaryMin) : summaryMin;
+        return min != null
+            ? summaryMin != null
+                ? min.min(summaryMin)
+                : min
+            : BigDecimal.ZERO;
     }

[danhaywood]

danhaywood:

possibly not; what if every value is null? The result ought to be null,
but I think this code might give BigDecimal.ZERO.

On 9 October 2014 09:02, Martin Grigorov notifications@github.com wrote:

I use the following fix locally to avoid the NPE. Not sure it is the
correct one though

 private BigDecimal maxOf(BigDecimal max, final BigDecimal summaryMax) {-        return max != null ? max.max(summaryMax) : summaryMax;+        return max != null+            ? summaryMax != null+                ? max.max(summaryMax)+                : max+            : BigDecimal.ZERO;
 }

 private BigDecimal minOf(BigDecimal min, final BigDecimal summaryMin) {-        return min != null ? min.min(summaryMin) : summaryMin;+        return min != null+            ? summaryMin != null+                ? min.min(summaryMin)+                : min+            : BigDecimal.ZERO;
 }

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[danhaywood]

martin-g:

returning null instead of BigDecimal.ZERO seems to do the job as well