RE: [jCharts-users] Problems (NullPointer or ArrayIndex) if no data available for barchart

[<tam...@ub...>]

providing a placeholder image is exactly how we solved this issue.=20

still I was wondering, whether the cart implementation couldn't handle =
that. or let's say I was surprised it didn't catch that scenario and =
throw at least some validation exception instead of running into =
nullpointer.


-----Original Message-----
From: jch...@li...
[mailto:jch...@li...]On Behalf Of Nathaniel
G. Auvil
Sent: Freitag, 27. Februar 2004 01:29
To: jch...@li...
Subject: Re: [jCharts-users] Problems (NullPointer or ArrayIndex) if no
data available for barchart



If there is no data what do you expect to see in a chart?  What would be =
on the y-axis if there
are no data elements?

I would think your logic, would see there was no data, and stream a =
placeholder image instead of
the chart or a chart with a few zero values and labels of empty Strings.




--- tam...@ub... wrote:
> hi all
>=20
> we are generating clusteredbarcharts based on the result of some =
database selects, so the data
> to display is not static.
> we have a problem if there is no data. I have tried different ways to =
tweak this issue, but
> always ran into troubles:
>=20
> I'm using jcharts 0.7.4 (the posted methods are the same in 0.7.5)=20
>=20
> - legendlabels and data array (double[][]) are null=20
>=20
> java.lang.NullPointerException
> 	at =
org.jCharts.chartData.AxisChartDataSet.getNumberOfDataSets(AxisChartDataS=
et.java:136)
> 	at =
org.jCharts.chartData.AxisDataSeries.addIAxisPlotDataSet(AxisDataSeries.j=
ava:166)
>=20
> code which throws exception [AxisChartDataSet.getNumberOfDataSets]:
> 	public final int getNumberOfDataSets()
> 	{
> 		return this.data.length;
> 	}
>=20
> - legenlabels is null, data array is new double[0][0];
>=20
> java.lang.ArrayIndexOutOfBoundsException: 0
> 	at =
org.jCharts.chartData.DataSet.getNumberOfDataItems(DataSet.java:148)
> 	at =
org.jCharts.chartData.AxisDataSeries.addIAxisPlotDataSet(AxisDataSeries.j=
ava:168)
>=20
> code which throws exception [DataSet.getNumberOfDataItems]:
> 	public int getNumberOfDataItems()
> 	{
> 		return this.data[ 0 ].length;
> 	}
>=20
> is there any reason, why null and/or length is not checked in those =
methods ??=20
>=20
> is there any other way to get a empty chart, I do set=20
> setUserDefinedScale(0, 2)
> setNumItems(5)
>=20
>=20
> regards
>=20
> tamer
>=20
>=20
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