RE: Problems (NullPointer or ArrayIndex) if no d ata available for barchart

I agree with Tamer that a validation would be a very nice thing indeed to
have. When systems get connected together, the presentation system is not in
control of the data. Introducing a check would imho have a minimal
performance overhead.

Best regards,
Fredrik

-----Original Message-----
From: Nathaniel G. Auvil [mailto:[email protected]] 
Sent: 27. februar 2004 15:02
To: [email protected]
Subject: RE: [jCharts-users] Problems (NullPointer or ArrayIndex) if no data
available for barchart



Well, i guess the decision was why would someone try to plot a null dataset?
I am not sure this is something that happens very often so I would like to
avoid the overhead and code of a validation.


--- [email protected] wrote:
> providing a placeholder image is exactly how we solved this issue.
> 
> 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: [email protected]
> [mailto:[email protected]]On Behalf Of 
> Nathaniel G. Auvil
> Sent: Freitag, 27. Februar 2004 01:29
> To: [email protected]
> 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.
> 
> 
> 
> 
> --- [email protected] wrote:
> > hi all
> > 
> > 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:
> > 
> > I'm using jcharts 0.7.4 (the posted methods are the same in 0.7.5)
> > 
> > - legendlabels and data array (double[][]) are null
> > 
> > java.lang.NullPointerException
> > 	at
org.jCharts.chartData.AxisChartDataSet.getNumberOfDataSets(AxisChartDataSet.
java:136)
> > 	at 
> > org.jCharts.chartData.AxisDataSeries.addIAxisPlotDataSet(AxisDataSer
> > ies.java:166)
> > 
> > code which throws exception [AxisChartDataSet.getNumberOfDataSets]:
> > 	public final int getNumberOfDataSets()
> > 	{
> > 		return this.data.length;
> > 	}
> > 
> > - legenlabels is null, data array is new double[0][0];
> > 
> > java.lang.ArrayIndexOutOfBoundsException: 0
> > 	at
org.jCharts.chartData.DataSet.getNumberOfDataItems(DataSet.java:148)
> > 	at 
> > org.jCharts.chartData.AxisDataSeries.addIAxisPlotDataSet(AxisDataSer
> > ies.java:168)
> > 
> > code which throws exception [DataSet.getNumberOfDataItems]:
> > 	public int getNumberOfDataItems()
> > 	{
> > 		return this.data[ 0 ].length;
> > 	}
> > 
> > is there any reason, why null and/or length is not checked in those 
> > methods ??
> > 
> > is there any other way to get a empty chart, I do set
> > setUserDefinedScale(0, 2)
> > setNumItems(5)
> > 
> > 
> > regards
> > 
> > tamer
> > 
> > 
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