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From "Ross Laidlaw (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SIS-49) ArrayIndexOutOfBoundsException caused by method getCircularRegionApproximation(int numberOfPoints) in LatLonPointRadius class
Date Thu, 05 Jul 2012 00:22:34 GMT
Ross Laidlaw created SIS-49:
-------------------------------

             Summary: ArrayIndexOutOfBoundsException caused by method getCircularRegionApproximation(int
numberOfPoints) in LatLonPointRadius class
                 Key: SIS-49
                 URL: https://issues.apache.org/jira/browse/SIS-49
             Project: Spatial Information Systems
          Issue Type: Bug
          Components: geometry objects
            Reporter: Ross Laidlaw
            Priority: Minor
             Fix For: 0.3-incubating


The method public LatLon[] getCircularRegionApproximation(int numberOfPoints) throws an ArrayIndexOutOfBoundsException
under certain conditions.  This is because of an error in the following loop:

{code}
LatLon[] points = new LatLon[numberOfPoints + 1];
for (int i = 0; i < 360; i += (360 / numberOfPoints)) 
{
  points[i] = DistanceUtils.getPointOnGreatCircle(this.center.getLat(),
      this.center.getLon(), radius, i);
}
{code}

The exception arises because integer i is used as the array index for the points array, but
the value of i jumps up by (360/numberOfPoints) on every iteration of the loop.  For example,
if numberOfPoints is 10, then i will increase by 36 each time, resulting in the exception.
 The points array size is set before the loop to 'numberOfPoints + 1'.

As an experiment, I changed the loop as shown below and this appeared to fix the problem.
 There may be a more elegant solution:

{code}
LatLon[] points = new LatLon[numberOfPoints + 1];
for (int i = 0, j = 0; i < 360; i += (360 / numberOfPoints), j++) 
{
  points[j] = DistanceUtils.getPointOnGreatCircle(this.center.getLat(),
      this.center.getLon(), radius, i);
}
{code}

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