RTree knn ArrayIndexOutOfBoundsException

[cugwind]

if (distances.elementAt(k - 1) > query_radius) {
result_correct = false;

      //query_radius = distances.elementAt(k);//when shapes.size() == k  throw   ArrayIndexOutOfBoundsException

==>
if (shapes.size() == k) {
query_radius = distances.elementAt(k - 1) + 0.000001d;
} else {
query_radius = distances.elementAt(k);
}

    } else {
      result_correct = true;

}