Re: [Jts-topo-suite-user] IllegalArgumentException: Comparison method violates its general contract
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Re: [Jts-topo-suite-user] IllegalArgumentException: Comparison method violates its general contract! - PROPOSED FIX
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From: Janda M. <ja...@cr...> - 2014-06-30 12:17:37
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Hi,
I isolated the problem with small test case:
The problem is in calling "LineSegment:orientationIndex" from "SubgraphDepthLocater$DepthSegment:compareTo".
Test case:
public class TestBuffer {
public static void main(String[] args) {
LineSegment segment1 = new LineSegment(13.4411564327, 51.8421162769, 13.4428710938, 51.8422851563);
LineSegment segment2 = new LineSegment(13.4428710938, 51.8422851563, 13.4427022144, 51.8439998173);
int index1 = segment1.orientationIndex(segment2);
int index2 = segment2.orientationIndex(segment1);
System.out.printf("Index: %d, %d%n", index1, index2);
}
}
This test prints "Index: 1, 1".
Method "compareTo" requires output "Index: 1, -1". I think that "LineSegment:orientationIndex" works correctly but it is not suitable for "DepthSegment:compareTo"
Proposed solution:
1) Keep "LineSegment:orientationIndex" without change
2) make SubgraphDepthLocater$DepthSegment STATIC class - to reduce allocated memory
3) introduce static method "orientationIndex" to SubgraphDepthLocater$DepthSegment
- this is modified version of "LineSegment:orientationIndex"
private static int orientationIndex(LineSegment s1, LineSegment seg)
{
int orient0 = CGAlgorithms.orientationIndex(s1.p0, s1.p1, seg.p0);
int orient1 = CGAlgorithms.orientationIndex(s1.p0, s1.p1, seg.p1);
if (orient0 == orient1) return orient0;
return 0;
}
4) modify compareTo method in DepthSegment
private int compare(final DepthSegment other) {
/**
* try and compute a determinate orientation for the segments.
* Test returns 1 if other is left of this (i.e. this > other)
*/
int orientIndex = orientationIndex(upwardSeg, other.upwardSeg); // MODIFIED call local method
/**
* If comparison between this and other is indeterminate,
* try the opposite call order.
* orientationIndex value is 1 if this is left of other,
* so have to flip sign to get proper comparison value of
* -1 if this is leftmost
*/
if (orientIndex == 0)
orientIndex = -1 * orientationIndex(other.upwardSeg, upwardSeg); // MODIFIED call local method
// if orientation is determinate, return it
if (orientIndex != 0)
return orientIndex;
// otherwise, segs must be collinear - sort based on minimum X value
return compareX(this.upwardSeg, other.upwardSeg);
}
-----------
I don't know whether this is correct modification without introducing regression. I hope that this help fix this issue.
Thank you
Martin
----- Original Message -----
From: "Janda Martin" <ja...@cr...>
To: jts...@li..., "jts-devel" <jts...@li...>
Sent: Monday, June 30, 2014 12:17:32 PM
Subject: [Jts-topo-suite-user] IllegalArgumentException: Comparison method violates its general contract!
Hi,
I got "IllegalArgumentException: Comparison method violates its general contract!" in BufferOp.
This issue was introduced by changes in Java 7 sorting algorithm.
It was already discussed on this mailing list (2012-11-05 - http://ehc.ac/p/jts-topo-suite/mailman/message/30057535/ ) .
I'm using JTS 1.13. And I don't see fix in trunk (I didn't test trunk version). This is showstopper for me. Will this issue be fixed soon? Or should I try to fix it and send patch to JTS?
Thank you
Martin
Stack trace from older post:
Exception in thread "pool-357-thread-8" java.lang.IllegalArgumentException: Comparison method violates its general contract!
at java.util.ComparableTimSort.mergeLo(ComparableTimSort.java:714)
at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:451)
at java.util.ComparableTimSort.mergeCollapse(ComparableTimSort.java:376)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:182)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
at java.util.Arrays.sort(Arrays.java:472)
at java.util.Collections.sort(Collections.java:155)
at com.vividsolutions.jts.operation.buffer.SubgraphDepthLocater.getDepth(SubgraphDepthLocater.java:66)
at com.vividsolutions.jts.operation.buffer.BufferBuilder.buildSubgraphs(BufferBuilder.java:289)
at com.vividsolutions.jts.operation.buffer.BufferBuilder.buffer(BufferBuilder.java:156)
at com.vividsolutions.jts.operation.buffer.BufferOp.bufferFixedPrecision(BufferOp.java:368)
at com.vividsolutions.jts.operation.buffer.BufferOp.bufferReducedPrecision(BufferOp.java:356)
at com.vividsolutions.jts.operation.buffer.BufferOp.bufferReducedPrecision(BufferOp.java:320)
at com.vividsolutions.jts.operation.buffer.BufferOp.computeGeometry(BufferOp.java:312)
at com.vividsolutions.jts.operation.buffer.BufferOp.getResultGeometry(BufferOp.java:299)
at com.vividsolutions.jts.operation.buffer.BufferOp.bufferOp(BufferOp.java:175)
at com.vividsolutions.jts.geom.Geometry.buffer(Geometry.java:1180)
at ch.valnova.ontracktiler.simplify.TileGeometrySimplifier.simplifyGeometry(TileGeometrySimplifier.java:110)
at ch.valnova.ontracktiler.DatabaseTiler$ProcessingRunnable.doProcessing(DatabaseTiler.java:134)
at ch.valnova.ontracktiler.DatabaseTiler$ProcessingRunnable.run(DatabaseTiler.java:117)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
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