Last night this error happened again at the same spot. The remedy is still the same: Run only one thread or declare the method synchronized. I still think, something is not right there... java.lang.NullPointerException at uk.me.parabola.imgfmt.app.net.RoadDef.compareTo(RoadDef.java:700) at uk.me.parabola.imgfmt.app.net.RoadDef.compareTo(RoadDef.java:56) at java.util.HashMap.compareComparables(Unknown Source) at java.util.HashMap$TreeNode.treeify(Unknown Source) at java.util.HashMap.treeifyBin(Unknown Source) at java.util.HashMap.putVal(Unknown Source) at java.util.HashMap.put(Unknown Source) at uk.me.parabola.imgfmt.app.net.TableA.addArc(TableA.java:86) at uk.me.parabola.imgfmt.app.net.NOD1Part.addNode(NOD1Part.java:229) at uk.me.parabola.imgfmt.app.net.NOD1Part.subdivideHelper(NOD1Part.java: 305) at uk.me.parabola.imgfmt.app.net.NOD1Part.subdivide(NOD1Part.java:266) at uk.me.parabola.imgfmt.app.net.RoadNetwork.splitCenters(RoadNetwork.ja va:249) at uk.me.parabola.imgfmt.app.net.RoadNetwork.getCenters(RoadNetwork.java :256) at uk.me.parabola.mkgmap.build.MapBuilder.makeMap(MapBuilder.java:231) at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:120) at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:82) at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:253) at uk.me.parabola.mkgmap.main.Main$1.call(Main.java:249) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) -- View this message in context: http://gis.19327.n5.nabble.com/NPE-with-mkgmap-3320-tp5813472p5823284.html Sent from the Mkgmap Development mailing list archive at Nabble.com.