I'm a new user of the program. I have done a simulation of the solar system in 3 dimensions and sometimes when I rotate the view I get this error (copied from console):
Exception in thread "Thread-2" java.lang.NullPointerException at org.opensourcephysics.drawing3d.simple3d.SimpleElementTrail.computePositions(Unknown Source) at org.opensourcephysics.drawing3d.simple3d.SimpleElementTrail.processChanges(Unknown Source) at org.opensourcephysics.drawing3d.Element.processChanges(Unknown Source) at org.opensourcephysics.drawing3d.ElementTrail.processChanges(Unknown Source) at org.opensourcephysics.drawing3d.Group.processChanges(Unknown Source) at org.opensourcephysics.drawing3d.Group.processChanges(Unknown Source) at org.opensourcephysics.drawing3d.simple3d.SimpleDrawingPanel3D.paintDrawableList(Unknown Source) at org.opensourcephysics.drawing3d.simple3d.SimpleDrawingPanel3D.paintEverything(Unknown Source) at org.opensourcephysics.drawing3d.simple3d.SimpleDrawingPanel3D.render(Unknown Source) at org.opensourcephysics.drawing3d.simple3d.SimpleDrawingPanel3D.render(Unknown Source) at org.opensourcephysics.drawing3d.DrawingPanel3D.render(Unknown Source) at org.colos.ejs.library.control.drawing3d.ControlDrawingPanel3D.finalUpdate(Unknown Source) at org.colos.ejs.library.control.EjsControl.finalUpdate(Unknown Source) at org.colos.ejs.library.Animation.update(Unknown Source) at org.colos.ejs.library.Animation.step(Unknown Source) at org.colos.ejs.library.Animation.run(Unknown Source) at java.lang.Thread.run(Unknown Source)
It doesn't happen always in the same evolution step, sometimes it happens sooner and other times it takes more time to happen.
I don't know how to fix it so I would appreciate some help.
Good morning I also present a similar problem, I'm doing a simulation in which the user selects that activity wants to do. So it is necessary to restart variables, hide some windows and make visible other. The error that occurs is as follows, Exception in thread "Thread-8" java.lang.NullPointerException at java.text.DecimalFormat.checkAndSetFastPathStatus(Unknown Source) at java.text.DecimalFormat.fastFormat(Unknown Source) at java.text.NumberFormat.format(Unknown Source) at org.opensourcephysics.display.axes.CartesianType1.formatNum(Unknown Source) at org.opensourcephysics.display.axes.CartesianType1.getLeftGutter(Unknown Source) at org.opensourcephysics.display.axes.CartesianType1.draw(Unknown Source) at org.opensourcephysics.display.axes.CartesianInteractive.draw(Unknown Source) at org.opensourcephysics.display.PlottingPanel.paintFirst(Unknown Source) at org.opensourcephysics.display.DrawingPanel.paintEverything(Unknown Source) at org.opensourcephysics.display.DrawingPanel.render(Unknown Source) at org.opensourcephysics.display.DrawingPanel.render(Unknown Source) at org.colos.ejs.library.control.swing.ControlDrawablesParent.finalUpdate(Unknown Source) at org.colos.ejs.library.control.EjsControl.finalUpdate(Unknown Source) at org.colos.ejs.library.Animation.update(Unknown Source) at org.colos.ejs.library.Animation.step(Unknown Source) at org.colos.ejs.library.Animation.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Thank you Best regard
Both problems are completely different. The one with the 3D trail may be caused by a synchronization issue. I run your example (a nice one, by the way!) and could not reproduce it. The synchronisation of the Java VM in MacOSX can be better than in Windows...
The other problem is probably due to a bad choice of the min an max of X or Y in the plotting panel.
