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Index › Programming Questions & Help › Syntax Questions › NullPointerException with physics library -
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NullPointerException with physics library - ? (Read 833 times)
softhook
NullPointerException with physics library - ?
Dec 8th, 2006, 3:49pm  
Hi there I am building a complicated application with the traer.physics library. Can anybody help me track down the error/build an exception check? Where should the exception check go?


java.lang.NullPointerException

at traer.physics.ParticleSystem.applyForces(ParticleSystem.java:123)

at traer.physics.RungeKuttaIntegrator.step(RungeKuttaIntegrator.java:193)

at traer.physics.ParticleSystem.tick(ParticleSystem.java:48)

at Temporary_3929_814.normal(Temporary_3929_814.java:122)

at Temporary_3929_814.draw(Temporary_3929_814.java:111)

at processing.core.PApplet.handleDisplay(PApplet.java:1318)

at processing.core.PGraphics.requestDisplay(PGraphics.java:564)

at processing.core.PApplet.run(PApplet.java:1413)

at java.lang.Thread.run(Thread.java:613)

java.lang.NullPointerException

at traer.physics.ParticleSystem.applyForces(ParticleSystem.java:123)

at traer.physics.RungeKuttaIntegrator.step(RungeKuttaIntegrator.java:193)

at traer.physics.ParticleSystem.tick(ParticleSystem.java:48)

at Temporary_3929_814.normal(Temporary_3929_814.java:122)

at Temporary_3929_814.draw(Temporary_3929_814.java:111)

at processing.core.PApplet.handleDisplay(PApplet.java:1318)

at processing.core.PGraphics.requestDisplay(PGraphics.java:564)

at processing.core.PApplet.run(PApplet.java:1413)

at java.lang.Thread.run(Thread.java:613)
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softhook
Re: NullPointerException with physics library - ?
Reply #1 - Dec 8th, 2006, 5:16pm  
Ok I figured out that it is the

physics.tick( 1.0 );

that is throwing the exception. Is that a bad thing if i catch it and carry on? How can I avoid it?
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JohnG
Re: NullPointerException with physics library - ?
Reply #2 - Dec 8th, 2006, 5:30pm  
I think it means there's a problem with your physics setup (null force, divide by zero etc) and just ignoring the error will mean you may only get some forces applied to some particles and the whole system may well be unreliable and inconsistent.
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traer
Re: NullPointerException with physics library - ?
Reply #3 - Dec 16th, 2006, 10:03pm  
Sounds like you made a force with a particle that was null...
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