[java] Why do I get this Java console error message...

somewhere you''re using a NULL pointer.. debug it and catch the exception

Start by looking in your CityBoy.update method. That''s where the NullPointer exception is coming from.

-Byron

Thanks for your replies. What exactly is a NullPointer exception
and what needs to be done to it?

It will emerge when using a pointer to null, duhh
something like this:

Weapon ref = new Weapon(); Weapon ref2 = ref; yadda,yadda... ref = null; ref2.use(); // EXCEPTION!! ref2 points at null/nothing

It doesn't mean that it HAVE to like that, it's one possible error.
Anyway, the thing is that you are using a ptr that you thought pointed to an object, but somehow the object doesn't exist, it has been discarded.

PS. why is it called pointer!?? shouldn't it be called NullReferenceException? Hmmm, don't know.

regards

/Mankind gave birth to God.

Edited by - silvren on October 9, 2001 5:13:55 AM

the error message points to this line specifically:

cjv.draw(offGrfx);

but doesn''t seem to affect the running of the applet.

maybe

cjv
or
offGrfx
is a NULL-pointer

I would bet that rapso is right.


/Mankind gave birth to God.

NullPointer exception means that your "reference" is pointing to absolutely nothing. You might not have initialized the reference. For Example:
//a valid reference that will throw a NullPointerException:
Object myRef;
myRef.toString();//this line will throw a NullPointerException

//a valid reference that will not throw a NullPointerException:
Object myRef;
myRef = new Object();//it is now pointing to an object in memory
myRef.toString();//this line will NOT throw a NullPointerException