Question

I have an arraylist is of a class type “checker”, that stores different objects (float, string etc).

ArrayList<checker> VecAtoms;
checker aux=new checker();
aux.atom="C";
aux.x=0f;
aux.y=0f;
aux.z=0f;
VecAtoms.add(aux);

At this point (VecAtoms.add(aux);) Java asks to switch to debug mode, but no erros is shown in the console, nor any detail that could help me figure out what happens. How should I solve that?

Answer 1

ArrayList<checker> VecAtoms; is pointing to null.

VecAtoms.add(aux);

You are operating on null reference which results in NullPointerException.

Have your arraylist instantiated, example:

ArrayList<checker> VecAtoms = new ArrayList<checker>();

as well as make sure aux is not pointing to null.