When does garbage collection happen for a class with static data

Question

I want to make some data easily available throughout my application. I have a few variables in a class with static data, which get written to and read from at several different points.

This worked fine for a while, but now at one point where I expect to be able to retrieve an ArrayList all I get is "null".

I am wondering if the static class has been sent to the "garbage collector". Not sure what's going on, if you can help that would be much appreciated.

Answer 1

you can try to make it final, and recompile the code in order to see if some other class CHANGES the reference to null:

public class Global {

    public final static List<String> data = new ArrayList<String>();

}

this allow to write:

Global.data.add("foo");

but not:

Global.data = null;

Answer 2

I have a few variables in a static class, which get written to... at several different points.

As you are confessing yourself, so a null can be assigned to the variable at one or more of those different points. :)