Question

I have an odd situation where i want to be able to be able to persist a variable in memory.. like a global variable I can pin in the JVM.

Is this possible? I remember doing something similar in college, but can’t find it by googling. I have a logic problem that has some artificial constraints that make this the best possible solution.

EDIT 1:

I will need to update the value of the variable.

EDIT 2 :

I appreciate the responses guys. I’m a .net programmer and hadn’t used java since college. Thanks again.

Answer 1

Yes, using a static field:

public class GlobalVariableHolder {
    public static int globalVariable;
}

Note, however, that this is considered a bad practice and can lead to unexpected results that are hard to debug. The way to not use a global variable is to pass it around as an argument or methods where you need it.

If you are still sure you need this, in order to guard yourself as much as possible, use synchronization. Even better, if the variable is going to be primitive (int, long, etc), you can use AtomicInteger‘s getAndAdd() or addAndGet() method.