Java Static Variables and inheritance and Memory

Question

I know that if I have multiple instance of the same class all of them are gonna share the same class variables, so the static properties of the class will use a fixed amount of memory no matter how many instance of the class I have.

My question is: If I have a couple subclasses inheriting some static field from their superclass, will they share the class variables or not?

And if not, what is the best practice/pattern to make sure they share the same class variables?

Answer 1

If I have a couple subclasses inheriting some static field from their superclass, will they share the class variables or not?

Yes They will share the same class variables throughout the current running Application in single Classloader.
For example consider the code given below, this will give you fair idea of the sharing of class variable by each of its subclasses..

class Super 
{
    static int i = 90;
    public static void setI(int in)
    {
        i = in;
    }
    public static int getI()
    {
        return i;
    }
}
class Child1 extends Super{}
class Child2 extends Super{}
public class ChildTest
{
    public static void main(String st[])
    {
        System.out.println(Child1.getI());
        System.out.println(Child2.getI());
        Super.setI(189);//value of i is changed in super class
        System.out.println(Child1.getI());//same change is reflected for Child1 i.e 189
        System.out.println(Child2.getI());//same change is reflected for Child2 i.e 189
    }
}