Do final (constant) instance (non-static) variables act like class (static) variables?

Question

In the following example, the variable b is declared final, but not static. That means it's a constant instance variable. However, because it's constant, none of the Passenger objects can change its value. So isn't it better to declare it static and make it a class variable, so that there is only one copy to be used by all instantiated objects?

class Passenger {
    int a;
    final int b = 0;

    void drive() {
        System.out.println("I'm driving!");
    }
}

Answer 1

The purpose of final but non-static variables is to have an object-wide constant. It should be initialized in the constructor:

class Passenger {
    final int b;

    Passenger(int b) {
        this.b = b;
    }
}

If you are always assigning a constant literal value (0) to the final variable, it doesn't make much sense. Using static is preferred so that you are only having a single copy of b:

static final int b = 0;

BTW I don't think having default access modifier was your intention.

Answer 2

It depends on the purpose of b. Usually constants are there for a specific purpose. If you make it static you could accidentally change it in some instance of that class and that will affect all the others.