Java Why isn't it allowed to set a protected final field from a subclass constructor?

Question

Why isn't it allowed to set a protected final field from a subclass constructor?

Example:

class A {
    protected final boolean b;

    protected A() {
        b = false;
    }
}

class B extends A {
    public B() {
        super();
        b = true;
    }
}

I think it would make sense in some cases, wouldn't it?

Answer 1

It's because you can't change value of final fields.

But if you really want to se it to different value, you could do:

class A {
    protected final boolean b;

    protected A() {
    this(false);
    }
    protected A(boolean b) {
       this. b = b;
    }
}

class B extends A {
    public B() {
        super(true);
    }
}