Initializing a final variable in an abstract class (Java)

Question

So I have this abstract class

 public abstract class A {

   protected final boolean b;

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

}

And this class that extends A

 public class C extends A{

   protected C() {
    super(false);
   }

}

I dont want "b" to be able to change its' value once it's initialized But I dont know how to do it without the compiler going haywire.

Any suggestions are welcome. Thanks in advance.

EDIT1: static removed from b.

EDIT 2: Ok realised the problem and fixed see above. Special thanks to J.Lucky :)

Answer 1

I'd suggest you make use of the final keyword.

Try the following codes:

abstract class A {

    final protected boolean b;

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

    //No setter method
    //public abstract void setB(boolean b);
    public abstract boolean getB();
}

class C extends A {

    C(boolean b) {
        super(b);
    }

    @Override
    public boolean getB() {
        return b;
    }
}

Sample implementation would be:

public static void main(String args[]) {
    C c = new C(true);
    System.out.println(c.getB());
}

Since b now is a final variable, you will be forced to initialize it on your constructor and you will not have any way of changing b anymore. Even if you provide a setter method for b, the compiler will stop you.

EDIT 2:

Say you created another class called 'D' and this time you know you want to set it to false by default. You can have something like:

class D extends A {
    D() {
        super(false);
    }

    //You can also overload it so that you will have a choice
    D(boolean b) {
        super(b);
    }


    @Override
    public boolean getB() {
        return b;
    }

    public static void main(String[] args) {
        D defaultBVal = D();
        D customBVal = D(true);

        System.out.println(defaultBVal.getB()); //false
        System.out.println(customBVal.getB()); //true
    }
}