Deep clone by collecting the fields

Question

I have classes which aim to contain many attributes of different types. I would want to automatically deep clone all of them rather than writing an instruction for each of them:

class AttributesContainer implements Cloneable {
    Type1 a1 = new Type1(...), a2 = new Type1(...);
    Type2 b1 = new Type2(...);
    ...

    public AttributesContainer clone() {
        AttributesContainer ac = (AttributesContainer) super.clone();

        // Regroup that like using a loop
        ac.a1 = a1.clone();
        ac.a2 = a2.clone();
        ac.b1 = b1.clone();
        ...

        return ac;
    }
}

I have thought about adding the fields in a table each time but I could not change the reference of the fields:

class ContainerAbstract implements Cloneable {
    public <T> T add(T t) {
        // adds the reference into a list
        return t;
    }

    public ContainerAbstract clone() {
        ContainerAbstract ca = (ContainerAbstract) super.clone();

        // copy the attributes

        return ca;
    }
}

class AttributesContainer extends ContainerAbstract implements Cloneable {
    Type1 a1 = add(new Type1(...)), a2 = add(new Type1(...));
    Type2 b1 = add(new Type2(...));
    ...

    public AttributesContainer clone() {
        AttributesContainer ac = (AttributesContainer) super.clone();
        return ac;
    }
}

I have also thought that I could return a wrapper in the add() method but it would introduce an extra method get() to call each time I want to access an attribute:

AttributesContainer ac = new AttributesContainer();
ac.get()...;

It there a way to change the fields to there source, like we could achieve that in C using a pointer?

NB: I already checked Copy fields between similar classes in java, How do you make a deep copy of an object in Java? and http://www.java2s.com/Tutorial/Java/0125__Reflection/Returnalistofallfieldswhateveraccessstatusandonwhateversuperclasstheyweredefinedthatcanbefoundonthisclass.htm.

EDIT: One of the reasons I don't use the serialization is that in fact, I have a final property for which I just want a fresh new instance.

I thought about making it transient and then giving it a new object but I can't, since it is final:

class A {
    private Double d = new Double(2);
    public final transient B b = new B();

    public A copy() {
        A a = (A) DeepCopy.copy(this);
        a.b = new B(); // Error, b is final
        return a;
    }
}

Answer 1

Always check when articles are written (or questions are asked/answered), otherwise you'll get plenty of misconceptions. The text I quoted in my comment is in the bottom of the page. If you don't see it, use the "Find in page" functionality of your browser.

Serializing and deserializing final fields is not a problem either. You can't write this: a.b = new B(); // Error, b is final, but you don't need to. Serialization is implemented on the JVM level and it can perform plenty of tricks, such as creating objects without calling any constructors.

Answer 2

Finally, the only answer I found without needing to change a final attribute is to change in the class DeepCopy in http://javatechniques.com/blog/faster-deep-copies-of-java-objects/ the ObjectOutputStream method to replace attributes of the class Type with new ones.

ObjectOutputStream out = new ObjectOutputStream(fbos) {
    {
        enableReplaceObject(true);
    }

    @Override
    protected Object replaceObject(Object arg0) throws IOException {
        // TODO Auto-generated method stub
        if(arg0 instanceof Type) {
            for(Constructor<?> constructor : arg0.getClass().getConstructors()) {
                Class<?>[] parameterTypes = constructor.getParameterTypes();
                if(parameterTypes.length == 0 /* Number of arguments in the constructor of new Type(...) */)
                    try {
                        return constructor.newInstance(/* Arguments to the constructor */);
                    } catch (InstantiationException | IllegalAccessException
                            | IllegalArgumentException
                            | InvocationTargetException e) {
                        e.printStackTrace();
                    }
            }

            try {
                throw new Exception("The constructor needed to create a new Type was not found.");
            } catch(Exception e) {
                e.printStackTrace();
            }

            return null;

        } else {
            return super.replaceObject(arg0);
        }
    }
};
out.writeObject(orig);
out.flush();
out.close();