Android Parcelable和通过引用传递的对象

Question

I have numerous objects, some of which would have different ArrayList properties (of custom objects). The same object could occurr in any of the above ArrrayList.

I would like to have those objects being passed by reference so that when I edit one of them, the changes are reflected across all ArrayLists/objects.

I need to pass those objects or ArrayLists as Parcelable across different Activities. I think Parcelable interface is causing passing by reference not working (which kind of makes sense considering you need to implement new constructor, so supposedly the new object is created/cloned every time Parcel is being created and passed?).

I was wondering what would be the best approach to handle this situation, ie. how can I achieve or simulate the behaviour of the objects being passed by reference. I dont really want to use any of the persistent storage tehniques if it can be avoided.

Answer 1

I know this is an old question, but since I'me here :)

Anyway what I do is pass the id of the item I want and then use Application to hold my data.

For example let's say I have a class named Order, each order has many Line(s) something like this

class Order {
    UUID _id;
    List<Line> _lines = new ArrayList<>();
}

class Line {
    UUID _id;
    Product _product ;
    BigDecimal _price;
    int _quantity;
}

etc.

So I have an implementation of Application where I store all my (in memory) orders like this:

public class App extends Application {
    public static final List<Order> Orders = new Order();

    public static final Order GetOrder(UUID id) {
        for (Order o : Orders) {
            If(o.get_id().Equals(id))
            return o;
        }
        return null;
    }
}

Then if I wish to pass a specific order I do something like this:

Intent i = new Intent(this, OrderEdit.class);
i.putExtra(OrderEdit.ID, my_order.get_id().ToString());
startActivity(i);

and on the other side :

UUID id = UUID.fromString(getArguments().getExtra(ID));
App.GetOrder(id); 

that way you always have a reference passed.