Make ArrayList<?> containing different objects parcelable

Question

I have two kinds of custom objects Movie and DetailedMovie which are stored into an ArrayList<Object>. After doing a network operation my ArrayList is populated exclusively with either objects of type Movie or of type DetailedMovie. I am using a list of type object because they are linked to an adapter and the adapter then sorts out the views depending on what type of object is in the list.

So, the problem is that I want to store the contents of the ArrayList into a Bundle in onSaveInstanceState. Both my Movie and DetailedMovie objects implement Parcelable, but when I try

List<Object> mObjectMovieList = new ArrayList<>();

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putParcelableArrayList(MOVIE_LIST_KEY, mObjectMovieList);
}

I am told

Wrong 2nd argument type. Found: 'java.util.List<java.lang.Object>', required: 'java.util.ArrayList<? extends android.os.Parcelable>'

How can I get around this?

Answer 1

The reason being for this is that Object class do not extend Parcelable.

1st Option

One of the solution that I can suggest here is to make a parent class that extends Parcelable and then both Movie and DetailedMovie extend that class.

So, it would look like:

List<MovieWrapper> mObjectMovieList = new ArrayList<>();

where MovieWrapper is parent of Movie and DetailedMovie

class Movie extends MovieWrapper 

class DetailedMovie extends MovieWrapper

2nd Option

The other option is to filter the array into specific type and then call putParcelableArrayList

ArrayList<Movie> movieList = mObjectMovieList.stream().filter(p->p instanceOf Movie).collect(Collectors.toCollection(ArrayList::new));
ArrayList<DetailedMovieList> detailedMovieList = mObjectMovieList.stream().filter(p->p instanceOf DetailedMovieList).collect(Collectors.toCollection(ArrayList::new));

outState.putParcelableArrayList(MOVIE_LIST_KEY, movieList);
outState.putParcelableArrayList(DETAILED_MOVIE_LIST_KEY, detailedMovieList);

You may need to amend the above code as it is just a suggestion and can be changed as required.