ArrayList of items implementing Parcelable being treated as Serializable and causing error

[percula]

I am getting this error:

java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = java.util.ArrayList)

Looking at the PaperParcel created classes, it appears my ArrayList<object that implements parcelable> is being treated as a serializable, instead of a TypedList. I created an alternative class that doesn't use PaperParcel and it works just fine. Either I'm missing something or this is a bug in PaperParcel. Either way, thanks for the great library!

Please see a sample I created on GitHub.

[grandstaish]

Hmm, this one is tricky because you're using ArrayList which implements Serializable except that it technically isn't because the items contained inside of it don't also implement Serializable 😕

If AObjectPaperParcel used List instead of ArrayList, then it'd work.

Alternatively you could add the following custom TypeAdapter which would handle any ArrayList of Parcelables:

public class ArrayListOfParcelablesTypeAdapter<T extends Parcelable> implements TypeAdapter<ArrayList<T>> {
  @Override public ArrayList<T> readFromParcel(@NonNull Parcel source) {
    ArrayList<T> outList = new ArrayList<>();
    source.readList(outList, ArrayListOfParcelablesTypeAdapter.class.getClassLoader());
    return outList;
  }

  @Override public void writeToParcel(ArrayList<T> value, @NonNull Parcel dest, int flags) {
    dest.writeList(value);
  }
}

Then add it like so:

@ProcessorConfig(adapters = {
    @Adapter(value = ArrayListOfParcelablesTypeAdapter.class, nullSafe = true)
})
public interface PaperParcelConfig {
}

I'm going to add a fix to PaperParcel to ensure that this sort of thing won't compile in the future.

[grandstaish]

Never mind, unfortunately this can't be fixed because there's no way to tell from the type system that this is not Serializable at runtime 😢

The options for fixing are mentioned in the comment above.

To prevent compilation from working you can also disable support for Serializable like so:

@ProcessorConfig(options = @PaperParcel.Options(allowSerializable = false))
public interface PaperParcelConfig {
}

Sorry about that!

[percula]

Thanks @grandstaish for the help! I tried both methods and ended up going with changing them to List (actually I'm using Kotlin so MutableList). Now they're treated as parcelables :-).