How to convert a Android SqlBrite model class to implement Parcelable

Question

I am building an app where I am using SQLBrite sql wrapper for all my database operations. Also, I am using Auto Value to handle all my getters and setters automatically using Google AutoValue library.

Now, my issue is to handle the device rotation and to handle that my putParcelable() method expects two parameters where the first is the KEY and the second is the value of Parcelable type. As I said earlier my Recipe class (code below) is a SQLBrite implemented class and doesn't implement Parcelable. I would like some help to convert this to implement the Parcelable interface.

@AutoValue
public abstract class Recipe {
    public abstract int id();
    public abstract String name();
    public abstract List<Ingredients> ingredients();
    public abstract List<Step> steps();
    public abstract int servings();
    public abstract String image();

    public static Builder builder() {
        return new AutoValue_Recipe.Builder();
    }

    public static TypeAdapter<Recipe> typeAdapter(Gson gson) {
        return new AutoValue_Recipe.GsonTypeAdapter(gson);
    }

    @AutoValue.Builder
    public abstract static class Builder {
        public abstract Builder id(int id);
        public abstract Builder name(String name);
        public abstract Builder ingredients(List<Ingredients> ingredients);
        public abstract Builder steps(List<Step> steps);
        public abstract Builder servings(int servings);
        public abstract Builder image(String image);

        public abstract Recipe build();
    }
}

Now, I tried converting the above code to implement the Parcelable interface, however, now my code is not working. Please help me convert this class to implement Parcelable interface.

@AutoValue
public abstract class Recipe implements Parcelable {
    public static final String ID = "id";
    public static final String NAME = "name";
    public static final String INGREDIENTS = "ingredients";
    public static final String STEPS = "steps";
    public static final String SERVINGS = "servings";
    public static final String IMAGE = "image";

    private int id;
    private String name;
    private List<Ingredients> ingredients;
    private List<Step> steps;
    private int servings;
    private String image;

    public abstract int id();
    public abstract String name();
    public abstract List<Ingredients> ingredients();
    public abstract List<Step> steps();
    public abstract int servings();
    public abstract String image();

    public static Recipe.Builder builder() {
        return new AutoValue_Recipe.Builder();
    }

    public static TypeAdapter<Recipe> typeAdapter(Gson gson) {
        return new AutoValue_Recipe.GsonTypeAdapter(gson);
    }

    public static final class Builder {
        private final ContentValues values = new ContentValues();
        List<Ingredients> ingredient;
        List<Step> step;

        public Recipe.Builder id(int id) {
            values.put(ID, id);
            return this;
        }

        public Builder name(String name) {
            values.put(NAME, name);
            return this;
        }

        public Builder ingredients(List<Ingredients> ingredients) {
        *//*for(int i=0; i<ingredients.size(); i++) {
            values.put(INGREDIENTS, ingredients.get(i).ingredient());
        }*//*
            this.ingredient = ingredients;
            return this;
        }

        public Builder steps(List<Step> steps) {
            *//*for(int i=0; i<steps.size(); i++) {
                values.put(STEPS, steps.get(i));
            }*//*
            this.step = steps;
            return this;
        }

        public Builder servings(int servings) {
            values.put(SERVINGS, servings);
            return this;
        } 

        public Builder image(String image) {
            values.put(IMAGE, image);
            return this;
        }

        public Recipe build() {
            Recipe recipe = null;
            recipe.id = (int) values.get(ID);
            recipe.name = (String) values.get(NAME);
            recipe.ingredients = ingredient;
            recipe.steps = step;
            recipe.servings = (int) values.get(SERVINGS);
            recipe.image = (String) values.get(IMAGE);

            return recipe;
        }
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeInt(id);
        dest.writeString(name);
        dest.writeList(ingredients);
        dest.writeList(steps);
        dest.writeInt(servings);
        dest.writeString(image);
    }
}

Edit: I will using the modified class to handle my device rotation to save scroll state of my recycler view inside a fragment. My onSaveInstanceState() method looks something like this,

private static final String BUNDLE_RECYCLER_LAYOUT = "BUNDLE_RECYCLER_LAYOUT";
ArrayList<Recipe> mRecipeList = new ArrayList<>(0);

@Override
public void onSaveInstanceState(Bundle bundle) {
    super.onSaveInstanceState(bundle);
   bundle.putParcelable(BUNDLE_RECYCLER_LAYOUT,
   mRecipeListRecyclerView.getLayoutManager().onSaveInstanceState());

   bundle.putParcelableArrayList(BUNDLE_RECYCLER_RECIPE_DATA, mRecipeList);
}

The second parameter inside the putParcelable is of Parcelable type.

My onCreateView() method is as shown:

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup 
container, @Nullable Bundle savedInstanceState) {

     View view = inflater.inflate(R.layout.fragment_recipe_list, container, false);
    unbinder = ButterKnife.bind(this, view);

    if(savedInstanceState != null) {
        Parcelable savedRecyclerViewState = savedInstanceState.getParcelable(BUNDLE_RECYCLER_LAYOUT);
        mRecipeListRecyclerView.getLayoutManager().onRestoreInstanceState(savedRecyclerViewState);
        mRecipeList = savedInstanceState.getParcelableArrayList(BUNDLE_RECYCLER_RECIPE_DATA);
        mRecipeListAdapter.refreshRecipes(mRecipeList);
    } else {
        mRecipeList = getArguments().getParcelableArrayList(BUNDLE_RECYCLER_RECIPE_DATA);
    }

    mRecipeListAdapter = new RecipeListAdapter(getContext(), mRecipeList, recipeId
            -> mRecipeListPresenter.loadRecipeDetails(recipeId));
    mRecipeListAdapter.setHasStableIds(true);

    gridLayoutManager = new GridLayoutManager(getContext(), mGridColumnCount);
    mRecipeListRecyclerView.setLayoutManager(gridLayoutManager);
    mRecipeListRecyclerView.setHasFixedSize(true);
    mRecipeListRecyclerView.setAdapter(mRecipeListAdapter);

    return view;
}

Any help would be great as I am stuck while converting the class to implement the Parcelable interface.

Answer 1

        mRecipeListRecyclerView.getLayoutManager().onRestoreInstanceState(savedRecyclerViewState);

You do not need to call onRestoreInstanceState(). This is already called automatically by the Android system. Additionally, you do not need to save and restore the ArrayList yourself. RecyclerView already takes care of these details for you.

As for saving the scroll position, you should do a little more research. For example, I found ListView jumps to the top on screen orientation change with a quick search. This link has a clear example of how to do what you want.

This answer is about ScrollView but the example code is very similar to what you need.