Nested list objects with AutoValue/Gson fails with NoSuchMethodError

Question

I'm trying to use a JSON object to convert to a Java object (build with AutoValue) using Gson. The JSON object looks like:

{
    "id": 1,
    "name": "Nutella Pie",
    "ingredients": [
        {
            "quantity": 2,
            "measure": "CUP",
            "ingredient": "Graham Cracker crumbs"
        },
        ...
    ],
    "steps": [
        {
            "id": 5,
            "shortDescription": "Finish filling prep"
        },
        ...
    ]
}

So the Java class (built with AutoValue) looks like:

@AutoValue
public abstract class Recipe {
    @SerializedName("id")
    abstract int id();
    @SerializedName("name")
    abstract String name();
    @SerializedName("ingredients")
    abstract List<Ingredient> ingredients();
    @SerializedName("steps")
    abstract List<Step> steps();

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

The create method in the TypeAdapterFactory is:

public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
    Class<? super T> rawType = type.getRawType();

    if (rawType.equals(Ingredient.class)) {
        return (TypeAdapter<T>) Ingredient.typeAdapter(gson);
    }
    if (rawType.equals(Recipe.class)) {
        return (TypeAdapter<T>) Recipe.typeAdapter(gson);
    }
    if (rawType.equals(Step.class)) {
        return (TypeAdapter<T>) Step.typeAdapter(gson);
    }

    return null;
}

However, I'm having the error:

NoSuchMethodError: No static method getParameterized

This getParameterized is a GsonTypeAdapter method, and apparently is not implemented.

If I change the JSON and the Java classes to a nested object instead of a nested object list, it works fine.

I don't know what is going on. Any ideas?

EDIT: I made some progress. Acording to the AutoValue GSON Extension docs:

To have support for fields with generic parameters (eg. List) you need to upgrade your Gson dependency to at least 2.8.0, which introduces the helper TypeToken.getParameterized() see Gson Changelog.

This way, my code to generate the Type adapter is:

public static <Ingredient,Step> TypeAdapter<Recipe<Ingredient,Step>> typeAdapter(Gson gson,
                  TypeToken<? extends Recipe<Ingredient,Step>> typeToken) {
    return new AutoValue_Recipe.GsonTypeAdapter(gson,typeToken);
}

However, Im having a problem using that on the TypeAdapterFactory, since it has to return a TypeAdapter<T>, not a TypeAdapter<Recipe<Ingredient,Step>>. Tried casting, but no success.

What do I do? Add a new TypeAdapterFactory?

Answer 1

NoSuchMethodError: No static method getParameterized

I'm assuming you're using com.ryanharter.auto.value:auto-value-gson:0.4.6, but you have an older Gson version prior to 2.8.0. You're getting the exception because the AutoValue generator uses Gson 2.8.0 under the hood, and Gson 2.8.0 introduced TypeToken.getParameterized (see commit 9414b9b3b61d59474a274aab21193391e5b97e52). And at the runtime JVM expects your Gson to provide the TypeToken.getParameterized method. Since you seem to have an older Gson version, it throws the error.

There's also a note on Gson 2.8.0 in the auto-value-gson documentation:

You will also need a normal runtime dependency for gson itself.

compile 'com.google.code.gson:gson:2.8.0'

If you're using Apache Maven, just make sure that you have the latest Gson:

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.0</version>
</dependency>

This should work. If you cannot upgrade Gson for whatever reason, try to downgrade the AutoValue Gson generator.