CODEWITHSUNDEEP
javajsongenerics
Nahydrin
Nahydrin

Reputation: 13517

Gson fromJson using generic super class

I'm trying to get a json array to deserliaze when using generics, see my work below:

public class Lookup<T extends Profile> {

    protected final Class<T> getSuperClass() {
        ParameterizedType superClass = (ParameterizedType)this.getClass().getGenericSuperclass();
        return (Class<T>)(superClass.getActualTypeArguments().length == 0 ? BasicProfile.class : superClass.getActualTypeArguments()[0]);
    }

    protected final Class<T[]> getSuperClassArray() {
        ParameterizedType superClass = (ParameterizedType)this.getClass().getGenericSuperclass();
        return (Class<T[]>)(superClass.getActualTypeArguments().length == 0 ? BasicMojangProfile[].class : superClass.getActualTypeArguments());
    }

    public void doWork() { // This Works
        String jsonText = "{id=3, name=Derp}";
        T result = new Gson().fromJson(jsonText, this.getSuperClass());
        // Will be whatever T is (defined elsewhere), unless this class
        // is created without a super class then properly defaults to
        // the BasicProfile
    }

    public void doArrayWork() { // DOES NOT WORK
        String jsonText = "[{id=3, name=Derp}]";
        T[] result = new Gson().fromJson(jsonText, ?);
        // Have tried the following (in place of the ?):
        // new TypeToken<T>(){}.getType()
        // new TypeToken<T[]>(){}.getType()
        // new TypeToken<List<T>>(){}.getType() // with List<T> result
        // this.getSuperClassArray()
    }

}

How can I get doArrayWork to function properly? I do not want to pass whatever T is as a parameter to the method.

Upvotes: 1

Views: 126

Answers (1)

Ferrybig
Ferrybig

Reputation: 18834

You can use Array.newInstance(this.getSuperClass(), 0).getClass().

This creates a array based on the class passed to the method, then it calls getCLass() on that array to get the real class object representing that array.

Upvotes: 2

Related Questions