Parsing Json to List of Items with generic field with Gson

Question

public class OwnCollection{
    private int size;
    private List> data;
}

public class ResponseItem{
    private Str         


        

Answer 1

It doesn't work this way, because the following code

OwnCollection<Game> gc = new Query().<Game>getParsedCollection( ... );

actually doesn't pass Game inside getParsedCollection(). <Game> here only tells the compiler that getParsedCollection() is supposed to return OwnCollection<Game>, but T inside getParsedCollection() (and parseToGenericCollection()) remains erased, therefore TypeToken cannot help you to capture its value.

You need to pass Game.class as a parameter instead

public <T> OwnCollection<T> getParsedCollection(Class<T> elementType) { ... }
...
OwnCollection<Game> gc = new Query().getParsedCollection(Game.class);

and then use TypeToken to link OwnCollection's T with elementType as follows:

Type type = new TypeToken<OwnCollection<T>>() {}
    .where(new TypeParameter<T>() {}, elementType)
    .getType();

Note that this code uses TypeToken from Guava, because TypeToken from Gson doesn't support this functionality.