java - Jackson - Deserialize Generic class variable

Question

I had posted the question wrongly. I am posting the question correctly here ...

I am getting a json string as a HTTP response. I know the structure of it. It is as follows:

public class Json<T> {
    public Hits<T> hits;
}
public class Hits<T> {
    public int found;
    public int start;
    public ArrayList<Hit<T>> hit;
}
public class Hit<T> {
    public String id;
    public Class<T> data;
}

The "data" field can belong to any class. I will know it at runtime only. I will get it as a parameter. This is how I am deserializing.

public <T> void deSerialize(Class<T> clazz) {
    ObjectMapper mapper = new ObjectMapper();
    mapper.readValue(jsonString,  new TypeReference<Json<T>>() {});
}

But I am getting an error -

cannot access private java.lang.class.Class() from java.lang.class. Failed to set access. Cannot make a java.lang.Class constructor accessible

Answer 1

You will need to build JavaType explicitly, if generic type is only dynamically available:

// do NOT create new ObjectMapper per each request!
final ObjectMapper mapper = new ObjectMapper();

public Json<T> void deSerialize(Class<T> clazz, InputStream json) {
    return mapper.readValue(json,
      mapper.getTypeFactory().constructParametricType(Json.class, clazz));
}