GSON: Expected a string but was BEGIN_OBJECT?

Question

I\'m trying to use GSON to parse some very simple JSON. Here\'s my code:

    Gson gson = new Gson();

    InputStreamReader reader = new InputStreamReader(ge         


        

Answer 1

The JSON structure is an object with one element named "access_token" -- it's not just a simple string. It could be deserialized to a matching Java data structure, such as a Map, as follows.

import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class GsonFoo
{
  public static void main(String[] args)
  {
    String jsonInput = "{\"access_token\": \"abcdefgh\"}";

    Map map = new Gson().fromJson(jsonInput, new TypeToken>() {}.getType());
    String key = map.get("access_token");
    System.out.println(key);
  }
}

Another common approach is to use a more specific Java data structure that matches the JSON. For example:

import com.google.gson.Gson;
import com.google.gson.annotations.SerializedName;

public class GsonFoo
{
  public static void main(String[] args)
  {
    String jsonInput = "{\"access_token\": \"abcdefgh\"}";

    Response response = new Gson().fromJson(jsonInput, Response.class);
    System.out.println(response.key);
  }
}

class Response
{
  @SerializedName("access_token")
  String key;
}