GSON Android, well, I don't understand it at all

Hello. There are already 3,000,000,000 such questions. But I do not understand at all how to take and learn how to serialize / deserialize Json, using GSON.

There is a response from the server of the form:

    `{"p_result":"ok"}`

This is a Json object, not an array, not anything else.

I need to get this very "ok".

I also have an example of working code for getting values from an array:

    User.java

public class User {
private String p_id;
private String p_name;
private String p_last_name;

public String getId() {
    return p_id;
}

public void setId(String id) {
    this.p_id = id;
}

public String getName() {
    return p_name;
}

public void setName(String name) {
    this.p_name = name;
}

public String getLastName() {
    return p_last_name;
}

public void setLastName(String lastName) {
    this.p_last_name = lastName;
}
}

To it:

public class JsonWorker {

public static List<User> jsonToUserList(String json)
{
    Gson gson = new Gson();
    Type listType = new TypeToken<List<User>>() {}.getType();
    return gson.fromJson(json,listType);
}

}

And the method:

public static List<User> getUserFromServer() throws IOException, JSONException {

    final List<NameValuePair> nameValuePairList = new ArrayList<NameValuePair>();
    nameValuePairList.add(new BasicNameValuePair("query", "spr_employee_get"));
    nameValuePairList.add(new BasicNameValuePair("p_guid", user_guid));
    final String resp = execHttpGet(url, nameValuePairList);
    JSONObject jsonObject = new JSONObject(resp);
    if (jsonObject.has("p_result")) {
        if (jsonObject.getString("p_result").equalsIgnoreCase("ok"))
            return JsonWorker.jsonToUserList(jsonObject.getJSONArray("p_item").toString());

    }
    return new ArrayList<User>();
}

And I can't even do it by analogy...