need GSON to return a Java JSONArray

Question

I'm not able to return a JSONArray, instead my object appears to be a String. the value of myArray is the same value as jsonString. The object is a String object and not a JSONArray. and both jsonString and myArray prnt:

[{"id":"100002930603211",
  "name":"Aardvark Jingleheimer",
  "picture":"shortenedExample.jpg" },
 {"id":"537815695",
   "name":"Aarn Mc",
   "picture":"shortendExample.jpg" },
 {"id":"658471072",
   "name":"Adrna opescu",
   "picture":"shortenedExample.jpg"
}]

How can I convert this to an actual Java JSONArray? thanks!

           //arrPersons is an ArrayList

        Gson gson = new Gson();
        String jsonString = gson.toJson(arrPersons);

        JsonParser parser = new JsonParser();
        JsonElement myElement = parser.parse(jsonString);
        JsonArray myArray = myElement.getAsJsonArray();

This can't be right. getAsJsonArray() returns a JSONArray. Java is statically typed, what you wrote above would not compile if myArray wasn't really a JsonArray. — Max
– Max, Commented Apr 4, 2012 at 23:39
that's part of my question. the Gson JsonArray object is different than Java JSONArray object. I would like to create a JSONArray. — Tom
– Tom, Commented Apr 5, 2012 at 0:28
? There is no the Java JSONArray object. Do you mean JSONArray from json.org? — Max
– Max, Commented Apr 5, 2012 at 1:19
Hi Max, this is my first Java project so please forgive my ignorance on missing that JSONArray was not a Java Object. I did figure out how to accomplish my task of taking a JSONArray and alphabetizing by "name" element. I posted the code below. The path was JSONArray -- ArrayList--sort list--back to JSONArray through GSON. Would love to hear of a better way though. thanks! — Tom
– Tom, Commented Apr 5, 2012 at 17:57

Parker · Accepted Answer · 2012-08-02 14:52:55Z

1

I think you can do what you want without writing out a json string and then re-reading it:

List<Person> arrPersons = new ArrayList<Person>();

// populate your list

Gson gson = new Gson();
JsonElement element = gson.toJsonTree(arrPersons, new TypeToken<List<Person>>() {}.getType());

if (! element.isJsonArray()) {
// fail appropriately
    throw new SomeException();
}

JsonArray jsonArray = element.getAsJsonArray();

answered Aug 2, 2012 at 14:52

Parker

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Tom · Accepted Answer · 2012-04-05 17:53:03Z

    public JSONArray getMessage(String response){

    ArrayList<Person> arrPersons = new ArrayList<Person>();
    try {
        // obtain the response
        JSONObject jsonResponse = new JSONObject(response);
        // get the array
        JSONArray persons=jsonResponse.optJSONArray("data");


        // iterate over the array and retrieve single person instances
        for(int i=0;i<persons.length();i++){
            // get person object
            JSONObject person=persons.getJSONObject(i);
            // get picture url
            String picture=person.optString("picture");
            // get id
            String id=person.optString("id");
            // get name
            String name=person.optString("name");

            // construct the object and add it to the arraylist
            Person p=new Person();
            p.picture=picture;
            p.id=id;
            p.name=name;
            arrPersons.add(p);
        }
        //sort Arraylist
        Collections.sort(arrPersons, new PersonSortByName());


    Gson gson = new Gson();
    //gson.toJson(arrPersons);

    String jsonString = gson.toJson(arrPersons);

    sortedjsonArray = new JSONArray(jsonString);



    } catch (JSONException e) {

        e.printStackTrace();
    }

    return sortedjsonArray;

}



public class PersonSortByName implements Comparator<Person>{

    public int compare(Person o1, Person o2) {
    return o1.name.compareTo(o2.name);
    }
    }

  public class Person{
       public String picture;
       public String id;
       public String name;
  }

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