Determine whether JSON is a JSONObject or JSONArray

I found better way to determine:

String data = "{ ... }";
Object json = new JSONTokener(data).nextValue();
if (json instanceof JSONObject)
  //you have an object
else if (json instanceof JSONArray)
  //you have an array

tokenizer is able to return more types: http://developer.android.com/reference/org/json/JSONTokener.html#nextValue()

There are a couple ways you can do this:

1. You can check the character at the first position of the String (after trimming away whitespace, as it is allowed in valid JSON). If it is a {, you are dealing with a JSONObject, if it is a [, you are dealing with a JSONArray.
2. If you are dealing with JSON (an Object), then you can do an instanceof check. yourObject instanceof JSONObject. This will return true if yourObject is a JSONObject. The same applies to JSONArray.

This is the simple solution I'm using on Android:

JSONObject json = new JSONObject(jsonString);

if (json.has("data")) {

    JSONObject dataObject = json.optJSONObject("data");

    if (dataObject != null) {

        //Do things with object.

    } else {

        JSONArray array = json.optJSONArray("data");

        //Do things with array
    }
} else {
    // Do nothing or throw exception if "data" is a mandatory field
}

Presenting an another way :

if(server_response.trim().charAt(0) == '[') {
    Log.e("Response is : " , "JSONArray");
} else if(server_response.trim().charAt(0) == '{') {
    Log.e("Response is : " , "JSONObject");
}

Here server_response is a response String coming from server