Parsing JSON Array within JSON Object

Question

I have some JSON with the following structure:

{"source":[ {"name":"john","age":20}, {"name":"michael","age":25}, {"name":"sara", "age":23} ] }

I have named this JSON string as mainJSON. I'm trying to access the elements "name" and "age" with the following Java code:

JSONArray jsonMainArr = new JSONArray(mainJSON.getJSONArray("source")); for (int i = 0; i < jsonMainArr.length(); i++) { // **line 2** JSONObject childJSONObject = jsonMainArr.getJSONObject(i); String name = childJSONObject.getString("name"); int age = childJSONObject.getInt("age"); }

I'm being shown the following exception for line number 2:

org.json.JSONException: JSONArray initial value should be a string or collection or array.

Please guide me as to where I'm making the mistake and how to rectify this.

There is no issue on your source code, I tried it already.

Weidian Huang
– Weidian Huang

2016-12-25 12:50:09 +00:00
Commented Dec 25, 2016 at 12:50 — Weidian Huang
– Weidian Huang, Commented Dec 25, 2016 at 12:50

Chandu · Accepted Answer · 2012-08-16 12:08:42Z

52

mainJSON.getJSONArray("source") returns a JSONArray, hence you can remove the new JSONArray.

The JSONArray contructor with an object parameter expects it to be a Collection or Array (not JSONArray)

Try this:

JSONArray jsonMainArr = mainJSON.getJSONArray("source");

edited Aug 16, 2012 at 12:08

answered Apr 13, 2011 at 13:42

Chandu

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2 Comments

Thompson Over a year ago

How can we parse JSON like this? [{"id":"1","name":"ABC"},{"id":"2","name":"XYZ"}]

Anuj Jindal Over a year ago

This may Help json = "{\"m\"="+json+"}"; and now parse by name 'm'.

Darwind · Accepted Answer · 2013-06-29 17:45:22Z

10

Your code is fine, just replace the following line:

JSONArray jsonMainArr = new JSONArray(mainJSON.getJSONArray("source"));

with this line:

JSONArray jsonMainArr = mainJSON.getJSONArray("source");

edited Jun 29, 2013 at 17:45

Darwind

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answered Jun 29, 2013 at 17:21

Imran Muhammad

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2 Comments

marciokoko Over a year ago

What if the data format received is [{dict1},{dict2},{dict3}]?

Jackie Over a year ago

JSONArray list = new JSONArray(jsonString);

Vinay Vemula · Accepted Answer · 2015-12-22 18:29:23Z

line 2 should be

for (int i = 0; i < jsonMainArr.size(); i++) { // **line 2**

For line 3, I'm having to do

 JSONObject childJSONObject = (JSONObject) new JSONParser().parse(jsonMainArr.get(i).toString());

Kun · Accepted Answer · 2016-04-06 20:47:11Z

private static String readAll(Reader rd) throws IOException { StringBuilder sb = new StringBuilder(); int cp; while ((cp = rd.read()) != -1) { sb.append((char) cp); } return sb.toString(); } String jsonText = readAll(inputofyourjsonstream); JSONObject json = new JSONObject(jsonText); JSONArray arr = json.getJSONArray("sources");

Your arr would looks like: [ { "id":1001, "name":"jhon" }, { "id":1002, "name":"jhon" } ] You can use:

arr.getJSONObject(index)

to get the objects inside of the array.

B. Kemmer · Accepted Answer · 2015-06-15 07:12:37Z

-3

This could be an answer to your question:

JSONArray msg1 = (JSONArray) json.get("source"); for(int i = 0; i < msg1.length(); i++){ String name = msg1.getString("name"); int age = msg1.getInt("age"); }

edited Jun 15, 2015 at 7:12

B. Kemmer

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answered Jun 15, 2015 at 6:47

Rahul

1

3 Comments

abarisone Over a year ago

Could you please elaborate more your answer adding a little more description about the solution you provide?

Hortitude Over a year ago

doesn't work - no reference back to "i" when iterating

Weidian Huang Over a year ago

Cannot cast the string to JSONArray, this doesn't work

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