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

0

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());

answered Dec 22, 2015 at 18:29

Vinay Vemula

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Comments

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

0

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.

edited Apr 6, 2016 at 20:47

answered Apr 6, 2016 at 19:43

Kun

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Comments

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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