How to parse multidimensional json array in java

Question

I have a two dimensional JSON array object like below

{"enrollment_response":{"condition":"Good","extra":"Nothig","userid":"526398"}}

I would like to parse the above Json array object to get the condition, extra, userid.So i have used below code

JSONParser parser = new JSONParser();

    try {

        Object obj = parser.parse(new FileReader("D:\\document(2).json"));

        JSONObject jsonObject = (JSONObject) obj;

        String name = (String) jsonObject.get("enrollment_response");
        System.out.println("Condition:" + name);

        String name1 = (String) jsonObject.get("extra");
        System.out.println("extra: " + name1);



    } catch (FileNotFoundException e) { 
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParseException e) {
        e.printStackTrace();
    }

Its throwing an error as

"Exception in thread "main" java.lang.ClassCastException:
org.json.simple.JSONObject cannot be cast to java.lang.String at
com.jsonparser.apps.JsonParsing1.main(JsonParsing1.java:22)"

Please anyone help on this issue.

I think the error message is pretty clear. What result are you hoping to get by casting an object to a string (you do realize that the value of enrollment_response is an object?)? — Felix Kling
– Felix Kling, Commented Feb 18, 2014 at 9:28
What you have here is not an array at all. It is a Json object with another Json object nested in. — Henry
– Henry, Commented Feb 18, 2014 at 9:30
I would like to get the values of condition,extra and userid — Test1234
– Test1234, Commented Feb 18, 2014 at 9:31
FYI org.json.simple is quite possibly the worst JSON parsing library you could possibly choose. Please, please use something else. Jackson, Gson, or even the old json.org libs are far better. — Brian Roach
– Brian Roach, Commented Feb 18, 2014 at 9:54

Brian Roach · Accepted Answer · 2014-02-18 10:11:29Z

3

First of all: Do not use the JSON parsing library you're using. It's horrible. No, really, horrible. It's an old, crufty thing that lightly wraps a Java rawtype Hashmap. It can't even handle a JSON array as the root structure.

Use Jackson, Gson, or even the old json.org library.

That said, to fix your current code:

JSONObject enrollmentResponseObject = 
    (JSONObject) jsonObject.get("enrollment_response");

This gets the inner object. Now you can extract the inner fields:

String condition = (String) enrollmentResponseObject.get("condition");

And so forth. The whole library simply extends a Hashmap (without using generics) and makes you figure out and cast to the appropriate types.

edited Feb 18, 2014 at 10:11

answered Feb 18, 2014 at 10:05

Brian Roach

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Comments

Shashank Kadne · Accepted Answer · 2014-02-18 09:32:07Z

2

Below line,

String name = (String) jsonObject.get("enrollment_response");

should be

String name = jsonObject.getJSONObject("enrollment_response").getString("condition");

Value of enrollment_response is again a Json.

answered Feb 18, 2014 at 9:32

Shashank Kadne

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3 Comments

Test1234 Over a year ago

I get an error message as "The method getJSONObject(String) is undefined for the type JSONObject"

Shashank Kadne Over a year ago

Can you provide the fully qualified class name for JSONObject. I assumed you are using org.json library.

Brian Roach Over a year ago

@ShashankKadne It's org.json.simple and it's awful.

Enrichman · Accepted Answer · 2014-02-18 10:22:58Z

0

This works, but trust me: change library.

JSONObject jsonObject = (JSONObject) obj;

JSONObject name = (JSONObject) jsonObject.get("enrollment_response");
System.out.println("Condition:" + name);

String name1 = (String) name.get("extra");
System.out.println("extra: " + name1);

edited Feb 18, 2014 at 10:22

answered Feb 18, 2014 at 9:40

Enrichman

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5 Comments

Test1234 Over a year ago

Hi enrichman i got an error as "The method getJSONObject(String) is undefined for the type JSONObject"

Enrichman Over a year ago

As the other answerer posted we thought you were using the org.json library. Can you provide the exact library you're using?

Enrichman Over a year ago

@BrianRoach can I suggest you to switch over the standard and more documented org.json or Jackson?

Brian Roach Over a year ago

@Enrichman I'm not the OP; I was pointing out what lib they're using ;) See my answer.

Enrichman Over a year ago

@BrianRoach ahaha, sorry, you're right! Never seen such an awful JSON library btw. I had to download it to understand it.

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