Get data from nested JSON Object in Java Android

Question

How I can get the "fields" objects 0,1,2,3,4 & only the "name" object string of every object using JSONOBJECT

 [
    {
        "name": "Bank1",
        "fields": {
            "0": {
                "name": "Email",
                "slug": "email",
                "type": "input"
            },
            "1": {
                "name": "City",
                "slug": "city",
                "type": "input"
            },
            "2": {
                "name": "Screenshot",
                "slug": "screenshot",
                "type": "file"
            },
            "3": {
                "name": "Full Name",
                "slug": "full-name",
                "type": "input"
            }
        },
        "status": "Active"
    },
    {
        "name": "Bank2",
        "fields": {
            "0": {
                "name": "Email",
                "slug": "email",
                "type": "input"
            },
            "1": {
                "name": "City",
                "slug": "city",
                "type": "input"
            },
            "2": {
                "name": "Screenshot",
                "slug": "screenshot",
                "type": "file"
            },
            "4": {
                "name": "Submitted Date",
                "slug": "submitted-date",
                "type": "calendar"
            }
        },
        "status": "Active"
    }
]

& this is what I try to done

public void onResponse(String response) {
                        try {
                            JSONArray jsonArray = new JSONArray(response);
                         
                            for (int i = 0; i < jsonArray.length(); i++) {
                                JSONObject jsonObject = jsonArray.getJSONObject(i);

                               
                                String p_name = jsonObject.getString("name");
                                JSONObject jo = jsonObject.getJSONObject("fields");

                                String j1 = jo.getString("0");
                                if (!j1.isEmpty()){
                                    JSONObject jo1 = jo.getJSONObject("0");
                                    String f_name1 = jo1.getString("name");
                                    Log.d("Field1.", f_name1);
                                }
}}catch block...

but the problem is, it gives me value of the object null like [value 4 is null] cuz there is no object for 4 in the first object of fields. please help me solve this prob, appreciate your answers thankyou :)

Use JSONObject.keys to iterate properties

Selvin
– Selvin

2021-08-24 15:08:32 +00:00
Commented Aug 24, 2021 at 15:08 — Selvin
– Selvin, Commented Aug 24, 2021 at 15:08

Mayur Gajra · Accepted Answer · 2021-08-24 15:12:29Z

4

You can use keys() iterator of json object & loop on it using while (keys.hasNext())

For your example, it would look something like this:

private void parseJson(String response) {
        try {
            JSONArray jsonArray = new JSONArray(response);

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);

                JSONObject jo = jsonObject.getJSONObject("fields");

                Iterator<String> keys = jo.keys();
                while (keys.hasNext()) {
                    String key = keys.next();
                    JSONObject jo1 = jo.getJSONObject(key);
                    String f_name1 = jo1.getString("name");
                    Log.d("Field1.", f_name1);
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

answered Aug 24, 2021 at 15:12

Mayur Gajra

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1 Comment

AndroWaqar Over a year ago

Thanks for the answer but is there a way to add this in arraylist one by one only of the first fields object and then the next one @Mayur Gajra

Andrzej Więcławski · Accepted Answer · 2021-08-24 21:09:40Z

0

There are some problems with get all keys properly in my IDE/JDK11, so I decided to loop over an ArrayList, basing on @MayurGajra solution, ex:

private static List<List<String>> parseJson(String response) throws JSONException {
    JSONArray jsonArray = new JSONArray(response);
    List<List<String>> result = new ArrayList<>();

    for (int i = 0; i < jsonArray.length(); i++) {
        JSONObject jsonObject = jsonArray.getJSONObject(i);
        JSONObject jo = jsonObject.getJSONObject("fields");

        List<Object> list = new ArrayList<>();
        jo.keys().forEachRemaining(list::add);
        List<String> subList = new ArrayList<>();

        for (Object o : list) {
            String key;
            if (isString(o))
                key = (String) o;
            else
                continue;
            JSONObject jo1 = jo.getJSONObject(key);
            String f_name1 = jo1.getString("name");
            subList.add(f_name1);
        }
        result.add(subList);
    }
    return result;
}

private static boolean isString(Object o) {
    try {
        String result = (String) o;
    } catch (ClassCastException e) {
        return false;
    }
    return true;
}

The result obtained after processing the above json is as follows:

[[Email, City, Screenshot, Full Name], [Email, City, Screenshot, Submitted Date]]

but it have not to be a List of Lists ;)

-- edit --

To get only first list of elements labeled "name":

    try {
        System.out.println(parseJson(yourJsonAsString).get(0).toString());
    } catch (JSONException e) {
        System.out.println("JSONException:" + e.getMessage());
    }

The result of above is:

[Email, City, Screenshot, Full Name]

edited Aug 24, 2021 at 21:09

answered Aug 24, 2021 at 21:03

Andrzej Więcławski

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7 Comments

AndroWaqar Over a year ago

according to your answer means it gives me only specific index value or every fields object

Andrzej Więcławski Over a year ago

Well, but you wrote above that you are looking for a way to "add this in arraylist one by one only of the first fields object and then the next one". Have I misunderstood you?

AndroWaqar Over a year ago

I have updated my question @Andrzej Więcławski

Andrzej Więcławski Over a year ago

And you got fourth element from each object, no matter what the key has. The algorithm does not pay attention to whether the numerical order of the keys is maintained. It could be 0,1,2,4 or 0,1,2,4. Do you expect the both results for 0,1,2,3,4 keys?

AndroWaqar Over a year ago

no there might be 0123 or may be 012 or all five 01234

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