Compare list of JSONArray in ArrayList

Question

I have an ArrayList containing a list of JSONArrays

staffArray = new ArrayList<JSONArray>();

the JSONArray is in a form of this:

[
    {
      "id": "k40dn-dff02-mm1",
      "name": "staff1",
      "tel": "0123456789",
    },
    {
      "id": "ch2mq-pmw01-ps6",
      "name": "staff2",
      "tel": "9876543210",
    }
    ...
]

And the ArrayList will be containing different sizes of JSONArray. Now I want to check in the ArrayList for each JSONArray, if they contain the same value for "id". So say that if the ArrayList has three different sizes of JSONArray, how can I tell the they each contain a JSONObject with the same value for "id" in it.

So far I have tried this to extract the string:

for(int i = 0; i < staffArray.size(); i++){
    JSONArray jsonArray = new JSONArray();
    jsonArray = staffArray.get(i);
    for(int j = 0; j < jsonArray.length(); j ++){
        JSONObject json = null;
        try {
            json = jsonArray.getJSONObject(j);
            String id = json.getString("id");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

earthw0rmjim · Accepted Answer · 2017-06-08 08:38:48Z

1

If you would like to check for duplicate IDs in your ArrayList, you could do something like this:

ArrayList<JSONArray> staffArray = new ArrayList<>();

Set<String> ids = new HashSet<>();
for (JSONArray array : staffArray) {
    for (int i = 0; i < array.length(); i++) {
        JSONObject obj = array.getJSONObject(i);
        if (!ids.add(obj.getString("id"))) {
            // duplicate IDs found, do something
        }
    }
}

edited Jun 8, 2017 at 8:38

answered Jun 8, 2017 at 7:02

earthw0rmjim

19.5k9 gold badges54 silver badges65 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

JerryKo Over a year ago

Thanks for your reply, what I want is to find duplicate in different JSONArrays, say that ArrayList contains three JSONArrays and check if each JSONArray has a key "id" with the same value

earthw0rmjim Over a year ago

@JerryKo I see. You just have to move the Set of IDs outside the outer loop then. See my edited answer.

urag · Accepted Answer · 2017-06-08 07:06:05Z

How about using group by to group the json arrays with same id something like this

public static void groupById(List<JSONArray> staffArray) {
    Map<String, List<JSONArray>> jsonArraysById = staffArray.stream().collect(Collectors.groupingBy(jsonArray -> getIdFromJsonArray(jsonArray)));
    jsonArraysById.forEach((id, arrays) -> {
        System.out.println("Arrays with id " + id + " are " + arrays);
    });
}

public static String getIdFromJsonArray(JSONArray jsonArray) {
    String result = null;
    for (int j = 0; j < jsonArray.length(); j++) {
        JSONObject json = null;
        try {
            json = jsonArray.getJSONObject(j);
            result = json.getString("id");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    return result;
}

Collectives™ on Stack Overflow

Compare list of JSONArray in ArrayList

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related