How to parse through json files with nested records from java application?

Question

I have a json file with such data:

"records": {
            "abc@zabili.com": {
                "user_id": 523,
                "user_name": "abc",
                "user_email": "abc",
                "time": 10747.5
            },
            "amn@zabili.com": {
                "user_id": 699,
                "user_name": "Amn",
                "user_email": "amn",
                "time": 4439
            },
            "bco@zabili.com": {
                "user_id": 320,
                "user_name": "Bco",
                "user_email": "bco",
                "time": 1927.85
            },
            "bcag@zabili.com": {
                "user_id": 425,
                "user_name": "Bcag",
                "user_email": "bcag",
                "time": 572.8
            },
            "chan@zabili.com": {
                "user_id": 376,
                "user_name": "Chan",
                "user_email": "chan",
                "time": 9769.69
            }
        }

I want to print the user_name and time for each user. How do i do that?

Use [jackson](https://github.com/FasterXML/jackson-databind/) jar to parse json. — Kaustubh Khare, Jul 19 '18 at 10:06
Possible duplicate of [How to parse JSON in Java](https://stackoverflow.com/questions/2591098/how-to-parse-json-in-java) — CodeMatrix, Jul 19 '18 at 10:08

score 1 · Answer 1 · edited Jul 19 '18 at 10:38

Try this:

String jsonData = "Your JSON data here";
JSONArray jsonArray = new JSONArray(jsonData);
for(int i = 0; i < jsonArray.length(); i++) {
    JSONObject jsonObject = jsonArray.getJSONObject(i);

    // get user_id
    String str_user_id = jsonObject.getString("user_id");

    // get user_name
    String str_user_name = jsonObject.getString("user_name");
     //... for other elements
}

score 0 · Answer 2 · answered Jul 19 '18 at 10:40

String toBeParsed = "String Json";

JSONObject jsonObject = new JSONObject(toBeParsed);

String userObject = jsonObject.optString("records");

JSONArray userDetailsArray = new JSONArray(userObject).length()

for(int i = 0 ; i< userDetailsArray; i++)
{
    JSONObject singleUserObject = userDetailsArray.getJSONObject(i);
    String userName = singleUserObject.getString("user_id");
    String userTime = singleUserObject.getString("user_name");
    // try printing the name & time here
}

score 0 · Answer 3 · answered Jul 19 '18 at 11:33

Use gson to parse string to HashMap, like this:

Gson gson = new Gson();
HashMap map = gson.fromJson("your-json-str", HashMap.class);
Collection c = map.values();
for(Object o: c){
    map ret = (Map)o;
    String user_id = o.get("user_id");
    ....
}

score 0 · Answer 4 · answered Jul 19 '18 at 11:52

As @Kaustubh Khare say, use jackson

ObjectMapper objectMapper = new ObjectMapper();
JsonNode jsonNode = objectMapper.readTree(jsonStr);//jsonStr is your json str
JsonNode records = jsonNode.get("records");
Iterator<JsonNode> elements = records.elements();
while (elements.hasNext()) {
    JsonNode next = elements.next();
    System.out.println(next.get("user_name"));
    System.out.println(next.get("time"));
}

How to parse through json files with nested records from java application?

4 Answers4