getting or fetching the Value from an Object Array , from an HashMap

Question

I have got the following Map Structure

{CDetails=[{"collegeName":"Peters Stanford","collegeLoc":"UK"},{}]}

I am trying to get the collegeLoc value from the above mentioned structure

This is what i tried

public static void main(String[] args) {
     Map < String, Object > empMap = new HashMap < > ();

    JSONObject collegeNameJsonObj = new JSONObject();
    collegeNameJsonObj.put("collegeName", "Peters Stanford");

    JSONObject collegeIdJsonObj = new JSONObject();
    collegeNameJsonObj.put("collegeLoc", "UK");

    JSONArray jsonArray = new JSONArray();
    jsonArray.add(collegeNameJsonObj);
    jsonArray.add(collegeIdJsonObj);

    empMap.put("CDetails", jsonArray);


  System.out.println(empMap.entrySet().stream().filter(map->map.getKey().equals("CDetails")).map(map->map.getValue()).collect(Collectors.toList()));

Struck here , unable to loop / parse further .

how to get the collegeLoc value in this case ? any help would be great .

Can you get value from JSONObject by key,like jsonObject.getAsString(key)? — TongChen
– TongChen, Commented May 5, 2020 at 3:04

Karthick Ramachandran · Accepted Answer · 2021-06-16 14:47:39Z

1

Try the following code,

empMap
    .entrySet()
    .stream()
    .filter(map -> map.getKey().equals("CDetails"))
    .forEach(e -> {
            JSONArray jsArray = (JSONArray) e.getValue();
            for (Object jsObject : jsArray) {
                JSONObject obj = (JSONObject) jsObject;
                if (obj.containsKey("collegeLoc")) {
                    System.out.println(obj.getAsString("collegeLoc"));
                }
            }
    });

edited Jun 16, 2021 at 14:47

answered May 5, 2020 at 3:17

Karthick Ramachandran

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Mikhail Kopylov · Accepted Answer · 2020-05-05 03:03:41Z

0

It might be

json.getJSONArray("CDetails").getJSONObject(0).getString("slogan")

Or, which is better, create a Value Object and serialize / deserialize it. It will be much easier to manipulate & navigate with Java class rather than with a pure JSON document.

class ValueObject {
  @JsonProperty("CDetails")
  private List<Detail> details;

  static class Detail {
    private String collegeName;
    private String collegeLoc;
  }
}

answered May 5, 2020 at 3:03

Mikhail Kopylov

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TongChen · Accepted Answer · 2020-05-05 03:06:50Z

0

If use net.minidev.json json lib,try the follow code:

JSONArray array = (JSONArray) empMap.get("CDetails");

array.stream().filter(o -> {
    JSONObject jsonObject = (JSONObject) o;
    return jsonObject.containsKey("collegeLoc");
}).map(o -> {
    JSONObject jsonObject = (JSONObject) o;
    return jsonObject.getAsString("collegeLoc");
}).forEach(System.out::println);

answered May 5, 2020 at 3:06

TongChen

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