Update Json value in json Array in Java

{
  "page": {
    "size": 2,
    "number": 2
  },
  "places": [
    {
      "eventName": "XYZ",
      "createdByUser": "xyz@xyz.com",
      "modifiedDateTime": "2021-03-31T09:59:48.616Z",
      "modifiedByUser": "xyz@xyz.com"
    }   
   ]}

I am trying to update the "eventName" field with new String. I tried with the following code, It updates the field but returns only four fields in the json array.

    public String modifyJson() throws Exception{
    String jsonString =  PiplineJson.payload(PiplineJson.filePath());
    System.out.println(jsonString);
    JSONObject jobject = new JSONObject(jsonString);
    String uu = jobject.getJSONArray("places")
                       .getJSONObject(0)
                       .put("eventName", randomString())
                       .toString();
    System.out.println(uu);
    return uu; 
}

This is what the above code does.

{
  "eventName": "ABCD",
  "createdByUser": "xyz@xyz.com",
  "modifiedDateTime": "2021-03-31T09:59:48.616Z",
  "modifiedByUser": "xyz@xyz.com"
}

I am trying to get the complete json once it updates the eventName filed.

{
  "page": {
    "size": 2,
    "number": 2
  },
  "places": [
    {
      "eventName": "ABCD",
      "createdByUser": "xyz@xyz.com",
      "modifiedDateTime": "2021-03-31T09:59:48.616Z",
      "modifiedByUser": "xyz@xyz.com"
    }   
   ]}

>Solution :

The problem is the way that you are chaining the operations together. The problem is that you are calling toString() on the result of the put call. The put calls returns the inner JSONObject that it was called on. So you end up serializing the wrong object.

Changing this:

String uu = jobject.getJSONArray("places")
                   .getJSONObject(0)
                   .put("eventName", randomString())
                   .toString();

to

jobject.getJSONArray("places")
       .getJSONObject(0)
       .put("eventName", randomString());
String uu = jobject.toString();

should work.