[mongodb, java] Extract ISODate as date string from MongoDb using Java driver 3.8

[Question] 

Below is mongo collection:

{"_id":ObjectId("5a8f997fcdc2960adae4f919"),"COBDate":ISODate("2018-02-15T18:30:00.000Z"),"Version":1}

Code to extract COBDate from mongo

MongoCollection<Document>collection=db.getCollection(collectionName);
String jsonMessage=collection.find().iterator().next().toJson;
JSONObject message=new JSONObject(jsonMessage);
String date=message.get(COBDate).toString();

But it extracted the value of COBDate as {"$date":1518719400000}.

Can someone help me to get it in some date format like "2018-02-15T18:30:00.000Z"?

mongo Driver 3.8 and mongodb 3.2.6 i am getting above issue. mongo driver 3.6 working fine...

Solution:-

          // or use a connection string
          MongoClientURI connectionString = new MongoClientURI("mongodb://localhost:27017");
          MongoClient mongoClient = new MongoClient(connectionString);

          MongoDatabase database = mongoClient.getDatabase("testdb");

          MongoCollection<Document> collection = database.getCollection("user");

          //JsonWriterSettings writerSettings = new JsonWriterSettings(JsonMode.SHELL, true);           
          //System.out.println(doc.toJson(writerSettings));

          Document myDoc = collection.find().first();
          //System.out.println(myDoc.toJson(writerSettings));
          System.out.println("output (JSON) = " + com.mongodb.util.JSON.serialize(myDoc));
          System.out.println("output (JSON) = " + myDoc);

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[Answer]

If you assign the find response to a org.bson.Document (rather than invoking toJson() on it) then you can read any of its attributes in a type specific manner. For a Date attribute this means invoking document.getDate("...").

For example:

MongoCollection<Document> collection = mongoClient.getDatabase("...").getCollection("...");

Document document = collection.find().iterator().next();

// now you have a Date object ...
Date cob = document.getDate("COBDate");

/// ... which you can use _as is_ or format into a String as follows ...
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");

/// this will print: 2018-02-15T18:30:00.000Z
System.out.println(df.format(cob));

[출처] https://stackoverflow.com/questions/51284197/extract-isodate-as-date-string-from-mongodb-using-java-driver-3-8