How to retrieve only one column from collection in mongodb using java?

Question

I want to retrieve only ID column with value less than 4,

MongoDatabase database = client.getDatabase("d");

     MongoCollection<org.bson.Document> contCol = database.getCollection("test");
     BasicDBObject query = new BasicDBObject();
     query.put("ID",1);

 FindIterable<org.bson.Document> it = contCol.find().projection(excludeId());

Doesn't give me the required output. The collection test has two columns, namely ID and name ; the query is returning both the columns, I want to get only the ID column.

Answer 1

To specify which columns you want included, you need to specify that in your projection; for example using the include() method .