Query in Java as in Mongo shell 【Jongo】

what ？

how ？

DB db = new MongoClient().getDB("dbname");

Jongo jongo = new Jongo(db);
MongoCollection friends = jongo.getCollection("friends");

MongoCursor<Friend> all = friends.find("{name: 'Joe'}").as(Friend.class);
Friend one = friends.findOne("{name: 'Joe'}").as(Friend.class);

why ?

other