Mongodb update using Java

You can't really create DBObjects with that dot notation. You have to nest new BasicDBObjects for each level in the document tree.

DBObject toFind = new BasicDBObject("Functions", 
    new BasicDBObject("show-app", 
        new BasicDBObject("calculatedConfigValues", 
            new BasicDBObject("floor", 0))));

Same for the update object

DBObject update = new BasicDBObject("$set",
    new BasicDBObject("Functions", 
        new BasicDBObject("show-app", 
            new BasicDBObject("calculatedConfigValues",
                new BasicDBObject("ceiling", 100)))))

Alternatively, you can use this Helper class for translating json strings into DBObject structures like this.

DBObject toFind = (DBObject) JSON.parse(
    "{'Functions.show-app.calculatedConfigValues.floor':0}"
);

But be aware of that using the JSON class may cause performance problems. It's simply faster to build DBObjects manually.

Not sure if this will solve your problem, but don't you want to update a specific document within a collection within the DB? So something along these lines:

MongoClient mongo = new MongoClient();
DB db = mongo.getDB(DB_NAME);
db.getCollection(COLLECTION_NAME).update(find, set);

I would also define find in this way, because you want the specific object from that collection.

BasicDBObject obj = new BasicDBObject();
obj.put(..., 0);
DBObject find = db.getCollection(COLLECTION_NAME).findOne(obj);

Let me know if this works.