Java tutorial
/* * Copyright (c) 2008 - 2013 10gen, Inc. <http://10gen.com> * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ package com.tengen.home; import com.mongodb.AggregationOutput; import com.mongodb.BasicDBObject; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBObject; import com.mongodb.MongoClient; import java.net.UnknownHostException; public class Week1Homework3 { public static void main(String[] args) throws UnknownHostException { MongoClient client = new MongoClient(); DB database = client.getDB("m101"); DBCollection collection = database.getCollection("funnynumbers"); // Not necessary yet to understand this. It's just to prove that you // are able to run a command on a mongod server AggregationOutput output = collection.aggregate( new BasicDBObject("$group", new BasicDBObject("_id", "$value").append("count", new BasicDBObject("$sum", 1))), new BasicDBObject("$match", new BasicDBObject("count", new BasicDBObject("$gt", 2))), new BasicDBObject("$sort", new BasicDBObject("_id", 1))); int answer = 0; for (DBObject doc : output.results()) { answer += (Double) doc.get("_id"); } System.out.println("THE ANSWER IS: " + answer); } }