Week1Homework3.java

/*
 * 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;

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);
    }
}