MongoDB find in the database from java - example

//Your need mongoDB driver for this!!!!!!!!!!!

package second;

import com.mongodb.*;

import java.net.UnknownHostException;
import java.util.Random;

public class Query {
    public static void main(String sf[]) throws UnknownHostException {
        //connect to DB on localhost on default port  (27017)
        MongoClient client = new MongoClient();
        //select DB "course"
        DB courseDB = client.getDB("course");
        //use collection "queryTests"
        DBCollection collection = courseDB.getCollection("queryTests");
        //cleaning collection if it is not empty
        collection.drop();

        //populate collection with such kind objects: { "x" : 0 , "y" : 62}
        for (int i = 0; i < 10; i++) {
            collection.insert(new BasicDBObject("x", new Random().nextInt(2)).append("y", new Random().nextInt(100)));
        }

        // for example I want to find all objects that have x=0;  10>=y>=90
        DBObject search = new BasicDBObject("x", 0).append("y", new BasicDBObject("$gte", 10).append("$lte", 90));

        System.out.println("Count from BasicDBObject");
        //just counting such objects
        long k = collection.count(search);
        System.out.println(k);

        System.out.println("Find from BasicDBObject");
        //ask to find all objects that suits "search" BasicDBObject patter, and ak not to retrieve their id's
        DBCursor cursor = collection.find(search, new BasicDBObject("_id", false));
        //print the cursor data
        showDataFromCursor(cursor);

        //the fancy way to do the same is criteria builder, doing absolutely the same (finds all objects that have x=0;  10>=y>=90)
        QueryBuilder queryBuilder = QueryBuilder.start("x").is(0).and("y").greaterThanEquals(10).lessThanEquals(90);

        System.out.println("Count from Criteria");
        long j = collection.count(queryBuilder.get());
        System.out.println(j);

        System.out.println("Find from Criteria");
        DBCursor cursor1 = collection.find(queryBuilder.get(), new BasicDBObject("_id", false));
        showDataFromCursor(cursor1);

    }

    //method that prints out data from cursor
    public static void showDataFromCursor(DBCursor cursor) {

        try {
            while (cursor.hasNext()) {
                DBObject cur = cursor.next();
                System.out.println(cur);
            }
        } finally {
            cursor.close();
        }

    }
}