MongoDB 2.4 - Java (update, remove)

import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.List;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
import com.mongodb.ServerAddress;

public class MongoDB {

private static MongoClient client;
private static DBCollection collection;

private static void createCollection() throws UnknownHostException {
MongoDB.client = new MongoClient(new ServerAddress("localhost", 27017));

DB database = client.getDB("databaseName");

MongoDB.collection = database.getCollection("collectionName");

collection.drop();
}

public static void main(String[] args) throws UnknownHostException {
createCollection();

List<String> names = Arrays.asList("alice", "bobby", "cathy", "david",
"ethan");

for (String name : names) {
collection.insert(new BasicDBObject("_id", name));
}

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "alice"), new BasicDBObject(
"age", 24));

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "alice"), new BasicDBObject(
"gender", "F"));

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "bobby"), new BasicDBObject(
"$set", new BasicDBObject("age", "26")));

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "bobby"), new BasicDBObject(
"$set", new BasicDBObject("gender", "F")));

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "frank"), new BasicDBObject(
"$set", new BasicDBObject("gender", "F")), true, false);

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject("_id", "frank"), new BasicDBObject(
"$set", new BasicDBObject("gender", "M")), true, false);

printCollection();
System.out.println("==========");

collection.update(new BasicDBObject(), new BasicDBObject("$set",
new BasicDBObject("title", "Dr.")), false, true);

printCollection();
System.out.println("==========");

collection.remove(new BasicDBObject("_id", "alice"));

printCollection();
System.out.println("==========");

collection.remove(new BasicDBObject());

printCollection();
System.out.println("==========");

client.close();
}

private static void printCollection() {
DBCursor result = null;

try {
result = collection.find();

while (result.hasNext()) {
DBObject document = result.next();

System.out.println(document);
}
} finally {
result.close();
}
}
}