Java + MongoDB hello world example

Java mongodb hello world

A simple Java + MongoDB hello world example – how to connect, create database, collection and document, save, update, remove, get and display document (data).

Tools and technologies used :

  1. MongoDB 2.2.3
  2. MongoDB-Java-Driver 2.10.1
  3. JDK 1.6
  4. Maven 3.0.3
  5. Eclipse 4.2

P.S Maven and Eclipse are both optional, just my personal favorite development tool.

1. Create a Java Project

Create a simple Java project with Maven.


mvn archetype:generate -DgroupId=com.mkyong.core -DartifactId=mongodb 
  -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

2. Get Mongo Java Driver

Download mongo-java driver from github. For Maven users, declares mongo-java driver in pom.xml.

pom.xml

<project ...>
  <dependencies>

	<dependency>
		<groupId>org.mongodb</groupId>
		<artifactId>mongo-java-driver</artifactId>
		<version>2.10.1</version>
	</dependency>

  </dependencies>

  <build>
	<plugins>
		<plugin>
			<groupId>org.apache.maven.plugins</groupId>
			<artifactId>maven-compiler-plugin</artifactId>
			<version>2.3.1</version>
			<configuration>
				<source>1.6</source>
				<target>1.6</target>
			</configuration>
		</plugin>
	        <plugin>
			<groupId>org.apache.maven.plugins</groupId>
			<artifactId>maven-eclipse-plugin</artifactId>
			<configuration>
				<downloadSources>true</downloadSources>
				<downloadJavadocs>true</downloadJavadocs>
			</configuration>
		</plugin>

	</plugins>
  </build>

</project>

3. Mongo Connection

Connect to MongoDB server. For MongoDB version >= 2.10.0, uses MongoClient.


	// Old version, uses Mongo
	Mongo mongo = new Mongo("localhost", 27017);

	// Since 2.10.0, uses MongoClient
	MongoClient mongo = new MongoClient( "localhost" , 27017 );

If MongoDB in secure mode, authentication is required.


	MongoClient mongoClient = new MongoClient();
	DB db = mongoClient.getDB("database name");
	boolean auth = db.authenticate("username", "password".toCharArray());

4. Mongo Database

Get database. If the database doesn’t exist, MongoDB will create it for you.


	DB db = mongo.getDB("database name");

Display all databases.


	List<String> dbs = mongo.getDatabaseNames();
	for(String db : dbs){
		System.out.println(db);
	}

5. Mongo Collection

Get collection / table.


	DB db = mongo.getDB("testdb");
	DBCollection table = db.getCollection("user");

Display all collections from selected database.


	DB db = mongo.getDB("testdb");
	Set<String> tables = db.getCollectionNames();
			
	for(String coll : tables){
		System.out.println(coll);
	}
Note
In RDBMS, collection is equal to table.

6. Save example

Save a document (data) into a collection (table) named “user”.


	DBCollection table = db.getCollection("user");
	BasicDBObject document = new BasicDBObject();
	document.put("name", "mkyong");
	document.put("age", 30);
	document.put("createdDate", new Date());
	table.insert(document);

Refer to this Java MongoDB insert example.

7. Update example

Update a document where “name=mkyong”.


	DBCollection table = db.getCollection("user");
	
	BasicDBObject query = new BasicDBObject();
	query.put("name", "mkyong");

	BasicDBObject newDocument = new BasicDBObject();
	newDocument.put("name", "mkyong-updated");
				
	BasicDBObject updateObj = new BasicDBObject();
	updateObj.put("$set", newDocument);

	table.update(query, updateObj);

Refer to this Java MongoDB update example.

8. Find example

Find document where “name=mkyong”, and display it with DBCursor


	DBCollection table = db.getCollection("user");

	BasicDBObject searchQuery = new BasicDBObject();
	searchQuery.put("name", "mkyong");

	DBCursor cursor = table.find(searchQuery);

	while (cursor.hasNext()) {
		System.out.println(cursor.next());
	}

Refer to this Java MongoDB search query example.

9. Delete example

Find document where “name=mkyong”, and delete it.


	DBCollection table = db.getCollection("user");

	BasicDBObject searchQuery = new BasicDBObject();
	searchQuery.put("name", "mkyong");

	table.remove(searchQuery);

Refer to this Java MongoDB delete example.

10. Hello World

Let review a complete Java + MongoDB example, see comments for self-explanatory.

App.java

package com.mkyong.core;

import java.net.UnknownHostException;
import java.util.Date;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.MongoClient;
import com.mongodb.MongoException;

/**
 * Java + MongoDB Hello world Example
 * 
 */
public class App {
  public static void main(String[] args) {

    try {

	/**** Connect to MongoDB ****/
	// Since 2.10.0, uses MongoClient
	MongoClient mongo = new MongoClient("localhost", 27017);

	/**** Get database ****/
	// if database doesn't exists, MongoDB will create it for you
	DB db = mongo.getDB("testdb");

	/**** Get collection / table from 'testdb' ****/
	// if collection doesn't exists, MongoDB will create it for you
	DBCollection table = db.getCollection("user");

	/**** Insert ****/
	// create a document to store key and value
	BasicDBObject document = new BasicDBObject();
	document.put("name", "mkyong");
	document.put("age", 30);
	document.put("createdDate", new Date());
	table.insert(document);

	/**** Find and display ****/
	BasicDBObject searchQuery = new BasicDBObject();
	searchQuery.put("name", "mkyong");

	DBCursor cursor = table.find(searchQuery);

	while (cursor.hasNext()) {
		System.out.println(cursor.next());
	}

	/**** Update ****/
	// search document where name="mkyong" and update it with new values
	BasicDBObject query = new BasicDBObject();
	query.put("name", "mkyong");

	BasicDBObject newDocument = new BasicDBObject();
	newDocument.put("name", "mkyong-updated");

	BasicDBObject updateObj = new BasicDBObject();
	updateObj.put("$set", newDocument);

	table.update(query, updateObj);

	/**** Find and display ****/
	BasicDBObject searchQuery2 
	    = new BasicDBObject().append("name", "mkyong-updated");

	DBCursor cursor2 = table.find(searchQuery2);

	while (cursor2.hasNext()) {
		System.out.println(cursor2.next());
	}

	/**** Done ****/
	System.out.println("Done");

    } catch (UnknownHostException e) {
	e.printStackTrace();
    } catch (MongoException e) {
	e.printStackTrace();
    }

  }
}

Output…


{ "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "name" : "mkyong" , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"}}
{ "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"} , "name" : "mkyong-updated"}
Done

Let use mongo console to check the created database “testdb”, collection “user”, and document.


$ mongo
MongoDB shell version: 2.2.3
connecting to: test

> show dbs
testdb	0.203125GB

> use testdb
switched to db testdb

> show collections
system.indexes
user
> db.user.find()
{ "_id" : ObjectId("51398e6e30044a944cc23e2e"), "age" : 30, "createdDate" : ISODate("2013-03-08T07:08:30.168Z"), "name" : "mkyong-updated" }

Download Source Code

Download it – Java-mongodb-hello-world-example.zip (13KB)

References

  1. Getting started with Java driver
  2. Java-MongoDB driver
author image

mkyong

Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities. Read all published posts by

Comments

avatar
newest oldest most voted
Shubham Aggarwal
Guest
Shubham Aggarwal

“com.mongodb.DB” is now deprecated.

We can use “MongoDatabase database = mongoClient.getDatabase(“myMongoDb”);“ to obtain the database now but with that, many other methods will change, like to get a collection etc.

Carol
Guest
Carol

Thanks, good article.

Macluq
Guest
Macluq

It fails:

03-May-2011 11:32:58 com.mongodb.DBTCPConnector fetchMaxBsonObjectSize
WARNING: null
java.io.IOException: couldn’t connect to [HOSTNAME/HOSTIP:27017] bc:java.net.ConnectException: Connection refused: connect
at com.mongodb.DBPort._open(DBPort.java:205)
(…)

netaji
Guest
netaji

Excellent and very useful for beginers.

Neethu
Guest
Neethu

I have worked on Spring data integration with mango db in java application, can this be done in struts application aslo, I tried to find some examples online but could not find any.

Ramath
Guest
Ramath

Nice one . Good as a starter ! . Appreciate your effort .

dreamshutter
Guest
dreamshutter

Do not need mongoClient.close() in example source?
use only upper code then mongo has too many client connection
then it works slower

ajit
Guest
ajit

For a beginner like me , your tutorials are too good. I appreciate the work that you do to make people understand all the concepts.
Thanks a lot.

nirmal
Guest
nirmal
Mediha
Guest
Mediha

Instead of creating a maven project are there any jars that we can import and then import them?

Mediha
Guest
Mediha

Instead of creating a maven project are there any jars that we can import and then use those instead of pom.xml dependencies?

a
Guest
a

Why would you ever want to do that? Maven has made everything so easy.

Mateen
Guest
Mateen

i just did tried that there are 3 jars listed below that i used, and copied the above sample program it worked just fine

1. mongo-2.10.1.jar
2. mongoconnector.jar
3. mongo-java-driver-2.10.1-javadoc.jar

and you will be good to go

kranthi
Guest
kranthi

Hi mkyong,

Thanks for your sharing your knowledge with us.They are really helpful for us

paul
Guest
paul

dont you want to close the connections?

Kundan Dere
Guest
Kundan Dere

When we run example code . After successful execution of code … whey the java code is not terminating ?
how should i set timeout for same example ?

saurav jain
Guest
saurav jain

Also found more elaboration on how to create collections more explicitly i.e capped collections.
http://lotusmediacentre.com/mongodb-java-hello-world-example/

Umesh
Guest
Umesh

I am fresher in development .
Really this is nice project/example to beginner..
Thank you very much……

Niharika Saxena
Guest
Niharika Saxena

if table has duplicate clolum value after extecuting below script twice.

db.users.insert({username:”niharika”,password:”123456″})
db.users.insert({username:”niharika”,password:”123456″})

db.users.update({username:”niharika”},{$set:{username:”mkyoung”}})

When we try to updtae the cloumn name it updtae only 1 row. ideally it should update all the rows any suggesstion?

{ “_id” : { “$oid” : “53b2f692d28717367aa9ce28”} , “username” : “niharika” , “password” : “123456”}
{ “_id” : { “$oid” : “53b2fd6ed28717367aa9ce29”} , “username” : “mkyoung” , “password” : “123456”}

tan
Guest
tan

public WriteResult update( DBObject q , DBObject o , boolean upsert , boolean multi );

Wojciech Bogucki
Guest
Wojciech Bogucki

How do you convert the result to String, can you use toString() method?

Shahul
Guest
Shahul

Even after adding the org.mongodb dependency, I am not seeing the mongodb java drivers under the external libraries. Please help

idir
Guest
idir

thanks for your job

Nerdcoresteve
Guest
Nerdcoresteve

No matter what I do, I keep getting package com.mongodb does not exist

Nerdcoresteve
Guest
Nerdcoresteve

Ah, never mind. I was putting the dependency in the wrong place. Not too familiar with maven. Thanks for this tutorial. I use your tutorials all the time. 🙂

Tom.TH Lin
Guest
Tom.TH Lin

Thanks for the convenient example, it works perfect!!

Scott
Guest
Scott

When I try to run I am getting:
“Exception in thread “main” java.lang.NoClassDefFoundError: com/mongodb/MongoException”
I simplified the code way down and am still getting it, also ran the original code (attached archive) and got the same thing.

Is this an issue with how I’m linking mongo to the project or something else?

michael
Guest
michael

getDB(String) is deprecated. Use getDatabase(String);

Rashmi Venkatesh
Guest
Rashmi Venkatesh

Hello, I am getting this error when trying to connect to mongodb server through Java code. I am able to connect and run commands in mongo shell. Please help INFO: Exception in monitor thread while connecting to server xxxxxxx:cccc com.mongodb.MongoSocketReadException: Exception receiving message at com.mongodb.connection.InternalStreamConnection.translateReadException(InternalStreamConnection.java:480) at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:225) at com.mongodb.connection.CommandHelper.receiveReply(CommandHelper.java:134) at com.mongodb.connection.CommandHelper.receiveCommandResult(CommandHelper.java:121) at com.mongodb.connection.CommandHelper.executeCommand(CommandHelper.java:32) at com.mongodb.connection.InternalStreamConnectionInitializer.initializeConnectionDescription(InternalStreamConnectionInitializer.java:83) at com.mongodb.connection.InternalStreamConnectionInitializer.initialize(InternalStreamConnectionInitializer.java:43) at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:115) at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:127) at java.lang.Thread.run(Thread.java:662) Caused by: java.net.SocketException: Connection reset at java.net.SocketInputStream.read(SocketInputStream.java:168) at com.mongodb.connection.SocketStream.read(SocketStream.java:85) at com.mongodb.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:491) at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:221) … 8 more com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting for a server that matches ReadPreferenceServerSelector{readPreference=primary}. Client view of cluster state is {type=UNKNOWN,… Read more »

Dennis Wanjama
Guest
Dennis Wanjama

hi i was following your tutorial http://www.mkyong.com/mongodb/java-mongodb-hello-world-example/
this is my error: the method put(String, Object) in the type BasicBSONObject is not applicable for the arguments (String, int)
mycode:
BasicDBObject doc = new BasicDBObject();
doc.put(“age”, 20);

Dennis Wanjama
Guest
Dennis Wanjama

I was following this tutorial
this is my error: the method put(String, Object) in the type BasicBSONObject is not applicable for the arguments (String, int)
mycode:
BasicDBObject doc = new BasicDBObject();
doc.put(“age”, 20);

Amol Jore
Guest
Amol Jore

Thanks Mkyong.. helped me a lot.

Suresh
Guest
Suresh

i am trying to insert form data from a jsp page to the mongodb but i am not succeed plz give me any example of jsp+mongodb with form submission please…..

Sankar
Guest
Sankar

Hi I did know how to set the data type as objectId in mongodb using java. Example “accountId” : ObjectId(“56c3fc7fbb82eeb4039106b7”). Give solution

Sankar
Guest
Sankar

It’s very urgent

Ashok
Guest
Ashok

After downloading MongoDriver 2.9.1, 2.10.1 and so on using maven, I cannot find MongoClient. Can you help me with this?

Ashok
Guest
Ashok

Never mind.. I got it after series of debugging and internet searches.. Thanks and the articles are really good for a newbie like me

Brija
Guest
Brija

Can you please share how did you do it?