Tuesday, 8 April 2014

MongoDB Introduction with Java

What is MongoDB?
MongoDB is a non-relational database management system unlike traditional relational database management systems like Oracle, MySQL, IBM DB2 etc. MongoDB comes under NoSQL category. This is an open source document store database where you can store documents in JSON format.

This post can help you setting up mongo DB in your windows environment and also take you through the steps to connect mongo DB using Java program. Below points will be covered in this post:·      
  • How to install MongoDB?
  • How to Use MongoDB ?
  • How to Access MongoDB in Java?
How to install MongoDB?
Installing and setting up MongoDB is pretty simple. You just need to download zip/tar file, extract it, setup database directory location, that’s it. Isn’t it pretty simple? Off course it is. 

A.     Download MongoDB Distribution
Download MongoDB from here. If you are using Windows 64 bit, you can download this.

B.     Extract Zip File
Extract the downloaded zip file at your desired location (say < MongoDB_DIR >). Once you extract the zip file, you will see below files under ‘<MongoDB_DIR>/bin’ directory. 

C.     Setup Default Directory
This is the time to create directory where MongoDB will store the database documents. Create below directories under ‘<MongoDB_DIR>/bin’ folder.


That’s it, you are done with installation and setting up the MongoDB.  Now, I believe you must be excited to see how to use this MongoDB. Let’s move to next section ‘How to Use MongoDB’.

How to Use MongoDB?
MongoDB can be accessed using client 'Mongo Shell'. MongoShell connects to the server where MongoDB is installed and then you can perform CRUD operations on MongoDB using 'Mongo Shell'.  

A.     Start MongoDB
Start the MongoDB using below command.

<MongoDB_DIR>/bin>mongod --dbpath ./data/db

Notice that ‘/data/db’ is same directory which we have created in last section.  If you want to get details of different commands you can execute below command.

<MongoDB_DIR>/bin>mongod --help

B.     Open Mongo Shell
Start Mongo shell using below command. Once the Mongo shell is started, you are ready to perform operations on MongoDB.


By default Mongo shell connects to the database which is running on ‘localhost:27017’. You can also connect to the database by providing host and port.

<MongoDB_DIR>/bin>mongo.exe <host>/port

Notice that default data base is ‘test’. That means whatever operations you will perform on MongoDB, these will be performed on ‘test’ database. In case you want to use your own database you can execute below command:

use <your_db>

This command will create your database (if does not exist) and then you can perform operations on your database.

C.     Perform MongoDB Operations

Now your MongoDB and MongoShell both are running. Refer below screen shot to execute different commands using MongoShell on MongoDB.

If you are interested to get more details on MongoDB operations, you can refer this. 

How to Access MongoDB in Java?
Using MongoDB Java Driver you can perform MongoDB operations in Java. If you are using Maven you can configure below dependency in your project to access the mongo-java-driver’s API. These APIs work as client to connect MongoDB and perform database operations.


If you directly want to download mongo-java-driver binary distribution, you can download it from here.

Java MongoDB Communication Flow
This diagram depicts the communication flow between Java and MongoDB.   

Creating Java Class to Perform MongoDB CRUD Operations

This class demonstrates how to perform MongoDB crud operations. You can directly import this class into your project and execute it. Ensure to start MongoDB before executing this class.

package com.tengen.crud;

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.MongoClient;
 * Class performs MongoDB CRUD Operations
public class MongoDBOperations {
        public static void main(String[] args) throws UnknownHostException {

               MongoClient mongoClient = new MongoClient();
               //Connect to Mongo DB 'test'
               DB database = mongoClient.getDB("test");
               //Get 'Employee' collection, If it does not exist, this will be created
               DBCollection dbCollection = database.getCollection("employee");
               List<String> names =

               System.out.println("Inserting documents...");
               // [Create Document] Insert employee documents
               for (String name : names) {
                       dbCollection.insert(new BasicDBObject("name", name));

               // [Update Document] Update the document 
               // Add 'age' and 'email' properties in the document where name = 'Narendra']
               dbCollection.update(new BasicDBObject("name""Narendra"),
                              new BasicDBObject("age", 30).append("email",    
               // [Update Document] Perform upsert (update or insert)
               // Add 'gender' property in the document where name = 'Vivek']
               dbCollection.update(new BasicDBObject("name""Vivek"),
                              new BasicDBObject("$set"new BasicDBObject("gender""M")),
               System.out.println("After Updating document ...");
               //[Remove/Delete Document] Remove Document [where name = 'Shashank']
               dbCollection.remove(new BasicDBObject("name""Shashank"));
               System.out.println("After removing document...");
               // If you want to drop/remove the collection, uncomment below statement
               // dbCollection.drop();              
        private static void print(DBCollection dbCollection){
               // [Read Document] Read and print all documents            
               DBCursor cursor = dbCollection.find();
               try {
                       while (cursor.hasNext()) {
               } finally {

If this program successfully connects to the MongoDB, you must see the blow console output

Inserting documents...
{ "_id" : { "$oid" : "5343707eddff0714f85b8923"} , "name" : "Narendra"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8924"} , "name" : "Vinay"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8925"} , "name" : "Ajit"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8926"} , "name" : "Ranveer"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8927"} , "name" : "Shashank"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8928"} , "name" : "Vivek"}
After Update ...
{ "_id" : { "$oid" : "5343707eddff0714f85b8924"} , "name" : "Vinay"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8925"} , "name" : "Ajit"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8926"} , "name" : "Ranveer"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8927"} , "name" : "Shashank"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8923"} , "age" : 30 , "email" : "narendra.verma@gmail.com"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8928"} , "gender" : "M" , "name" : "Vivek"}
After removing document...
{ "_id" : { "$oid" : "5343707eddff0714f85b8924"} , "name" : "Vinay"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8925"} , "name" : "Ajit"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8926"} , "name" : "Ranveer"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8923"} , "age" : 30 , "email" : "narendra.verma@gmail.com"}
{ "_id" : { "$oid" : "5343707eddff0714f85b8928"} , "gender" : "M" , "name" : "Vivek"}

If you reached at this stage and played with MongoDB, you can feel proud that you have added one more skill in your skill repository. If this post really helped you, your comments are most welcome. Also, I am looking forward for your valuable suggestions to improve my blog posts.

!! Happy MongoDB Learning !!