Connecting to MongoDB in Java

I'm following this tutorial to learn how to connect to MongoDB in Java, however, I'm encountering a problem and despite research, I can't seem to fix it. I do exactly what the tutorial tells me to do:

1. Create a new Java project
2. Add mongo-java-driver (I made sure I used the right one including the bson file, which seemed to be the problem in the other questions).
3. I create a new class and create a new MongoClient

This is my code up until now:

import com.mongodb.MongoClient;
import  com.mongodb.DB;


public class MongoDemo {

    public static void main(String[] args) {

        MongoClient mongoClient = new MongoClient("localhost", 27017);
        DB db = mongoClient.getDB("test");

    }

}

Now, I think the problem is with how I added the mongo-java-driver, since I get the following error in the first line: The import com.mongodb.MongoClient cannot be resolved but I can't seem to figure out how to fix that.

I did download the correct file and added it as an external library. When I type import com.mongodb. I do get a few suggestions, however, MongoClient is not one of them. What did I do wrong?

Solution 1:

You may be looking for something like this.

import com.mongodb.DB;
import com.mongodb.MongoClient;
import com.mongodb.ServerAddress;

public class MongoDemo {

    public static void main(String[] args) {
        ServerAddress serverAddress = new ServerAddress("http://localhost", 27017);
        MongoClient mongoClient = new MongoClient(serverAddress);
        DB db = mongoClient.getDB("test");
    }
}

When creating this, I created a maven project to manage the dependencies better and included the most recent MongoDB dependencies. Here's my POM.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>MongoDBExample</groupId>
    <artifactId>MongoDBExample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mongodb/mongo-java-driver -->
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongo-java-driver</artifactId>
            <version>3.7.0</version>
        </dependency>
    </dependencies>
</project>

I haven't tested this, however, notice how some of the code has changed. This is because some of the code used in the demo has been deprecated. This should be close.

Solution 2:

In addition to the Dale's answer:

this kind of error may occur due to incorrect addition of driver versions in POM. I recommend you to check properly POM file and try to change versions of mongodb java driver.

Also be attentive and careful with the connection of older and newer drivers, because there is the difference of syntax.

To connect to a standalone MongoDB instance (older drivers like 3.4):

MongoClient mongoClient = new MongoClient();

To connect to a standalone MongoDB instance (newer drivers like 3.8):

MongoClient mongoClient = MongoClients.create()

This difference may not be as noticeable, but adds further problems.