Java quick start

At the end of this guide, you will have created a simple Java console Hello, World! program that connects to the Memgraph database and executes simple queries.

Prerequisites

For this guide you will need:

• A running Memgraph instance. If you need to set up Memgraph, take a look at the Installation guide.
• A basic understanding of graph databases and the property graph model.
• Java 8 or 11 installed.

Basic Setup

We'll be using Eclipse IDE 2020-09 on Windows 10 to connect a simple Java console application to a running Memgraph instance using Maven. If you're using a different IDE, the steps might be slightly different, but the code is probably the same or very similar.

Let's jump in and connect a simple program to Memgraph.

1. Open Eclipse and create a new Maven project.
2. Select the Create a simple project option.
3. For the Group Id field put com.memgraph.app and for Artifact Id put my-app. Afterwards, click the Finish button.
4. Open the pom.xml file and add the following dependency:

<dependencies>
    <dependency>
      <groupId>org.neo4j.driver</groupId>
      <artifactId>neo4j-java-driver</artifactId>
      <version>4.1.1</version>
    </dependency>
  </dependencies>

5. Create the HelloWorld.java program and copy the following code:

import org.neo4j.driver.AuthTokens;
import org.neo4j.driver.Driver;
import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.Session;
import org.neo4j.driver.Result;
import org.neo4j.driver.Transaction;
import org.neo4j.driver.TransactionWork;

import static org.neo4j.driver.Values.parameters;

public class HelloWorld implements AutoCloseable
{
    private final Driver driver;

    public HelloWorld( String uri, String user, String password )
    {
        driver = GraphDatabase.driver( uri, AuthTokens.basic( user, password ) );
    }

    public void close() throws Exception
    {
        driver.close();
    }

    public void printGreeting( final String message )
    {
        try ( Session session = driver.session() )
        {
            String greeting = session.writeTransaction( new TransactionWork<String>()
            {
                @Override
                public String execute( Transaction tx )
                {
                    Result result = tx.run( "CREATE (a:Greeting) " +
                                                     "SET a.message = $message " +
                                                     "RETURN 'Node ' + id(a) + ': ' + a.message",
                            parameters( "message", message ) );
                    return result.single().get( 0 ).asString();
                }
            } );
            System.out.println( greeting );
        }
    }

    public static void main( String... args ) throws Exception
    {
        try ( HelloWorld greeter = new HelloWorld( "bolt://localhost:7687", "", "" ) )
        {
            greeter.printGreeting( "Hello, World!" );
        }
    }
}

Once you run the program, you should see an output similar to the following:

Node 1: Hello, World!

Where to next?

For real-world examples of how to use Memgraph, we suggest you take a look at the Tutorials page. You can also browse through the Database functionalities section to get an overview of all the functionalities Memgraph offers.