Run Cypher From Java

Are you a Java developer looking to take advantage of graphs and Neo4j?

There’s a new GraphAcademy course called Using Neo4j with Java, where you can learn how to integrate the Neo4j Java driver into your Java application.

Steps

The most common thing you will need to do when using Neo4j with Java is run a Cypher query and parse the results. The process is really simple:

1. Import the driver
2. Connect to a server
3. Verify the connection
4. Execute a Cypher query
5. Parse the results
6. Close the connection

Import the Driver

You’ll need to import the GraphDatabase and AuthTokens classes from the Neo4j driver package:

import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.AuthTokens;

public class App {
    public static void main(String[] args) {
        String NEO4J_URI = "bolt://localhost:7687";
        String NEO4J_USERNAME = "neo4j";
        String NEO4J_PASSWORD = "mypassword";

        // Create a new Neo4j driver instance

        // Verify the connection 

        // Execute a Cypher query

        // Parse the results

        // Close the connection

    }
}

Connect to a Server

Create an instance of the GraphDatabase.driverclass, passing your credentials:

// Create a new Neo4j driver instance
        var driver = GraphDatabase.driver(
                NEO4J_URI,
                AuthTokens.basic(
                    NEO4J_USERNAME,
                    NEO4J_PASSWORD)
            );

Verify the Connection

You can test the connection by calling the verifyConnectivity method:

// Verify the connection 
        driver.verifyConnectivity();

The driver will raise an exception if the connection cannot be made.

Execute a Cypher Query

The executableQuery method executes a Cypher query and returns the results:

// Execute a Cypher query
        var result = driver.executableQuery(
            "MATCH (c:Customer) RETURN c.name AS name, c.age AS age"
            ).execute();

Parse the Results

The executemethod fetches a list of records and loads them into memory:

// Parse the results
        var records = result.records();
        records.forEach(r -> {
            System.out.println(r.get("name"));
            System.out.println(r.get("age"));
        });

You can iterate through the records and use get to retrieve return values.

Close the Connection

Once you finish with the driver, call close to release any resources:

// Close the connection
        driver.close();

Here’s the complete code that makes a connection, executes a query, and parses the results:

import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.AuthTokens;

public class App {
    public static void main(String[] args) {
        String NEO4J_URI = "bolt://localhost:7687";
        String NEO4J_USERNAME = "neo4j";
        String NEO4J_PASSWORD = "mypassword";

        // Create a new Neo4j driver instance
        var driver = GraphDatabase.driver(
                NEO4J_URI,
                AuthTokens.basic(
                    NEO4J_USERNAME,
                    NEO4J_PASSWORD)
            );

        // Verify the connection 
        driver.verifyConnectivity();

        // Execute a Cypher query
        var result = driver.executableQuery(
            "MATCH (c:Customer) RETURN c.name AS name, c.age AS age"
            ).execute();

        // Parse the results
        var records = result.records();
        records.forEach(r -> {
            System.out.println(r.get("name"));
            System.out.println(r.get("age"));
        });

        // Close the connection
        driver.close();

    }
}

Learn More

You can learn more about how to use the Neo4j Java driver in the Using Neo4j with Java course on GraphAcademy.

The course will get you started developing Java applications with Neo4j and covers topics such as passing parameters to queries, dealing with graph data types, and managing transactions.

What Is Neo4j GraphAcademy?

Neo4j GraphAcademy offers a variety of courses completely free of charge, teaching everything from Neo4j Fundamentals to Building Knowledge Graphs With LLMs and much more.

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Run Cypher From Java was originally published in Neo4j Developer Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.