The tricky part of Neo4j is learning to work with its Cypher Query Language, which requires thinking graphically. Once you've got that down, writing a Java application that integrates with your Neo4j data store is easy.
Java development frameworks can help developers get an application up and running faster, offering code reuse and eliminating the task of building boilerplate code
Enterprises are figuring out that they likely need different database engines to power different parts of their applications. AWS has figured that out, too