Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.
Is ObjectDB better than Object Relational Mapping (ORM)?
As noted above, using ObjectDB instead of a relational database and ORM combination is easier and leads to better performance. ORM tools, however, are very useful where the use of a relational database is mandatory (e.g. as a result of a customer request or when a new application is developed for an existing old relational database).
By using the Java Persistence API (JPA), you can develop portable applications that can use both ObjectDB and relational databases. This way you have the best of both worlds - use ObjectDB when applicable for faster development and better performance and use a JPA ORM provider (Hibernate, TopLink, EclipseLink or DataNucleus) to access relational databases when necessary - with exactly the same code.