What are the technologies to learn for a Java backend developer?

A Java backend developer typically works with the following technologies:

1. Java SE (Standard Edition) or Java EE (Enterprise Edition) for building the backend application.
2. Spring Framework, which is a popular framework for building Java applications. It provides features for dependency injection, data access, web services, and more.
3. Hibernate, an Object-Relational Mapping (ORM) framework that allows you to interact with a database using Java objects.
4. RESTful web services for building web services that can be consumed by clients.
5. Git or SVN for version control.
6. Maven or Gradle for building and managing dependencies.
7. Relational databases such as MySQL, Oracle, or PostgreSQL for storing data.
8. Experience with UNIX/Linux commands for server deployment.

Some other technologies that could be helpful to know :

• Experience with Containers and container orchestration like Docker and Kubernetes.
• Knowledge of Caching mechanisms like Redis, Memcached
• Familiarity with any of the Cloud platform like AWS, GCP, Azure

However, the specific set of technologies used will depend on the company and project.