Java is a statically-typed, object-oriented language that has powered enterprise backends since 1995 and is currently in its strongest decade in years. The Java 17 LTS and Java 21 LTS releases brought records, sealed classes, pattern matching, virtual threads (Project Loom), and dramatically faster startup with GraalVM native images.
The Spring ecosystem is still the default for new server applications: Spring Boot for HTTP services, Spring Data for persistence, Spring Security for auth, Spring Cloud for distributed-system primitives. The Quarkus and Micronaut frameworks compete for the same role with smaller memory footprints and faster startup, particularly on Kubernetes.
What you'll work with in these 54 courses
- Modern Java: records, sealed classes, pattern matching, virtual threads
- Spring Boot 3.x, Spring Data JPA, Spring Security, Spring Cloud
- Build tools: Maven, Gradle, dependency management, multi-module projects
- Persistence: Hibernate, JPA, JOOQ for SQL-first work
- Testing: JUnit 5, Mockito, Testcontainers, AssertJ
- Reactive programming: Project Reactor, RxJava, Spring WebFlux
Most enterprise backends in banking, insurance, telecom, and government still run Java. Outside finance: LinkedIn's API gateway, Netflix's microservice substrate, Twitter's search, the entire Android platform, and most of Apache Foundation infrastructure (Kafka, Cassandra, Spark, Hadoop).