Have a look through a collection of focused series on various Java development topics.

Learn Spring Boot

Learn Spring Boot, from the core concepts to the advanced scenarios you can implement with the framework. >>>

Vavr Tutorial

Vavr is a functional library for Java 8+ that provides immutable data types and functional control structures. >>>

Spring Data MongoDB Tutorial

This is a guide to Spring Data MongoDB – from a quick intro on how to hit the ground running in a Spring project, to queries and more complex features. >>>

Jackson JSON Tutorial

Learn Jackson 2 inside out – the marshalling and the unmarshalling from basic mapping to advanced techniques and exceptions. >>>

HttpClient 4 Tutorial

Comprehensive Guide to the Apache HttpClient – start with basic usage and make your way though the advanced scenarios. >>>