In the previous chapter, we covered several enhancements for the modern Java platform. These enhancements represented a wide range of tools and updates to APIs to make developing with Java easier, with greater optimization possibilities for our Java applications. We looked at the new HTTP client, changes to Javadoc and the Doclet API, the new JavaScript parser, JAR and JRE changes, the new Java-level JVM compiler interface, new support for TIFF images, platform logging, XML catalog support, collections, and the new platform-specific desktop features. We also looked at enhancements to method handling and the deprecation annotation.

In this chapter, we will cover concurrency enhancements for the Java platform. Our primary focus will be on the support for reactive programming, a concurrency enhancement that is provided by the Flow  class API. Reactive programming was first released in Java 9 and remains an important feature of Java 10 and 11. We will also explore additional concurrency enhancements.

More specifically, we will cover the following topics:

• Reactive programming
• The Flow API
• Additional concurrency updates
• Spin-wait hints