Sealed and Hidden Classes

This chapter includes 13 problems covering sealed and hidden classes. The first 11 recipes will cover sealed classes, a very cool feature introduced in JDK 17 (JEP 409) to sustain closed hierarchies. The last two problems cover hidden classes, a JDK 15 (JEP 371) feature that allows frameworks to create and use runtime (dynamic) classes hidden in the JVM’s internal linkages of bytecode, and to the explicit usage of class loaders.

You’ll be skilled in both topics by the end of this chapter.