To start, take a look at this diagram of Java class loaders interacting in a Java program. IDG. ... The level of visibility depends on the class loader hierarchy and the classpath, ...

Figure 1 shows a UML class diagram for the simple class and type hierarchy used as this article’s example. The diagram models two classes, one interface, and three type declarations.

Sealed classes, proposed in JEP 409 and available since Java 17, let developers limit and control how deeply a component's type hierarchy can extend. With sealed classes, a developer can essentially ...