Understanding Java class hierarchy. I’ve created an AccountDemo application class that lets you try out the Account class hierarchy. First, take a look at AccountDemo‘s source code.

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 ...

A public method should never be called by another public method within the same class hierarchy. It should only be called by other classes via the classes' public interface. Class calls might not be ...