In Java 101: Inheritance in Java, Part 1, you learned how to leverage inheritance for code reuse, by establishing is-a relationships between classes.Composition is a closely related programming ...

For example, a Java program obtains file I/O (input/output) services by creating objects from various file-related classes in Java’s class library and calling their methods.

Sealed classes make Java an even more powerful and expressive language and set the stage for even more sophisticated techniques such as pattern matching, which we'll explore in a subsequent article. A ...