Compare inheritance and composition, the two fundamental ways to relate Java classes, then practice debugging ClassCastExceptions in Java inheritance.

Sealed classes in Java let developers limit the creation and use of subclasses and preserve the class hierarchy. Here is how sealed classes in Java work.

Why does Java's standard class library contain empty interfaces like Cloneable and Serializable? Find out why in this sixth installment in the "Object-oriented language basics" series.

There are benefits and drawbacks to Java's Iterator vs. ListIterator interface. Learn how to make the right choice when you choose between them.