The object passed to addActionListener() is instantiated from an anonymous class that implements the java.awt.event.ActionListener interface. Nested interfaces and classes.

📌 What is an Anonymous Class? An anonymous class is a local inner class without a name. It's used when you need to create a one-time-use subclass or implementation of an interface or abstract class.

You’ll also understand why many Java developers have adopted lambda expressions and method references as a cleaner, simpler alternative to anonymous classes. Note that code examples in this ...