Java Adapter Classes are special types of classes that allow developers to handle multiple types of events without having to implement every method in an event listener interface. Adapter classes are abstract classes that provide default implementations for all methods of an interface. These classes are used when developers want to handle only a subset of the methods of an interface, making their code cleaner and easier to manage.

The adapter classes are part of Java’s event-handling mechanism, which was introduced in 1995. Examples include the MouseAdapter and KeyAdapter classes, which provide default empty implementations of the methods in MouseListener and KeyListener interfaces, respectively. Developers can then override only the methods they need. Adapter classes have become a core feature in handling events within Java GUI programming. You can find more details in the Java documentation.

https://docs.oracle.com/javase/8/docs/api/java/awt/event/Adapter.html