Java How to Program, Early Objects, 11th Edition

10.10 Java SE 8 Interface Enhancements

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This section introduces interface features that were added in Java SE 8. We discuss these in more detail in later chapters.

10.10.1 default Interface Methods

Prior to Java SE 8, interface methods could be only public abstract methods. This meant that an interface specified what operations an implementing class must perform but not how the class should perform them.

As of Java SE 8, interfaces also may contain public default methods with concrete default implementations that specify how operations are performed when an implementing class does not override the methods. If a class implements such an interface, the class also receives the interface’s default implementations (if any). To declare a default ...