Java™ How To Program (Early Objects), Tenth Edition

Section 10.10 Java SE 8 Interface Enhancements

• In Java SE 8, an interface may declare default methods—that is, public methods with concrete implementations that specify how an operation should be performed.

• When a class implements an interface, the class receives the interface’s default concrete implementations if it does not override them.

• To declare a default method in an interface, you simply place the keyword default before the method’s return type and provide a complete method body.

• When you enhance an existing an interface with default methods—any classes that implemented the original interface will not break—it’ll simply receive the default method implementations.

• With default methods, you can declare common method implementations ...