Goal : 인터페이스란 무엇인지 알아보고, 코드에서는 어떻게 구현되는지 알아본다. 인터페이스란? In Java, an interface is a blueprint or template of a class. It is much similar to the Java class but the only difference is that it has abstract methods and static constants. There can be only abstract methods in an interface, that is there is no method body inside these abstract methods. The class that implements the interface should be ab..