CSE 115 Lecture Notes - Lecture 22: List Of North American Broadcast Station Classes, Observer Pattern, Pattern Matching
12 Apr 2016
School
Department
Course
Professor
Document Summary
Which of the following is not represented in an object diagram: method, object, variable, reference answer: a. method. What is an interface good for? it introduces a type so you can have variable of type. No instantiation: interfaces can not be instantiated; we can not create an instance of. Menukeylistener in the example above because the method has no definition. A class can implement an interface: public class eventhandler implements actionlistener { A class which implements an interface is obligated to provide full definitions of all the methods specified in the interface. Our class now looks like: public class eventhandler implements actionlistener { @override public void actionperformed(actionevent e) { (or in more concrete form): public class eventhandler implements actionlistener { When you define a class, you are defining a type. When you define an interface, you are also defining a type.
