1. Week 3 Recap CSE 115 – Spring 2007

2. Constructor Special capability of a class that sets up the initial state of the object. Constructor definitions are made up of: Constructor Header Constructor Body Starts with { and ends with }

3. Constructor Header Public identifier () public means as it did before. The identifier here is the name of the constructor. Java imposes that the name of a constructor is the same as the name of the class. () are called parameter list

4. Creating an object The syntax to create an object is: new ConstructorName(); new is a keyword that indicates that you will create a new instance of the class whose constructor is named after the keyword.

5. Instantiation Dependency Relationship Informally called “uses a” Represented in UML diagrams as a dotted arrow In code, if ClassA “uses a” ClassB: public class ClassA { public ClassA() { new ClassB(); }

6. Relationships Between Classes You should recognize the formal name, the informal name, the UML relationship arc, and the way the relationship looks in code.

7. Decoupling Separation of concerns Defining what an object can do, not how it does it

8. Interfaces One way to achieve decoupling in Java is through interfaces. An interface definition consists of an interface header and an interface body.

9. Interface Header public interface Name public: keyword – meaning the same as before interface: keyword – indicating the start of an interface definition Name: identifier – name of interface. Interface names by convention start off with a capital I, but then use same conventions as class names

10. Interface Body Enclosed in { } Contains what capabilities elements should have if they implement the interface.

11. Methods Formal specifications of capabilities inside our classes Method definitions consist of a method header and a method body

12. Method Definition (Method Header – Part 1) public type name() public: keyword – as before type: indication of the return type of the method – what information comes back from a method call? If no information comes back return type is void (another keyword)

13. Method Definition (Method Header – Part 2) public type name() name: identifier for method – method names follow conventions of class names, except the names begin with a lower case letter. (): called a formal parameter list – gives us a list of information that the method needs to finish its task.