1. Chapter 7 Java Object Model

2. Types
Type: set of values and the operations that can be applied to the values
Strongly typed language: compiler and run-time system check that no operation can execute that violates type system rules
Compile-time check Employee e = new Employee(); e.clear(); // ERROR
Run-time check:

3. Java Types
Primitive types: int short long byte char float double boolean
Class types
Interface types
Array types
The null type
Note: void is not a type

4. Java Values value of primitive type reference to object of class type
reference to array
null
Note: Can't have value of interface type

5. Subtype Relationship S is a subtype of T if S and T are the same type
S and T are both class types, and T is a direct or indirect superclass of S
S is a class type, T is an interface type, and S or one of its superclasses implements T
S and T are both interface types, and T is a direct or indirect superinterface of S
S and T are both array types, and the component type of S is a subtype of the component type of T
S is not a primitive type and T is the type Object
S is an array type and T is Cloneable or Serializable
S is the null type and T is not a primitive type

6. Type Inquiry Test whether e is a Shape: if (e instanceof Shape) . . .
Common before casts: Shape s = (Shape) e;
Don't know exact type of e
Could be any class implementing Shape
If e is null, test returns false (no exception)

7. The Class Class getClass method gets class of any object
Returns object of type Class
Class object describes a type
Object e = new Rectangle(); Class c = e.getClass(); System.out.println(c.getName());
// prints java.awt.Rectangle

8. The equals Method equals tests for equal contents
== tests : whether two references are the identical objects.
Used in many standard library methods

9. Requirements for equals Method
reflexive: x.equals(x)
symmetric: x.equals(y) if and only if y.equals(x)
transitive: if x.equals(y)  and y.equals(z), then x.equals(z)
x.equals(null) must return false

10. Chapter 8 Frameworks

11. Frameworks Set of cooperating classes
Structures the essential mechanisms of a problem domain
Example: Swing is a GUI framework
Framework != design pattern
Typical framework uses multiple design patterns

12. Application Frameworks
Implements services common to a type of applications
Programmer forms subclasses of framework classes
Result is an application
Inversion of control: framework controls execution flow

13. Applets Applet: Java program that runs in a web browser
Programmer forms subclass of Applet or JApplet
Overwrites init/destroy start/stop paint

14. Applets

15. Applets Interacts with ambient browser getParameter showDocument
HTML page contains applet tag and parameters <applet code="BannerApplet.class" width="300" height="100"> <param name="message" value="Hello, World!"/> <param name="fontname" value="Serif"/> <param name="fontsize" value="64"/> <param name="delay" value="10"/> </applet>

16. Example Applet Shows scrolling banner init reads parameters
start/stop start and stop timer
paint paints the applet surface
Ch8/applet/BannerApplet.java

17. Example Applets

18. Applets as a Framework Applet programmer uses inheritance
Applet class deals with generic behavior (browser interaction)
Inversion of control: applet calls init, start,stop,destroy