Chapter 8 8.7-End

7	Open the dome-v2 project. Add a class for video games to the project. Create some video game objects and test that all the methods work as expected.	Done, here are the class' fields:
8	Order these items into an inheritance hierarchy: apple, ice cream, bread, fruit, food-item, cereal, orange, dessert, chocolate mousse, baguette.	Done:
9	In what inheritance relationship might a touch pad and a mouse be?	Computer Devices
10		Rectangle would be the parent class of square, as a square is a rectangle, but a rectangle is not a square, simply that.
11	Assume we have four classes: Person, Student, Teacher & PhDStudent. Teacher and Student are both subclasses of Person. PhDStudent is a subclass of Student. Which of the following assignments are legal and why? Person p1 = new Student(); Person p2 = new PhDStudent(); PhDStudent phd1 = new Student(); Teacher t1 = new Person(); Student s1 = new PhDStudent(); s1 = p1; s1 = p2; p1 = s1; t1 = s1; s1= phd1; phd1 = s1;	a) legal b) legal e) legal g) legal h) legal j) legal k) legal because sub-types can be assigned to super classes, or to their own class, but super classes can't be assigned to sub-classes, it's like saying a square gets new rectangle, it's preposterous.
12	Test your answers to the previous question by creating the classes mentioned in that exercise, and trying it out in BlueJ.	Done, this is the set up i used:
13	What has to change in the Database class when another item subclass (for example class VideoGame) is added? Why?	Nothing, because VideoGame is an Item, and therefore Item will allow VideoGame to be added to the ArrayList of Database without further coding.
14	Use the documentation of the standard class libraries to find out about the inheritance hierarchy of the collection classes. Draw a diagram showing the hierarchy. http://java.sun.com/j2se/1.4.2/docs/api/	Unable to find the section on standard class libraries.
15	Go back to the lab-classess project from chapter 1. Add instructors to the project. Use inheritance to avoid code duplication between students and instructors.	I attempted to add some methods to the project as well but received some compiling errors:
16	Draw an inheritance hierarchy representing parts of a computer system (processor, memory, disk drive, CD drive, printer, scanner, keyboard, mouse, etc.)
17	Look at the code below. You have four classes (O,X,T and M) and a variable of each of these. O o; X x; T t; M m; The following assignments are all legal. m = t; m = x; o = t; The following assignments are all illegal. o = m; o = x; x = o; What can you say about the relationships of these classes?	They have no relationships, therefore it makes no sense whatsoever to assign them to one another.
18	Draw an inheritance hierarchy of AbstractList and all its (direct and indirect) subclasses, as they are defined in the Java standard library. http://java.sun.com/j2se/1.4.2/docs/api/	Done: