C Sc 335 Practice Test 1 Section Leader ________ Name ___________________________ 150 pts
1. Write the correct term, either "RESPONSIBILITIES" or "METHODS and DATA" in the blank space (2pts)
At the conceptual level, an object is a set of __________________________
At the implementation level, an object is a set of ___________________________
2. Describe the essence of polymorphism. (3pts)
3. List two Java structures that allow for polymorphic messages ____________ ___________ (2pts)
4. If you change ArrayList to LinkedList, will the following code still compile? true or false _____ (2pts)
List<String> list = new ArrayList<String>();
list.add("b");
list.add("a");
list.add("c");
Collections.shuffle(list);
5. Place an X by the name of any interfaces in the Java collection framework in the java.util package? (6pts)
___Collection
___ArrayList
___Queue
___Set
___Map
__SortedArrayList
6. Which goes into the top compartment (rectangle) of a class diagram of a single class? (2pts)
___Attributes(instance variables)
___Class Name
___Operations (methods)
7. Can one Java class implement more than one interface? yes or no ________ (2pts)
8. What is better, high cohesion or low cohesion? low or high ________ (2pts)
9. Write the output that appears when this code runs. (4pts)
ArrayList list = new ArrayList();
list.add(new
list.add(new
list.add(new
list.add(new
Integer(3));
Integer(5));
Integer(1));
Integer(4));
Iterator itr = list.iterator();
System.out.println(itr.hasNext());
System.out.println(itr.next());
System.out.println(itr.next());
System.out.println(itr.next());
1
10. Write the output that appears when this code runs. (5pts)
HashMap<Integer, List<String>> map = new HashMap<Integer, List<String>>();
List<String> one = new ArrayList<String>();
List<String> two = new LinkedList<String>();
one.add("A");
one.add("C");
two.add("B");
two.add("D");
map.put(1, one);
map.put(2, two);
System.out.println(map.get(0));
System.out.println(map.get(1));
System.out.println(map.get(2));
System.out.println(map.get(1).get(0));
System.out.println(map.get(2).get(1));
11. Write the output generated by the same code when aNumberMaybe is first "123" and then "NOgOOD" (6pts)
String aNumberMaybe = "123";
try {
System.out.println("--");
double num= Double.parseDouble(aNumberMaybe);
System.out.println("oo");
}
catch (NumberFormatException nfe) {
System.out.println("++");
}
String aNumberMaybe = "NOgOOD";
try {
System.out.println("--");
double num = Double.parseDouble(aNumberMaybe);
System.out.println("oo");
}
catch (NumberFormatException nfe) {
System.out.println("++");
}
12. List 3 differences between a Java interface and a Java abstract class
13. Finish this program with a graphical user interface that will allows use to enter text into a field and be told
whether or not that text represents a valid number. If the input is not a number, put !!ERROR in the middle.
Hint use Double.parseDouble(String) that throws an exception if the argumnet isn't a valid number. (15pts)
// Assume all imports exist
public class NumberFrame extends JFrame {
public static void main(String[] args) {
new NumberFrame().setVisible(true);
}
2
private JLabel heading = new JLabel("Enter a number below");
private JLabel myLabel;
private JTextField inputField;
public NumberFrame() {
setTitle("Numbers");
setSize(170, 100);
setDefaultCloseOperation(EXIT_ON_CLOSE);
myLabel = new JLabel("Nothing yet ...");
inputField = new JTextField();
add(heading, BorderLayout.NORTH);
add(myLabel, BorderLayout.CENTER);
add(inputField, BorderLayout.SOUTH);
14. The UofA Bookstore has decided that there is just too much traffic in the bookstore at the beginning of each
semester. In an effort to reduce in-house traffic, the bookstore has decided to implement an online storefront
where students can purchase all of their books online and just pick them up sometime after they’ve been purchased. You are to do some analysis and come up with a model for the bookstore’s new online front. User Stories:
o
o
o
o
o
o
o
A student may remove 1 to many items from the shelf and place them into a shopping basket
A student should be able to remove items from a shopping basket and place them back on the shelf
A student should be able to purchase the items in their shopping basket
To check out, a student must give their shopping basket to the cashier (there is only one cashier)
The cashier creates an order that consists of a item, quantity, and a price based on the item’s ISBN
If the CatCard has enough money then the total amount will be deducted and the items will be removed from
inventory, a claim check confirmation for the order will be sent to the student’s email address
If the CatCard funds are insufficient, place all back on the shelf
14 a) List the 5 most important objects to model this system along with the major responsibility: (10pts)
Candidate Object
Major Responsibility
3
14 b) Draw a UML class diagram showing all of your candidate objects and any relationships between them.
Show inheritance relationships, interface implementation, or general association such as dependency by drawing a
line. Write any multiplicity adornment you can think of. You will likely have 1, and or * in a few places at least.
Each classes needs the class name and at least one appropriate method (no attributes needed for a perfect score).
(12pts)
15. Given class Point and a test driver for class Circle and class Rectangle, implement a properly designed
inheritance hierarchy in Java (on the next page). Let Shape be the abstract class. Implement all three classes to
the right of the non-inheritance version on the next page. Completely implement all constructors and all methods.
Include all instance variables. The Circle and Rectangle classes must behave exactly the same with the
inheritance hierarchy as without. The assertions must pass. (20pts)
@Test
public void test getArea() {
// 10 pixels over, 10 pixels down, radius 2.0
Shape c = new Circle(10, 10, 2.0);
asssertEquals(3.14159, c.getArea(), 0.001);
// width = 3.25, height = 5.75
Shape r = new Rectangle(40, 10, 3.25, 5.75);
sssertEquals(18.6875, r.getArea(), 0.001);
Shape r2 = new Rectangle(40, 60, 2, 3);
asssertEquals(6.0, r.getArea(), 0.1);
}
}
4
public class Point {
private int xPos;
private int yPos;
// Use this type
Using good Object-Oriented Design, completely implement the hierarchy here
public Point(int x, int y) {
xPos = x;
yPos = y;
}
public int getX() {
return xPos;
}
public int getY() {
return yPos;
}
}
public class Rectangle {
private Point upperLeft;
private double width;
private double height;
public Rectangle(int x, int y,
double height, double width) {
upperLeft = new Point(x, y);
width = width;
height = height;
}
public int getX() {
return upperLeft.getX();
}
public int getY() {
return upperLeft.getY();
}
public double getArea() {
return width * height;
}
}
public class Circle {
private Point upperLeft;
private double radius;
public Circle(int x, int y,
double diameter) {
upperLeft = new Point(x,y);
radius = diameter / 2;
}
public int getX() {
return upperLeft.getX();
}
public int getY() {
return upperLeft.getY();
}
public double getArea() {
return Math.PI*Math.pow(radius, 2);
}
}
5
16 a) Same as Section Handout Using the Foo inheritance hierarchy, write a UML diagram of this
hierarchy to the right. Do not include the object class. The diagram must include all class names,
methods for each class, and arrows to indicate which class extends which. (6pts)
class Foo {
public void one() {
System.out.println("Foo1");
}
public void three() {
System.out.println("Foo3");
}
}
class Bar extends Foo {
public void one() {
System.out.println("Bar1");
}
public void two() {
System.out.println("Bar2");
one();
}
}
class Baz extends Foo {
public void one() {
System.out.println("Baz1");
super.three();
}
public void two() {
System.out.println("Baz2");
}
}
class Goo extends Bar {
public void one() {
super.one();
System.out.println("Goo1");
}
public void two() {
System.out.println("Goo2");
}
public void three() {
super.two();
System.out.println("Goo3");
}
}
16 b) For each blank line, write one of these three choices 16pts, 2 pts each)



The actual output if the code compiles and runs. Use / to indicate a new line.
CT (compile time) if an error would occur at compile time, or
RE (runtime error) if an error would occur while the program is running
6
Foo a = new Foo();
Foo b = new Baz();
Foo c = new Bar();
Bar d = new Goo();
Object e = new Baz();
b.one();
_________________________
c.one();
_________________________
c.two();
_________________________
e.one();
_________________________
((Baz)c).two();
_________________________
((Goo)d).three();
_________________________
((Foo)e).one();
_________________________
((Goo)((Foo)e)).one();
_________________________
17. The Command design pattern encapsulates the concept of a command into an object. You can save it for later
execution. In the following code, six commands of two different types are constructed and saved in a Vector.
Later on, the execute message is sent to all six Command objects. The two classes that you will be asked to write
are highlighted in boldface: Command and BorrowCommand. To save time, you do not need to write class
ReturnCommand.
// Have two borrowers and three books to store in the two Command objects
Borrower joe = new Borrower("Joe");
Borrower kim = new Borrower("Kim");
Book b0 = new Book("Pascal");
Book b1 = new Book("Java");
Book b2 = new Book("c++");
Command
Command
Command
Command
c1 = new BorrowCommand(joe, b0);
// Construct a Commmand so Joe borrows Pascal
c2 = new BorrowCommand(joe, b1);
// Construct a Commmand Joe borrows Java
c3 = new BorrowCommand(kim, b2);
//
...
c4ThatFails = new BorrowCommand(kim, b0); // Nothing will happen later with execute()
Command c5 = new ReturnCommand(joe, b0);
Command c6Fails = new ReturnCommand(joe, b2);
Output:
Joe has [] attempts to BORROW Pascal
[Joe has [Pascal], Kim has []]
List commandList = new Vector();
commandList.add(c1);
commandList.add(c2);
commandList.add(c3);
commandList.add(c4ThatFails); // already out
commandList.add(c5);
commandList.add(c6Fails); // Doesn't have
Joe has [Pascal] attempts to BORROW Java
[Joe has [Pascal, Java], Kim has []]
Kim has [] attempts to BORROW c++
[Joe has [Pascal, Java], Kim has [c++]]
Kim has [c++] attempts to BORROW Pascal
[Joe has [Pascal, Java], Kim has [c++]]
for(int j = 0; j < commandList.size(); j++) {
Command ref = (Command)commandList.get(j);
ref.execute();
System.out.println(borrowerList);
System.out.println();
}
Joe has [Pascal, Java] attempts to RETURN Pascal
[Joe has [Java], Kim has [c++]]
Joe has [Java] attempts to RETURN c++
[Joe has [Java], Kim has [c++]]
7
18a) Write interface Command as if it were in its own file (8pts)
18b) Complete class BorrowCommand as if it were in its own file. The execute method adjusts the Borrower
and the Book if everything is all right. However, if the Book is already borrowed, execute returns false. 18pts
// BorrowCommand attaches a specific book copy to a specific subscriber, both, the book
// copy’s and the subscriber’s objects are supplied by the programmer.
public class BorrowCommand implements Command {
protected Borrower theBorrower;
protected Book theBook;
public BorrowCommand(Borrower aBorrower, Book aBook) {
theBorrower = aBorrower;
theBook = aBook;
}
8
// When the Borrow button is clicked, execute this
public boolean execute() {
System.out.println(theBorrower + " attempts to BORROW " + theBook);
}
public boolean undo() { // a borrow by returning
System.out.println(theBorrower + " undo a Borrow" + theBook);
9