代写Project_1234567890
Project Requirements
Create a new Eclipse workspace named "Project_1234567890" on the desktop of your computer (replace
1234567890 with your student ID number). For each question below, create a new project in that workspace. Call
each project by its question number: "Question1", "Question2", etc. If you do not remember how to create a
workspace or projects, read the "Introduction to Eclipse" document which is on iSpace. Answer all the questions
below. At the end of the project, create a ZIP archive of the whole workspace folder. The resulting ZIP file must be
called "Project_1234567890.zip" (replace 1234567890 with your student ID number). Upload the ZIP file
on iSpace.
Here are a few extra instructions:
• Give meaningful names to your variables so we can easily know what each variable is used for in your program.
• Put comments in your code (in English!) to explain WHAT your code is doing and also to explain HOW your
program is doing it. Also put comments in your tests.
• Make sure all your code is properly indented (formatted). Your code should be beautiful to read.
Failure to follow these instructions will result in you losing points.
Question 1
In this project you need to write a book lending system for a Library. The system has different roles for registered
users. There are two types of user roles: borrower and lender.
Write an IUser interface for library users, with the following UML specification:
+----------------------------------+
| <> |
| IUser |
+----------------------------------+
| + getName(): String |
| + getBook(): int |
| + moreBook(int number): void |
+----------------------------------+
and a User class that implements IUser and has the following UML specification:
+-----------------------------------+
| User |
+-----------------------------------+
| - name: String |
| - book: int |
+-----------------------------------+
| + User(String name, int book) |
| + getName(): String |
| + getBook(): int |
| # setBook(int book): void |
| + moreBook(int number): void |
| + testUser(): void |
+-----------------------------------+
The name instance variable indicates the user name. The book instance variable indicates the number of books
borrowed by the user.
The setBook method changes the number of books borrowed by the user. The setBook method is protected,
not public. This means that only subclasses of the User class can use the setBook method. All the other classes
in the system cannot use the setBook method, so they cannot change the number of books borrowed by a user.
The purpose of the moreBook method is to increase the number of books borrowed or lent by the user (depending
on what kind of user it is) by the number given as argument to the method. The moreBook method of the User
class is abstract, since we do not know what kind of role the user is (a borrower borrows books from other users
and a lender lend books to other users).
Also add to your program a Test class to test your User class.
public class Test {
public static void main(String[] args) {
User.testUser();
}
}
Question 2
Add a class Lender that extends User. The constructor of the Lender class takes as arguments a name and the
number of books lent by the user. The Lender class does not have any instance variable.
Warning: the constructor of the Lender class takes as argument the number of books lent by the lender, but the
book instance variable of the User class indicates how many books the user borrowed! Lending books is the same
as borrowing a negative number of books.
The moreBook method of the Lender class increases the number of books lent by the lender user by the number
given as argument to the method (so the books borrowed by the lender becomes more negative!)
Make sure you test all the methods of your new Lender class using testLender method.
Here are some tests for your new Lender class:
public static void testLender()
{
Lender l = new Lender("Anna",5);
System.out.println(l.getName() == "Anna");
System.out.println(l.getBook() == -5);
l.setBook(-6);
System.out.println(l.getBook() == -6);
l.moreBook(2);
System.out.println(l.getBook() == -8);
l.moreBook(-9);
System.out.println(l.getBook() == 1);
}
Also, do not forget to modify your Test class to test the Lender class.
Question 3
Add a class Borrower that extends User. The constructor of the Borrower class takes a name and a number of
books borrowed by the borrower. If the number of books given as argument is strictly less than zero, then the
constructor must throw a NotALenderException with the message "A new borrower cannot lend
books.". The borrower class does not have any instance variable.
The moreBook method of the Borrower class increases the number of books borrowed by the borrower by the
number of books given as argument to the method (so the books borrowed by the borrower becomes more positive!)
For example, if a borrower currently borrows 10 books and moreBook(2) is called then the borrower borrows 12
books. It is fine for the moreBook method to be given a negative value as argument, which means the borrower
then just returned some books. For example, if a borrower currently borrows 10 books and moreBook(-2) is
called then the borrower borrows 8 books.
However, a borrower cannot lend books, so the number of books borrowed by the borrower must always be positive
or zero, never negative. If the argument given to the moreBook method is too negative and would change the book
variable into a negative value, then the number of books borrowed by the borrower must not change and the
moreBook method must throw a NotALenderException with the message “A borrower cannot lend
XXX book(s).”, where XXX is replaced with the result of -(book + number).
For example, if a borrower currently borrows 10 books and moreBook(-12) is called then the borrower still
borrows 10 books and the method throws a NotALenderException with the message “A borrower
cannot lend 2 book(s).”.
Note: to simplify the project, do not worry about the setBook method.
Change other classes and interfaces as necessary.
Make sure you test your new Borrower class, including inherited methods. Here are some tests for your new
Borrower class:
public static void testBorrower()
{
try
{
Borrower b = new Borrower("Bob",-1);
} catch(NotALenderException e)
{
System.out.println(e.getMessage().equals("A new borrower cannot lend
books."));
}
try
{
Borrower b = new Borrower("Bob",10);
System.out.println(b.getName()=="Bob");
System.out.println(b.getBook()==10);
b.setBook(5);
System.out.println(b.getBook()==5);
b.moreBook(2);
System.out.println(b.getBook()==7);
b.moreBook(-2);
System.out.println(b.getBook()==5);
b.moreBook(-5);
System.out.println(b.getBook()==0);
b.moreBook(-1);
} catch(NotALenderException e)
{
System.out.println(e.getMessage().equals("A borrower cannot lend 1
book(s)."));
}
}
Also, do not forget to modify your Test class to test the Borrower class.
Question 4
Add a Library class with the following UML specification:
+-------------------------------------------+
| Library |
+-------------------------------------------+
| - name: String |
| - users: ArrayList |
+-------------------------------------------+
| + Library(String name) |
| + addUser(IUser user): void |
| + totalBorrowedBooks(): int |
| + getBook(String name): int |
| + moreBook(String name, int number): void |
| + testLibrary(): void |
+-------------------------------------------+
When a library is created, it has an arraylist of users (IUser) but the arraylist is empty (the arraylist does not
contain any user).
The addUser method takes a user (IUser) as argument and adds the user to the arraylist of users for the library.
The totalBorrowedBooks method returns as result the total number of books borrowed by all users of the
library (the result can be either positive or negative).
The getBook method takes as argument the name of a user and returns as result the number of books currently
borrowed by the user. If the library does not have a user with the given name, then the getBook method must
throw an UnknownUserException with the message "User XXX unknown.", where XXX is replaced with
the name of the user. Do not worry about multiple users having the same name. You can assume all user names are
unique in the arraylist.
The moreBook method takes as argument the name of a user and a number of books and changes the number of
books currently borrowed by that user. If the library does not have a user with the given name, then the moreBook
method must throw an UnknownUserException with the message "User XXX unknown.", where XXX is
replaced with the name of the user. Do not worry about multiple users having the same name.
Note: the moreBook method does not catch any exception, it only throws exceptions.
Hint: use the equals method to compare strings, not the == operator which only works with constant strings.
Make sure you test your new Library class in testLibrary method. Here are some tests for your new
Library class:
public static void testLibrary() {
Library li = new Library("UIC Library");
System.out.println(li.totalBorrowedBooks() == 0);
li.addUser(new Lender("L1", 10));
try {
System.out.println(li.getBook("L1") == -10);
System.out.println(li.totalBorrowedBooks() == -10);
li.addUser(new Borrower("B1", 20));
System.out.println(li.getBook("L1") == -10);
System.out.println(li.getBook("B1") == 20);
System.out.println(li.totalBorrowedBooks() == 10);
li.getBook("B2");
} catch(UnknownUserException ex) {
System.out.println(ex.getMessage().equals("User B2 unknown."));
} catch(NotALenderException ex) {
// This should never happen!
System.out.println(false);
}
//More test cases are needed…
……
……
……
}
Also, do not forget to modify your Test class to test the Library class.
Question 5
In this question and the next one we want to create a command line interface (CLI) for our Library book lending
system.
Add a CLI class with a main method. Your code then has two classes with a main method: the Test class that you
can use to run all your tests for all your classes, and the CLI class that you will now use to run the interactive textbased interface of your program.
The CLI class does not have any testCLI method because this class is only used to allow users to use the system
interactively.
Add to the CLI class a private static input instance variable which is a Scanner object that reads input from the
standard input stream System.in:
private static Scanner input = new Scanner(System.in);
Always use this input scanner object when you need to read input. (Never close this scanner object, because this
would also close the standard input stream System.in, and then the next time you tried to read something from
the standard input stream you would get a NoSuchElementException!)
In addition to the main method and the input instance variable, the CLI class has two methods called
readLine and readPosInt.
The readLine method is static and private, it takes a string as argument, and returns another string as result. The
readPosInt method is static and private, it takes a string as argument, and returns a positive integer as result.
The readLine method uses System.out.print (not println) to print its string argument on the screen
(later when we use the readLine method, the string argument of the method will be a message telling the user to
type some text). Then the readLine method uses the input scanner object to read a whole line of text from the
user of the program and returns the text as result.
The readPosInt method uses System.out.print (not println) to print its string argument on the screen
(later when we use the readPosInt method, the string argument of the method will be a message telling the user to
type some integer). Then the readPosInt method uses the input scanner object to read an integer from the
user of the program.
After reading the integer, the readPosInt method must also use the scanner’s nextLine method to read the
single newline character that comes from the user pressing the Enter key on the keyboard after typing the integer
(if you do not read this newline character using the nextLine method inside the readPosInt method, then the
newline character will remain in the input stream, and, the next time you use the readLine method described
above, the readLine method will just immediately read only the newline character from the input stream and
return an empty string as result, without waiting for the user to type anything!)
If the user types something which is not an integer, then the nextInt method of the scanner will throw an
InputMismatchException. In that case the code of your readPosInt method must catch the exception, use
System.out.println to print the error message "You must type an integer!" to the user (use
System.out.println for this, not System.err.println, otherwise you might hit a bug in Eclipse...), use
the scanner’s nextLine method to read (and ignore) the wrong input typed by the user of the program (if you do
not do this, the wrong input typed by the user will remain in the input stream, and the next time you call the
nextInt method again, you will get an InputMismatchException again!), and then do the whole thing again
(including printing again the string argument of the readPosInt method) to try to read an integer again (hint: put
the whole code of the method inside a while loop).
After reading the integer and the newline character (which is just ignored), the readPosInt method tests the
integer. If the integer is bigger than or equal to zero, then the readPosInt method returns the integer as result. If
the integer is strictly less than zero, then the readPosInt method uses System.out.println to print the
error message "Positive integers only!" to the user (use System.out.println for this, not
System.err.println, otherwise you might hit a bug in Eclipse...), and then does the whole thing again
(including printing again the string argument of the readPosInt method) to try to read an integer again (hint: just
print the error message, and then the while loop you already have around the whole code will automatically do
the whole thing again...)
For example, if you want to check that your two methods readLine and readPosInt work correctly, put the
following code in the main method of your CLI class:
public static void main(String[] args) {
String str1 = readLine("Type some text: ");
System.out.println("Text read is: " + str1);
int i = readPosInt("Type an integer: ");
System.out.println("Integer read is: " + i);
String str2 = readLine("Type some text again: ");
System.out.println("Text read is: " + str2);
}
then running the main method of the CLI class should look like this (where aaaa bbbb, cccc, dddd eeee, -
100, -200, 1234, and ffff gggg are inputs typed by the user on the keyboard):
Type some text: aaaa bbbb
Text read is: aaaa bbbb
Type an integer: cccc
You must type an integer!
Type an integer: dddd eeee
You must type an integer!
Type an integer: -100
Positive integers only!
Type an integer: -200
Positive integers only!
Type an integer: 1234
Integer read is: 1234
Type some text again: ffff gggg
Text read is: ffff gggg
Question 6
Once you have checked that your methods readLine and readPosInt work correctly, remove all the code
inside the main method of the CLI class so that the main method is empty again.
In the rest of this question, use the readLine and readPosInt methods every time your program needs to read
a string or an integer from the user.
In the empty main method of the CLI class, create a single Library object with the name "UIC Library".
The main method of the CLI class must then print a menu that allows the user of your system to do six different
actions that involve the library object, and your program must then read an integer from the user that indicates
which action must be performed by the program (see below for the details about each action). Use the
readPosInt method to print the menu (give the string for the menu as the argument of readPosInt) and to
read the integer typed by the user.
For example, the menu should look like this:
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
The user then types an integer between 1 and 6 to select the action.
For example (where 3 is an input from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
and your program then performs the selected action.
After an action has been performed by your program, your program must again print the menu and ask again the
user of the program for the next action to perform (hint: put the whole code of the main method inside a while
loop, except for the one line of code that creates the single library object).
If the user types an integer which is not between 1 and 6, then your program must print an error message
"Unknown action!" to the user (hint: when testing the integer for the action, use the default case of a
switch statement) and then print the menu again (by just going back to the beginning of the while loop).
For example (where 7 is an input from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 7
Unknown action!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
If the user types something which is not an integer, the readPosInt method that you implemented in the
previous question will automatically repeat the menu and ask the user to type an integer again until the user actually
types an integer, so you do not have to worry about this in the code of the main method of your CLI class.
For example (where aaaa and bbbb are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): aaaa
You must type an integer!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): bbbb
You must type an integer!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Here are the detailed explanations for each action.
Action 1: printing the total number of books borrowed by all users.
When the user of the system specifies action 1, your program must simply print on the screen the total number of
books currently borrowed by all users of the library. Then your program goes back to printing the menu of actions
(by just going back to the beginning of the while loop).
For example (where 1 is an input from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 1
Total number of borrowed books: 50
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Action 2: adding a new user to the library.
When the user of the software specifies action 2, your program must add a new user to the library. To add a new
user, your program needs to ask the user three things: the role of user (an integer read using readPosInt: the
integer 1 represents lender, the integer 2 represents borrower, any other integer must result in an error message
"Unknown user role!" being printed and the software going immediately back to the main menu), the name
of the user (a string read using readLine), and the initial number of books that the user lends (for a lender) or
borrows (for a borrower). You program must then create the correct user, add it to the library, and print an
information message. The program then goes back to the menu.
For example (where 2, 3, 2, 1, Anna, 5, 2, 2, Bob, and 10 are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 3
Unknown user role!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 1
Enter the name of the user: Anna
Enter the initial number of borrowed books: 5
Lender "Anna" lending 5 book(s) has been added.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 2
Enter the name of the user: Bob
Enter the initial number of borrowed books: 10
Borrower "Bob" borrowing 10 book(s) has been added.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Note that the readPosInt method prevents the initial number of books from being negative, so the constructor
for the Borrower class will never throw a NotALenderException when you create a borrower object.
Nevertheless the code of the main method of your CLI class must handle this exception by printing the error
message "BUG! This must never happen!" and immediately terminating the program using
System.exit(1);
Action 3: get the number of books borrowed by a given user.
When the user of the system specifies action 3, your program must ask the user to type the name of a user, and the
program then prints the number of books which is currently borrowed by this user.
For example (where 3, Anna, 3, and Bob are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -5 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 10 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
If the name of the user is wrong, then an UnknownUserException exception will be thrown by the Library
object. The code of the main method of your CLI class must catch this exception, print the error message from the
exception object, and then it just goes back to printing the menu of actions (by just going back to the beginning of
the while loop).
For example (where 3 and aaaa are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: aaaa
User aaaa unknown.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Action 4: increasing the number of books of a given user.
When the user of the software specifies action 4, your program must ask the user to type the name of a user, and a
number of books, and the program then uses that number to increase the number of books lent or borrowed by the
user. Then the program goes back to the main menu.
For example:
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -5 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: Anna
Enter the number of books: 2
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 10 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: Bob
Enter the number of books: 2
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 12 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
If the name of the user is wrong, then an UnknownUserException exception will be thrown by the Library
object. The code of the main method of your CLI class must catch this exception, print the error message from the
exception object, and then it just goes back to printing the menu of actions (by just going back to the beginning of
the while loop).
For example (where 4, aaaa, and 2 are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: aaaa
Enter the number of books: 2
User aaaa unknown.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Note that, even if a consumer is a borrower, the readPosInt method prevents the typed number of books from
being negative. This means a borrower will never throw a NotALenderException. Nevertheless the code of the
main method of your CLI class must handle this exception by printing the error message "BUG! This must
never happen!" and immediately terminating the program using System.exit(1).
For example (where 3, Bob, 4, Bob, and -15 are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 12 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: Bob
Enter the number of books: -15
Positive integers only!
Enter the number of books:
Action 5: decreasing the number of books of a given user.
When the user of the software specifies action 5, your program must ask the user to type the name of a user, and a
number of books, and the program then uses that number to decrease the number of books lent or borrowed by the
user. Then the program goes back to the main menu.
Note: the library object that you are using does not have a method to decrease books. So, in the code of the main
method of the CLI class, simulate decreasing books by simply increasing books by a negative number! For example,
decreasing the number of books of a user by 5 books is the same as increasing the number of books by -5 books.
For example:
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Anna
Enter the number of books: 6
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -1 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 12 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Bob
Enter the number of books: 5
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
If the name of the user is wrong, then an UnknownUserException exception will be thrown by the Library
object. The code of the main method of your CLI class must catch this exception, print the error message from the
exception object, and then it just goes back to printing the menu of actions (by just going back to the beginning of
the while loop).
For example (where 5, aaaa, and 2 are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: aaaa
Enter the number of books: 2
User aaaa unknown.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
If a consumer is a borrower and the number of books typed by the user is too big, then a
NotALenderException exception will be thrown by the Borrower object. The code of the main method of
your CLI class must catch this exception, print the error message from the exception object, and then it just goes
back to printing the menu of actions (by just going back to the beginning of the while loop).
For example (where 3, Bob, 5, Bob, 10are inputs from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Bob
Enter the number of books: 10
A borrower cannot lend 3 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6):
Action 6: quitting the program.
When the user of the system specifies action 6, your program must print a "Goodbye!" message, and terminate
the program using: System.exit(0).
For example (where 6 is an input from the user):
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 6
Goodbye!
Here is a more complete example of running the system:
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): aaaa
You must type an integer!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): -100
Positive integers only!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 7
Unknown action!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 1
Total number of borrowed books: 0
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 0
Unknown user role!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 3
Unknown user role!
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 1
Enter the name of the user: Anna
Enter the initial number of borrowed books: 5
Lender "Anna" lending 5 book(s) has been added.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 2
Type the user role (lender:1 borrower:2): 2
Enter the name of the user: Bob
Enter the initial number of borrowed books: 10
Borrower "Bob" borrowing 10 book(s) has been added.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 1
Total number of borrowed books: 5
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -5 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 10 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: aaaa
User aaaa unknown.
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: Anna
Enter the number of books: 2
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 10 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 4
Enter the name of the user: Bob
Enter the number of books: 2
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 12 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Anna
Enter the number of books: 6
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Anna
Anna borrows -1 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 12 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Bob
Enter the number of books: 5
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 5
Enter the name of the user: Bob
Enter the number of books: 10
A borrower cannot lend 3 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 3
Enter the name of the user: Bob
Bob borrows 7 book(s).
Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): 6
Goodbye!
Question 7
We now want to create a graphical user interface (GUI) for our library book lending system. Since we want the
system to have multiple views, we will use the Model-View-Controller design pattern.
First, create a ModelListener interface with the following UML specification:
+-------------------+
| <> |
| ModelListener |
+-------------------+
| + update(): void |
+-------------------+
This interface will be implemented by views and the model will use this interface to notify the views that they need
to update