ASSIGNMENT 2 COMP-202

ASSIGNMENT 2
COMP-202
Please read the entire PDF before starting. You must do this assignment individually.
It is very important that you follow the directions as closely as possible. The directions, while
perhaps tedious, are designed to make it as easy as possible for the TAs to mark the assignments by letting
them run your assignment, in some cases through automated tests. While these tests will never be used to
determine your entire grade, they speed up the process significantly, which allows the TAs to provide better
feedback and not waste time on administrative details. Plus, if the TA is in a good mood while he or she is
grading, then that increases the chance of them giving out partial marks. :)
Up to 30% can be removed for bad indentation of your code as well as omitting comments, or poor coding
structure.
To get full marks, you must:
• Follow all directions below
– In particular, make sure that all classes and method names are spelled and capitalized exactly
as described in this document. Otherwise, you will receive a 50% penalty.
• Make sure that your code compiles
– Non-compiling code will receive a 0.
• Write your name and student ID as a comment in all .java files you hand in
• Indent your code properly
• Name your variables appropriately
– The purpose of each variable should be obvious from the name
• Comment your work
– A comment every line is not needed, but there should be enough comments to fully understand
your program
1
Part 1 (0 points): Warm-up
Do NOT submit this part, as it will not be graded. However, doing these exercises might help you to do the
second part of the assignment, which will be graded. If you have difficulties with the questions of Part 1, then
we suggest that you consult the TAs during their office hours; they can help you and work with you through
the warm-up questions. You are responsible for knowing all of the material in these questions.
Warm-up Question 1 (0 points)
Write a method swap which takes as input two int values x and y. Your method should do 3 things:
1. Print the value of x and y
2. Swap the values of the variables x and y, so that whatever was in x is now in y and whatever was
in y is now in x
3. Print the value of x and y again.
For example, if your method is called as follows: swap(3,4) the effect of calling your method should be
the following printing
inside swap: x is:3 y is:4
inside swap: x is:4 y is:3
Warm-up Question 2 (0 points)
Consider the program you have just written. Create two integer variables in the main method. Call
them x and y. Assign values to them and call the swap method you wrote in the previous part using x
and y as input parameters.
After calling the swap() method—inside the main method— print the values of x and y. Are they
different than before? Why or why not?
Warm-up Question 3 (0 points)
Write a method that takes three integers x, y, and z as input. This method returns true if z is equal to
3 or if z is equal to the sum of x and y, and false otherwise.
Warm-up Question 4 (0 points)
Let’s write a method incrementally:
1. Start by writing a method called getRandomNumber that takes no inputs, and returns a random
double between 0 (included) and 10 (excluded).
2. Now, modify it so that it returns a random int between 0 and 10 (still excluded).
3. Finally, let the method take two integers min and max as inputs, and return a random integer
greater than or equal to min and less than max.
Warm-up Question 5 (0 points)
Create a file called Counting.java, and in this file, declare a class called Counting. This program takes
as input from the user (using args) a positive integer and counts up until that number. eg:
run Counting 10
I am counting until 10: 1 2 3 4 5 6 7 8 9 10
Warm-up Question 6 (0 points)
For this question you have to generalize the last question. The user will give you the number they want
the computer to count up to and the step size by which it will do so.
run Counting 25 3
I am counting to 25 with a step size of 3:
1 4 7 10 13 16 19 22 25
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Warm-up Question 7 (0 points)
Write a method getFirstHalf() that takes as input a String and returns a String composed of the first
half of the characters from the specified String. For example, getFirstHalf("cucumber") returns the
String "cucu", while getFirstHalf("apple") returns the String "ap" (thus, if the number of characters
is odd, you should round down).
Warm-up Question 8 (0 points)
Write a method alphaString() which takes two Strings as input and returns the String between the two
that comes first in the alphabet. For example, alphaString("banana", "apple") returns the String
"apple", while alphaString("snake", "squirrel") returns the String "snake".
Warm-up Question 9 (0 points)
Write a method replaceAll() which takes as input a String and two characters. The method returns
the String composed by the same characters of the given String where all occurrences of the first given
character are replaces by the second given character. For example, replaceAll("squirrel", ’r’ ,
’s’) returns the String "squissel", while replaceAll("squirrel", ’t’, ’a’) returns the String
"squirrel".
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Part 2
The questions in this part of the assignment will be graded.
Throughout this assignment you are allowed to use everything we have learned in class up to and including
loops (while and for). This does not mean however that you are allowed to change any of the headers of
the methods described below. You need to make sure to follow precisely the instructions provided.
For this assignment, you are NOT allowed to use the following:
• Any other method from the String class beside length(), charAt(), equals(), equalsIgnoreCase(),
toLowerCase(), and toUpperCase().In particular, you are NOT allowed to use substring(), split(),
contains(), indexOf(), or lastIndexOf().
• Any other class beside Math. In particular, this means that no import statements are allowed.
Question 1: Bunco (40 points)
Bunco is a dice game composed by six rounds. To play, all that is required is three dice. Normally Bunco
is played with 12 or more players divided into groups of four, but, for the purpose of this assignment,
we’ll be looking at a simplified version of Bunco played between 2 players. The players will take turns
rolling three dice trying to score points. At the end of the 6 rounds, the player with the highest number
of points wins then game.
The goal of this question is to write several methods in order to create a program that simulates two players playing a game of Bunco. All the code for this question must be placed in a file named Bunco.java.
A round of Bunco. As explained above, Bunco is a game of rounds. For the purpose of this question
we will assume that each of the two players is allowed to roll the three dice only once per round. Points
are awarded as such:
• 21 points if all three dice match the current round number (this is a “Bunco”).
• 5 points if all three dice match each other, but not the current round number (this is a “mini
Bunco”)
• 1 point for each die matching the current round number.
Each game consists of six rounds, progressing in order from one to six. The player with the highest
points at the end of the game wins.
Now that we know how the game works, let’s look at the methods we need in order to simulate two
players playing the game of Bunco.
1a. A method to simulate a dice roll
In a game of Bunco, each player rolls three six-sided dice. Write a method called diceRoll() that
simulates the roll of one six-sided dice. Such method takes no inputs, and it returns an integer between
1 and 6 (both included). Your method must use Math.random() in order to achieve the desired result. If
you have any doubts on how to write the method, make sure you first understand the warm-up Question
4, where you are asked to build a method called getRandomNumbers().
1b. A method to compute the score of a player
Write a method getScore() that computes the score of a player after he/she takes his/her turn rolling
the dice. This method takes as input three integer values that corresponds to the numbers the player
has rolled, as well as a fourth integers indicating the current round number. It then returns an integer
indicating the score achieved. Remember that, the points for each round of Bunco are awarded as
described in the paragraph above titled “A round of Bunco”.
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1c. A method to simulate one round of Bunco
Write a method playOneRound() that simulates one player playing one round of Bunco. This method
takes as input a String with the name of the player rolling the dice, and an integer indicating the current
round that has been played. The method returns an integer representing the score obtained by such
player. The method must use diceRoll() to simulate all the dice rolls necessary, and getScore() to
retrieve the points obtained. The method also prints the result of the dice roll as well as the score
obtained by the player. For example, if the method is called with inputs "Jikun" and 2, then it should
print something similar to the following:
Jikun rolled 2 5 2 and scored 2 points
In this case, the method also returns the value 2. On the other hand, if the method is called with input
"Lita" and 2, then it should print something similar to the following:
Lita rolled 1 6 4 and scored 0 points
In this case, the method returns the value 0. Note that, if the input indicating the round number is not
an integer between 1 and 6 (both included), then the method should display an error message indicating
that the input was not valid and return the value -1.
1d. A method to simulate a game of Bunco
Finally, write a method playBunco() that simulates a game of Bunco between two players. This method
takes two Strings as input indicating the names of the players. The method does not return any value.
The method simulates the two players playing rounds of Bunco. While doing so, it keeps track of the
total score of each player and at the end of each round it displays it on the screen. (Hint: think about
how to use a couple of extra variables to do so. Where should these variables be declared? Where and
how should they be updated?) The method simulates 6 rounds of Bunco and then determines the winner
of the game. A message indicating the winner should then be displayed. If there is a tie, the method
should print out a statement declaring that there was a tie.
To get full marks the method must use playOneRound(). Moreover, there should not be repetitions in
your code (for instance, you cannot repeat your code 6 times in order to simulate 6 rounds).
1g. Setting up the main method (Optional - No extra marks)
Set up the main method so that the program receives two inputs of type String via command line
arguments indicating the names of the players. From the main method, call playBunco() with the
appropriate inputs in order to simulate the two players playing Bunco. In the next pages you can find
a couple of examples of how your program should run. (Note that due to the randomness of the dice
rolls, the output will change each time you run your program)
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Question 2: Email Validation (60 points)
For this question, you will write a Java program that helps validate email addresses. Email addresses are
often requested as input to websites as a way to validate the identity of the user. To assure that the email
provided is actually good, a combination of various validation techniques is required. For the purpose of
this question, we will focus on checking whether or not a given string represents a syntactically correct
email address.
A valid email address consists of a prefix, an ‘@’ symbol, and an email domain. Both the prefix and
the domain must be written in acceptable formats. For instance, in the address john.smith@mail.com,
“john.smith” is the prefix, and “mail.com” is the domain.
Note that, we say that a character is alphanumeric if it is a letter of the alphabet, ‘A’ to ‘Z’ or ‘a’ to ‘z’,
or one of the arabic numerals, ‘0’ to ‘9’. For instance, ‘G’ is an alphanumeric character while ‘&’ is not.
Acceptable prefix formats. For a prefix to be acceptable it must adhere to the following constraints:
• It contains at least one character.
• It contains only alphanumeric characters, underscores (‘ ’), periods (‘.’), and dashes (‘-’).
• An underscore, a period, or a dash must always be followed by one or more alphanumeric characters.
• The first character must be alphanumeric.
Examples of valid prefixes are: “abc-d”, “abc.def”, “abc”, “abc def”.
Examples of invalid prefixes are: “abc-”, “abc..d”, “.abc”, “abc#def”.
Acceptable domain formats. For a domain to be acceptable it must adhere to the following constraints:
• It is made up of two portions separated by a period.
• The first portion contains at least one character.
• The second portion contains at least two characters.
• The first portion contains only alphanumeric characters, periods, and dashes. More over, a period
or a dash must always be followed by one or more alphanumeric characters.
• The second portion contains only letters of the alphabet.
Examples of valid domains are: “mail.cc”, “mail-archive.com”, “mail.org”, “mail.mcgill.ca” (here the
first portion of the domain is “mail.mcgill”, while “ca” is the second portion)
Examples of invalid domains are: “mail.c”, “mail#archive.com”, “mail”, “mail..com”, “.com”, “mail.c9”.
To complete your task, you need to implement all the methods listed below. All the code for this question
must be placed in the file named EmailValidation.java. Note that you are free to write additional
methods if they help the design or readability of your code.
2a) Method to check if a character is alphanumeric
Write a method isAlphanumeric() that takes as input a character. The method returns true if such
character is a letter of the English alphabet (uppercase or lower case) or one of the arabic numerals.
The method returns false otherwise. For example:
• isAlphanumeric(‘g’) returns true
• isAlphanumeric(‘B’) returns true
• isAlphanumeric(‘3’) returns true
• isAlphanumeric(‘-’) returns false
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2b) Methods to check is a character is a valid prefix/domain character
Write the following two methods:
• A method isValidPrefixChar() that takes as input a character and returns true if the character can be used in the prefix of a valid email address, false otherwise. Note that a valid
prefix can contain only alphanumeric characters, dashes, periods, or underscores. For example,
isValidPrefixChar(‘ ’) returns true, while isValidPrefixChar(‘&’) returns false.
• A method isValidDomainChar() that takes as input a character and returns true if the character
can be used in the domain (first portion) of a valid email address, false otherwise. Note that a
valid first portion of a domain can contain only alphanumeric characters, dashes, or periods. For
example, isValidDomainChar(‘-’) returns true, while isValidDomainChar(‘ ’) returns false.
To get full marks, your method must use the isAlphanumeric() method defined above.
2c) Method to check if a String contains exactly one ‘@’
Write a method exactlyOneAt() that takes as input a String representing a possible email address,
and returns true if the string contains exactly one ‘@’, false otherwise.
For example:
• exactlyOneAt("example@email.com") returns true.
• exactlyOneAt("b@n@n@s") returns false
• exactlyOneAt("@pple") returns true
2d) Method to get the prefix of a possible email address
Write a method getPrefix() that takes as input a String representing a possible email address. The
method returns a String containing the prefix of the possible email address. In this method, you can
assume that the String received as input contains exactly one ‘@’.
For example:
• getPrefix("example@email.com") returns "example".
• getPrefix("cats @nd dogs") returns "cats ".
• getPrefix("@pple") returns "".
2e) Method to get the domain of a possible email address
Write a method getDomain() that takes as input a String representing a possible email address. The
method returns a String containing the domain of the possible email address. In this method, you can
assume that the String received as input contains exactly one ‘@’.
For example:
• getDomain("example@email.com") returns "email.com".
• getDomain("cats @nd dogs") returns "nd dogs".
• getDomain("@pple") returns "pple".
2f) Methods to check if the prefix and the domain are valid
Write the following two methods:
• isValidPrefix() takes a String as input representing the prefix of a possible email address. The
method returns true if the input adhere to all the constraints listed in the above paragraph titled
“Acceptable prefix formats”, false otherwise.
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• isValidDomain() takes a String as input representing the domain of a possible email address.
The method returns true if the input adhere to all the constraints listed in the above paragraph
titled “Acceptable domain formats”, false otherwise.
Examples:
• isValidPrefix("abc def") returns true.
• isValidPrefix("mail.cc") returns true.
• isValidPrefix("abc..d") returns false.
• isValidPrefix("abc#d") returns false.
• isValidDomain("mail.cc") returns true.
• isValidDomain("abc-def.ghi") returns true.
• isValidDomain("abc..d") returns false.
• isValidDomain(".com") returns false.
To get full marks, your method must use at least isValidPrefixChar() and isValidDomainChar().
2g) Methods to check if a string is a valid email address
Write the method isValidEmail() which takes as input a String and returns true if the string is a
valid email address, false otherwise. To get full marks, your method must use all the methods you have
written up to now (either directly or indirectly).
For example:
• isValidEmail("abc..def@mail.com") returns false.
• isValidEmail("abc#def@mail.com") returns false.
• isValidEmail("abc.def@mail") returns false.
• isValidEmail("abc.def@mail..com") returns false.
• isValidEmail("abc d@mail.com") returns true.
• isValidEmail("abc.def@mail.com") returns true.
• isValidEmail("abc@mail.com") returns true.
• isValidEmail("abc.def@mail-archive.com") returns true.
What To Submit
Please put all your files in a folder called Assignment2. Zip the folder (DO NOT RAR it) and submit it
through MyCourses.
Inside your zipped folder, there must be only the following files. Do not submit any other files, especially
.class files. Any deviation from these requirements may lead to lost marks.
Bunco.java
EmailValidation.java
Confession.txt (optional) In this file, you can tell the TA about any issues you ran into doing
this assignment.
Note that the Assignment2 folder must not contain any subfolder!
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