Description
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.
Warm-up Question 1 (0 points)
Write a method that takes an input an array of integer arrays and checks if all of the numbers in each
‘sub-array’ are the same. For example, if the input is:
{{1, 1, 1}, {6, 6}}
then it should return true and if the input is:
{{1, 6, 1}, {6, 6}}
it should return false.
Warm-up Question 2 (0 points)
Write a method that takes as input an array of double arrays and returns the double array with the
largest average value. For example, if the input is:
{{1.5, 2.3, 5.7}, {12.5, −50.25}}
then it should return the array {1.5, 2.3, 5.7} (average value is 3.17).
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Warm-up Question 3 (0 points)
Write a class describing a Cat object. A cat has the following attributes: a name (String), a breed
(String), an age (int) and a mood (enum Mood). The cat constructor takes as input a String and sets
that value to be the breed. The mood of a cat can be one of the following: sleepy, hungry, angry,
happy, crazy. The Cat class also contains a method called talk(). This method takes no input and
returns nothing. Depending on the mood of the cat, it prints something different. If the cat’s mood is
sleepy, it prints meow. If the mood is hungry, it prints RAWR!. If the cat is angry, it prints hsssss.
If the cat is happy it prints purrrr. If the cat is crazy, it prints a random String of between 10 and 25
characters (letters).
The cat attributes are all private. Each one has a corresponding public method called getAttributeName()
(ie: getName(), getMood(), etc.) which returns the value of the attribute. All but the breed also
have a public method called setAttributeName() which takes as input a value of the type of the attribute and sets the attribute to that value. Be sure that only valid mood sets are permitted. (ie, a cat’s
mood can only be one of five things). There is no setBreed() method because the breed of a cat is set
at birth and cannot change.
Test your class in another file which contains only a main method. Test all methods to make sure they
work as expected.
Warm-up Question 4 (0 points)
Write a class Vector. A Vector should consist of three private properties of type double: x,y, and z.
You should add to your class a constructor which takes as input 3 doubles. These doubles should be
assigned to x,y, and z. You should then write methods getX(), getY(), getZ(), setX(), setY(), and
setZ() which allow you to get and set the values of the vector.
Warm-up Question 5 (0 points)
Add to your Vector class a method calculateMagnitude() which returns a double representing the
magnitude of the vector. The magnitude can be computed by taking
p
x
2 + y
2 + z
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Warm-up Question 6 (0 points)
Write a method scalarMultiply which takes as input a double[], and a double scale, and returns
void. The method should modify the input array by multiplying each value in the array by scale.
Question to consider: Would this approach work if we had a double as input instead of a double[]?
Warm-up Question 7 (0 points)
Write a method deleteElement which takes as input an int[] and an int target and deletes all
occurrences of target from the array. The method should return the new int[]. Question to consider:
Why is it that we have to return an array and can’t simply change the input parameter array?
Warm-up Question 8 (0 points)
Write the same method, except this time it should take as input a String[] and a String. What is
different about this than the previous method? (Hint: Remember that String is a reference type.
Assignment
The questions in this part of the assignment will be graded.
Part 2:
Question 1: Intro to Objects: Robot City (40 points)
For this question you have to get a robot (represented by a coloured triangle) to navigate a maze and
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(a) Initial Position (b) Ending Positions
Figure 1: Result of the getLoot() method
collect flashing lights. You are provided with an object-oriented model of the world using cities, robots
and flashing lights. Instead of creating your own classes you will be using software that has already
been developed by Byron Becker at the University of Waterloo. Before you begin, please review the
application programming interface (API) for the classes provided in the becker.robots package. That
is, you need to read the documentation in order to figure out which methods are available to you. To
complete the assignment, you will need the following files.
• a4-becker.jar This is an archive file which contains all of the additional Java classes that you will
need for the assignment.
• a4-becker-docs.zip This is an archive file which contains documentation about the classes included in the provided jar file.
All the above files can also be found at: http://www.learningwithrobots.com/software/downloads.
html Additional information on this package can be found at: http://www.learningwithrobots.com/
doc/becker/robots/package-summary.html. In order to get the provided file RobotsMoveLights.java
to compile, and to use the robot objects, you need to tell your computer where to find the a4-becker.jar
file.
• Eclipse Users: To do this in Eclipse, right click on your project folder (the first folder in the Package
Explorer pane on the left hand side of the screen). Go down to ‘Build Path’ and then click on ’Add
External Archives…’. You then have to find the location of the a4-becker.jar file, select it, and
click ‘open’. If you did not move the file, it should be in your ‘Downloads’ folder.
• Dr Java Users: Go into Edit and then click on Preferences. Then click on Resource Locations.
Under ‘Extra Classpath’ click on Add. You then have to find the location of the a4-becker.jar
file in your computer, select it and the click on ‘select’. If you did not move the file, it should be in
your ‘Downloads’ folder. You then click on Apply, and then Okay. You may have to quit DrJava
and reopen it for the changes to take effect.
Now that you have set up the a4-becker.jar file, you should be able to compile and execute RobotsMoveLights.java. When you execute the program, it should display an image similar to Figure 1(a). Note
that the mazes are randomly generated, so it is normal that the layout of your maze is different from
the one in the photo.
Your task is to give the robot (the coloured triangle) a series of commands such that at the end your
image will look like Figure 1(b). In Figure 1(b), it doesn’t matter if your robot is facing a different
direction, as long as it is in the correct location. You should not have to modify the main method in this
file – just the getLoot() method. This method takes as input a reference to a Robot object. Initially,
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there are three flashers placed throughout the maze. The robot has to navigate the maze, collect the
flashers, and bring them back to its original position. Once the robot has picked up the last flasher, it
must change colour before ‘going home’. In the example, it changes from red to green, although you
may choose any colour change that you like.
It is important to note that no matter what specific maze is generated, every square can always be
reached via a standard ‘follow the right wall’ method of exploration. It is therefore required that you
program the robot to find the flashers using this technique.
For details, see https://en.wikipedia.org/wiki/Maze_solving_algorithm#Wall_follower
Some methods that might be useful to you are: robot.move(), robot.turnLeft(), robot.pickThing(),
robot.getIntersection(). In order to get full marks, you will have to use others as well. This list
should just help get you started. Your method must work regardless of the exact location of flashers and
the formation of the maze. Note that it is recommended to write small ‘helper’ methods if you wish.
For example, there is no robot.turnRight() method. You may want to write your own method that
does this. This is completely optional.
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Question 2: Making your own Objects: Hangman (60 points)
For this question, you will create your own objects in order to implement the game of hangman. Hangman
is a guessing game for two players, or a player and a computer. One player (or a computer) thinks of
(generates) a word, phrase or sentence and the other tries to guess it by suggesting letters. The guessing
player has a limit on the maximum number of incorrect guesses she can make before losing the game.
She knows how many letters are in the word, and is told which letters are correct as she make guesses.
She also has access to the list of letters she has already guessed.
1. For the first part, you will create a Letter class. A letter in hangman has two private attributes:
(a) A char value, value, indicating the character value of the letter.
(b) A boolean value, isGuessed, indicating whether or not its value has been guessed by the
player.
The Letter constructor takes as input the character of the letter and sets value accordingly. It
also sets the default value of isGuessed to be false.
This class also has the following public methods:
• getValue() This method returns the value of the value attribute.
• getRevealed() This method returns the value of the isGuessed attribute.
• reveal() This method changes the value of isGuessed from false to true.
Be sure to test your Letter class thoroughly before moving on to the next part!
2. In the next part, you will create the Hangman class. This class has the following private attributes:
• An array of Letter values called letters.
• A char array called guesses. This array will store (at least) all of the incorrect, valid characters
guessed by the player.
• A boolean, gameOver, indicating whether or not the game is over.
• An int, maxNumGuesses, which stores the maximum number of incorrect guesses permitted.
• An int, numGuessesMade, which keeps track of the number of incorrect guesses made by the
player.
The Hangman class has the following public methods:
• A constructor that takes as input a String corresponding to the mystery word. It converts the
String to uppercase and then sets all of the values in the letters array to the characters of the
input String. This constructor also sets the maximum numbers of incorrect guesses to a default
value of eight.
• A constructor that takes as input a String corresponding to the mystery word, as well as the
maximum number of incorrect guesses. It then sets the letters and maxNumGuesses attributes
accordingly.
• A playGame method that takes no input, returns nothing, and plays a complete game of hangman
from start to finish.
Note: in the constructors, you may assume that the input String contains only valid characters. Additionally, be sure to initialize the guesses array to a reasonable size, as well as initialize all of the other
private attributes.
You will also need to write the following private methods:
• A method called guess that takes as input a character and returns a boolean value indicating
whether or not the guess was valid (invalid guesses include symbols, and incorrect characters that
have already been guessed). If it is valid and incorrect, this method will convert the character to
uppercase, and add the character to the guesses array. If it is valid and correct, it will update the
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boolean isGuessed attribute of any applicable Letter values in the letters array. If applicable, it
will also update the value of the numGuessesMade attribute.
• A method called displayBoard that prints the following information: The valid incorrect guesses
made thus far, the (partially revealed) word, and the number of remaining guesses.
You may write any additional helper methods that you deem appropriate. Ensure that any such methods
you write are private.
When the game finishes, you should either indicate to the player that they have won, or let them know
that they have lost. In both cases, you should print the full mystery word.
A sample run-through of the game is shown on the last page of this assignment. You are welcome to
change the phrasing of the dialogue, as long as you include all relevant information.
What To Submit
You have to submit one zip file with all your files in it to MyCourses under Assignment 3. If you do not
know how to zip files, please ask any search engine or friends. Google might be your best friend with this,
and a lot of different little problems as well.
RobotsMoveLights.java
Letter.java
Hangman.java
Optional: confessions.txt
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