ASSIGNMENT 4. COMP-202C, Summer Due: Monday June 29th, 2015 (23:30)

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1 ASSIGNMENT 4 COMP-202C, Summer 2015 Due: Monday June 29th, 2015 (23:30) Please read the entire pdf before starting. You must do this assignment individually and, unless otherwise specified, you must follow all the general instructions and regulations for assignments. Graders have the discretion to deduct up to 10% of the value of this assignment for deviations from the general instructions and regulations. These regulations are posted on the course website. Be sure to read them before starting. Part 1: Part 2, Question 1: Part 2, Question 2: Part 2, Question 3: 0 points 50 points 30 points 20 points 100 points total Before starting on the assignment, you should download from the course website the following files. Make sure to save them in the same working folder. For Question1 : Vector2D.java City.java Country.java MakeCountry.java CountryMap.java For Question2 : DoublyLinkedList.java Node.java For Question3 : names.txt This imgsupport.java file will both be used for loading, displaying, and saving the image files. This will be needed throughout the assignment. The.jpg files are used to test your implementations. 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 through automated tests. While these tests will not determine your entire grade, it will speed up the process significantly, which will allow 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 :) 1

2 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 class describing a Cat object. A cat has the following attributes: a name (String), a breed (String), an age (int) and a mood (String). 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. Your Cat object 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 2 (0 points) Write a program that opens a.txt, reads the contents of the file line by line, and prints the content of each line. To do this, you should use look up how to use the BufferedReader class 1. Remember to use the try and catch statements to handle errors like trying to open an non-existent file. Warm-up Question 3 (0 points) Modify the previous program so that it stores every line in an ArrayList of String objects. You have to properly declare an ArrayList to store the results, and use add to store every line that your program reads in the ArrayList. Warm-up Question 4 (0 points) Finally, modify your program so that, after reading all the content in the file, it prints how many words are inside the text file. To do this, you should use the split method of the String class. Assume the only character that separates words is whitespace " ". 1 The documentation of the BufferedReadder class is available at io/bufferedreader.html. You can find an example on how to use it at bufferedreader_readline.htm Page 2

3 Part 2 The questions in this part of the assignment will be graded. Question 1: Making your own Objects: Cities and Roads (50 points) In this problem, you will implement an abstraction of a Country. The Country class contains an array of City objects. A City is defined by a two dimensional (x, y) position 2, a name, and its neighboring cities. Once the country is populated with cities, your code will determine whether or not the all the cities in the country are connected 3.Using your random country, you will be able to create a map of it using the provided CountryMap.java. Figure 1 depicts completed countries. (a) A non connected sample country (b) A connected sample country Figure 1: Examples of connected and non-connected countries You have been given all the files you need to solve this problem. The files provided for this question are: 1. Vector2D.java 2. City.java 3. Country.java 4. MakeCountry.java 5. CountryMap.java Go through all the comments in the provided files for this question. The comments explain in detail what needs to be done in each of the given files. The part where you are expected to implement a piece of code will be indicated with a comment TODO. In order to create your random country, you will have to populate the provided files with class variables and methods. An overview is shown in Figure 2. The following expands further on the content of each class and their functionalities. 1. Vector2D.java: This file describes an abstraction of a two dimensional vector, a Vector2D object. This class has two private attributes of type double, e.g. an x position and a y position. These values are set by the constructor. This file also contains a distance method that takes as input another Vector2D object and returns the distance between the argument vector and this vector reference, recall d = (v x w x ) 2 + (v y w y ) 2, where v and w are vectors and d is the euclidean distance that separates them. 2. City.java: This class is an abstraction of a city. The file you have been given contains the attributes, as well as some empty methods. You have to complete the file as follows: 2 Vector2D class 3 From any city is it possible to reach any other city by traveling along roads Page 3

4 Methods Class: Country boolean setconnectivity() City[] getcities()) String getname() Class: City void setneighbours( double maxdist,city[] cities) void explore() Vector2D getpos() String getname() String getexplored City[] getneighbours() Class: Vector2D double distance(vector2d v) double getx() double gety() Attributes String name boolean isconnected City [] cities String[] nameprefixes String[] namesuffixes Vector2D pos City[] neighbours boolean explored int numneighbours double xval double yval Figure 2: An overview of the Country, City and Vector2D classes The constructor: The City constructor takes no input and initializes the City class by giving it a random name and a position. In order to create the random name, take an element from a random index of the nameprefixes array and an element from a random index of the namesuffixes array. Concatenating the two together will give the String representing the city s name. Random integer can be generated by using the java.util.random library. To generate a Random integer between 0 and 100, you can do, Random randomgenerator = new Random(); randomgenerator.nextint(100); For more details about Random library, look up at api/java/util/random.html You are encouraged to add more prefixes and suffixes to the arrays (if you wish). The constructor should also initialize the city s position, a Vector2D object, by choosing two random integers between 0 and 150 and setting those values to be the x and y vector coordinates respectively using the Vector2D s constructor. The City[] neighbours attribute: Each city has an array of neighbouring cities. Two cities are deemed to be neighbours if the distance between them is less than some threshold. For the image in Figure 1, a maximum distance of 50 was used. You can play with this value. The maximum number of neighbours is, of course, the number of cities in the country minus one 4. The setneighbours(double maxdist, City[] cities) method populates the neighbours attribute. It takes as input an array of all cities in the country and determines which to add as a neighbour of the current city. A neighbour is defined as any City whose distance to the current City is less than maxdist. In order to determine the size of the array, infer from the following: there are n City instances in a Country object, and a city cannot be its own neighbour. This method does not return anything. Also at the end of setting the Neighbours, make sure to set numneighbours to the exact number of neighbours this city has (Not including the spots that have null in the neighbours array). 4 A city cannot be its own neighbour Page 4

5 The explore() method performs a breadth-first exploration of the Country. For more information, see The pseudo-code is as follows: function explore( ) explored true for all City v in neighbours do if v was not explored then v.explore() end if end for end function This algorithm starts at any City, and then explores all of the city s neighbours. We explore a City by setting its class variable, explored, to be true. If any of the neighbours are not already explored, then we explore their neighbours, and so on. When this algorithm terminates, the explored parameter will be true for every City for which there exists a path between itself and the starting City. 3. The Country.java file. This file defines a class Country. A country has the following private attributes: a name, an array of City objects, and a boolean variable (isconnected) that notes whether or not the country is connected. You will also need: A constructor: This takes as input the name of the country an integer n, representing the number of Cities that should exist in the Country, as well as an integer maxdist representing the maximum distance two neighbouring Cities can be from each other. The constructor sets the name and then initializes the n City objects, and sets neighbours for each city in the cities array. A method called setconnectivity(). This method should first call the explore method from the first City in the Country (cities[0].explore()). It should then iterate through all cities in the Country and verify the values of their boolean explored attributes to determine whether or not every city can be reached from every other city. It should return true if the cities are connected and false otherwise. Also implement the getter methods for cities and the name of the country (getcities( ) and getname( )). 4. The MakeCountry.java file. Here is where your main method is. This method creates a Country, determines whether or not its graph is connected and then creates the diagram of the Country. You should also have a print statement that states whether or not the Country is connected. Question 2: Implementing a Doubly LinkedList (30 points) For this question, you will implement a doubly linked list 5. To do this we provide you the DoublyLinkedList.java and the Node.java files. First, modify the Node class so that it contains a reference to both the previous and next elements in the list. Then, you should complete the DoublyLinkedList class by implementing the following methods: 1. find: This method receives a String value as input, and returns the first Node that matches the value. It returns null otherwise. 2. insertstart: This method receives a String value, and insert a Node with the given value at the beginning of the list. 3. insertend: This method receives a String value, and inserts a Node with the given value at the end of the list. 4. remove: This method receives a String value, and removes all occurrences of the value in the list. 5 Page 5

6 5. removeatindex: This method receives an int index, and removes from the list the element at the position given by the index. 6. tostringreverse: This method returns a string containing all the elements in the list in reverse order. To test if your code works, use the main method in the DoublyLinkedList.java file. Question 3: Sort the Names (20 points) In this question, you are required to read a list of names from the input file provided (names.txt) into an ArrayList String. Then you need to implement a method called Sort that takes this ArrayList as an input and sorts the names in the increasing alphabetical order. For example, if the input list of names is: { ada, aaa, adc, acd }, the sorted list will have { aaa, acd, ada, adc }. Once the ArrayList is sorted, you will write the names in the sorted ArrayList into another text file named sortednames.txt. The detailed instructions for this question are as follows, You are given a text names.txt, that contains a list of Strings, one per line. Write a class called Question3 (in Question3.java). In the main method of this class, you will read the Strings from the file names.txt into an ArrayList. Then call the Sort method (that you will be implementing) with the ArrayList of names as a parameter. You are required to implement a Sort method that takes ArrayList as input parameter and sorts the elements in this ArrayList. For Sorting, you can use the Bubble Sort algorithm, that we saw in the class. In this case, you will be comparing two strings. Use comparetoignorecase( ) method defined under the Strings to compare two Strings. Look up at lang.string) for more details on this method. Once the ArrayList is sorted, in the main method : write the names into another text file with name sortednames.txt. You can use the BufferedReader and BufferedWriter classes for File input / output operations as taught in the class. What To Submit You should submit your assignment on MyCourses. In order to do this, you will need to make a zip of the file. You can do this on windows by following the instructions at this link: slytinen/instructions/zip.html. On a mac or linux, you can find instructions at com/2012/01/10/how-to-zip-files-in-mac-os-x/ You should submit a zip file called Assignment4.zip with the following files inside of it. Vector2D.java City.java Country.java MakeCountry.java Node.java DoublyLinkedList.java Question3.java sortednames.txt Confession.txt (optional) In this file, you can tell the TA about any issues you ran into doing this assignment. If you point out an error that you know occurs in your problem, it may lead the TA to give you more partial credit. On the other hand, it also may lead the TA to notice something that otherwise he or she would not. Page 6