CMPS 200 Homework Assignment 13, Fall 2012

Faculty of Arts & Sciences Department of Computer Science CMPS 200—Introduction to Programming Assignment 13 – Due Friday Jan 4, 2013 Reading Material Chapter 6. The chapter covers the built-­‐in Java I/O datatypes including the File, Scanner, and PrintStream datatypes. In this assignment, all I/O must be done with the standard Java I/O APIs i.e. File, Scanner and PrintStream. You may not use the In/Out classes we used in previous assignments. Exercises 1. Courses. The goal of this simple exercise is to illustrate how to handle data types whose instance variables are of object type. The Course data type below whose variables include TextBook and Instructor. Write the classes and answer the question below with an appropriate diagram. public class TextBook private String title, author, publisher; // instance variables public TextBook(String titl, String auth, String pub) // basic constructor public TextBook(TextBook t) // copy constructor public void set(String title, String author, String publisher) // mutator method public String toString() // string representation of textbook public class Instructor private String lastname, firstname, office; public Instructor(String lname, String fname, String office) // basic constructor public Instructor(Instructor inst) // copy constructor public void set(String lname, String fname, String office) public String toString() // string representation of textbook public class Course private String title; private Instructor instr; private TextBook text; public Course(String name, Instructor ins, TextBook txt) // basic constructor public String getName() // accessor method public Instructor getInstructor() // accessor method public TextBook getTextBook() // accessor method public String toString() // string representation of course public class CourseTest { public static void main(String[] args) { // Create Instructor objects Instructor instructor1 = new Instructor("Turkiyyah", "George", "Bliss 116"); Instructor instructor2 = new Instructor("Jaber", "Mohamad", "Bliss 309"); // Create TextBook objects TextBook text1 = new TextBook("Building Java Programs", "Stepp", "Pearson"); // Create Course objects Course course1 = new Course("CMPS 200", instructor1, text1); Course course2 = new Course("CMPS 200", instructor2, text1); // Display the courses information. System.out.println(course1); System.out.println(course2); } Question: Explain what problems might occur if the constructor of the Course class does not call the copy constructors for its instructor and textbook instance variables. Draw appropriate diagrams. Introduction to Computer Programming (CMPS 200) Fall 2012 2 of 4 2. Rotating Sentences. You are asked to rotate a series of input sentences 90 degrees clockwise, i.e., instead of displaying them from left to right and top to bottom, your program will display them from top to bottom and right to left. Write RotatingSequence program that takes the names of the input and output files as command line arguments. The file can contain a maximum of 100 sentences. Legal characters include: newline, space, any punctuation characters, digits, and lower case or upper case English letters. (NOTE: Tabs are not legal characters.) The output file should have the last sentence printed out vertically in the leftmost column; the first sentence of the input would subsequently end up in the rightmost column. Hint. Write a data type JaggedArrayChar that implements the methods whose signatures are shown below. public class JaggedArrayChar { private int nbLines; // number of lines private int maxLineLen; // maximum line’s length private char[][] jaggedArray = new char[100][]; // constructor, takes a file name and fill its content in the jaggedArray. // Also, this constructor stores the number lines in nbLines and the maximum line’s length in maxLineLen. public JaggedArray(String filename) {...} public char get(int i, int j) {...} // returns jaggedArray[i][j] public int getLineLength(int i) {...} // returns jaggedArrray[i].length public int getNbLines() {...} // returns nbLines public int getMaxLineLen() {...} // returns maxLineLen } Sample Input: Rene Decartes once said, "Cogito ergo Sum", which means, "I think therefore I am." Sample Output: ""R ICe on tge hi itD noe k c ea trr hgt eoe r s eS fuo omn r"c e,e Iws ha aii mcd .h, " m e a n s , Introduction to Computer Programming (CMPS 200) Fall 2012 3 of 4 3. Dice In this problem, you are going to perform some experiments that result from rolling two six-­‐sided dice. You will start by creating two classes Die and DicePair that will be used to answer follow-­‐up questions. Die and DicePair are given as follows: public class Die { public Die() // basic constructor public Die(int face, int n) // Constructs a die where a given face is “loaded, i.e., // is n times more likely to occur than the others public int roll() // returns a random integer between 1 and 6 } To implement a die where all six faces are equally likely to occur (fair die), the interval 0.0 -­‐ 1.0 could be divided into six segments of equal size. A random number between 0.0 and 1.0 can then be generated and and the segment it falls in is the roll of the die. If one of the faces is loaded, then the segment sizes have to be adjusted accordingly. For example if a 2 is three times more likely to occur than the other faces, the size of the segment corresponding to 2 has to be three times larger than the others. See figure below. public class DicePair { private Die[] dies; // instance variables public DicePair() {..} // constructor public DicePair(...) {..} // constructor for a loaded pair of dice public int roll() {..} // returns the sum of the values returned from rolling each Die } 3.1 DiceRun Write a program DiceRun.java to roll a pair of dice a certain number of times and store the results in a file. The program accepts two parameters from the command line: an integer N and a file name f. It will start by writing the integer N to the file. It will then call the roll() method of the DicePair class N times and store each roll value in the file on a separate line. Note that you will get different results at every run. C:> java DiceRun 5 dice-­‐pair-­‐runs.txt After running the command above dice-­‐pair-­‐runs.txt contains something like: 5 7 3 3 10 9 3.2 CountOccurrences Write a program CountOccurrences.java that accepts 2 arguments from the command line: the first is an integer (call it key) between 2 and 12 inclusive and the second is an integer N denoting the number of rolls to perform. Your program should roll the dice pair N times and output the number of occurrences of key in the rolls. C:> java CountOccurrences 3 6000 3 was rolled 306 times out of 6000 C:> java CountOccurrences 12 10000 12 was rolled 276 times out of 10000 Introduction to Computer Programming (CMPS 200) Fall 2012 4 of 4 3.3 FairDie Write a driver class called FairDie that checks the values of n rolls of a single Die and then decides whether the die is fair or not. The program takes an integer N that represents the number of times the die is rolled. If the Die is fair, the program should display on the console “Fair Die”. Otherwise, it will display “Unfair Die”. A Die is considered fair if all six outcomes (1 through 6) are equally likely to occur. The chi-­‐square test is usually used to check whether the die is fair or not. The following formula calculates chi-­‐square: 𝑋! = 1 6𝑛! (6𝐶! − 𝑛)! ! !!! where Χ2 is the chi-­‐square statistic (find it on Wikipedia), Ci is the number of occurrences of i, i.e. the number of occurrences of 1 is C1, the number of occurrences of 2 is C2, the number of occurrences of 3 is C3, etc., and n is the number of times the die was rolled. A Die is considered fair if the value of Χ2 is less than 0.02. Otherwise, it is not fair. You program should display if the die is fair or not and the value of Chi-­‐ Square. C:> java FairDie 10000 Chi-­‐Square = 1.2656E-­‐4 Fair Die