Letterkenny Institute of Technology

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1 Letterkenny Institute of Technology Course Code: OOPR K6A02 BACHELOR OF SCIENCE IN COMPUTING WITH BUSINESS APPLICATIONS MULTIMEDIA AND DIGITAL ENTERTAINMENT COMPUTER SECURITY & DIGITAL FORENSICS COMPUTER GAMES DEVELOPMENT BACHELOR OF SCIENCE (Honours) IN APPLIED COMPUTING Subject: Introduction to OO Programming 2 Stage: 1 Date: Summer 2012 Examiners: Ms. M. Boyle Mr. J. Conaghan Mr. N. McKelvey Dr. S. Wright Ms. O. McMahon Time allowed: 2 hours INSTRUCTIONS Answer any three Questions Use code to illustrate your answers where necessary Introduction to OO Programming 2 Page 1 of 12

2 Question 1 (A) What is the output of the following Java code? int[] dailytemperatures = new int[] 12, 15, 9, 12, 8, 14, 13; System.out.println("Temperature"); System.out.println(dailyTemperatures[0]); System.out.println(dailyTemperatures[2]); (2 Marks) (B) Modify the code provided in part A so that it uses a for( ) loop to print out all the elements of the dailytemperatures array. (3 Marks) (C) Add another array called days to the code provided above. This array should contain the days of the week (Monday, Tuesday etc.). Rewrite the for() loop from part B so that it produces the following output: Day Temperature Monday 12 Tuesday 15 Wednesday 9 Thursday 12 Friday 8 Saturday 14 Sunday 13 (4 Marks) (D) Using these arrays, add a piece of code that asks the user to enter the name of a day. The program should then print out the temperature for that day. (You may wish to refer to the String methods in Appendix A). Sample output: Enter a day: Friday On Friday it was 8 degrees. (6 Marks) (E) Show how you would modify this code so that it ignores case differences in searching for the day. (You may wish to refer to the String methods in Appendix A). (2 Marks) Introduction to OO Programming 2 Page 2 of 12

3 (F) Add a piece of code that asks the user to enter a value. The program should then count and output the number of days in which the temperature exceeded that value. (4 Marks) (G) Add a piece of code that finds the hottest and coldest days in the week. (4 Marks) Introduction to OO Programming 2 Page 3 of 12

4 Question 2 (A) Given the Class and Tester programs below, what will be the output of HowToAccessStaticMethodTester? (4 Marks) //Class public class HowToAccessStaticMethod private int i; private static int j = 200; public static void staticmethod() System.out.println("you can access a static method this way:"); j=j+j; System.out.println(j); public void nonstaticmethod() i=100; j=1000; System.out.println((i*i)+(j/i)); System.out.println((j%10)); System.out.println(i); //Tester Program public class HowToAccessStaticMethodTester public static void main(string[] args) HowToAccessStaticMethod.staticMethod(); (B) Amend the Tester program HowToAccessStaticMethodTester so that it calls the method nonstaticmethod(). What is the new output? (7 Marks) Introduction to OO Programming 2 Page 4 of 12

5 (C) Given the Class and Tester program below, what will be the output of TheRectangleTester? (8 Marks) public class Rectangle int l, b; double p, q; public Rectangle(int x, int y) l = x; b = y; public int first() return(l * b); public Rectangle(int x) l = x; b = x; public int second() return(l * b); public Rectangle(double x) p = x; q = x; public double third() return(p * q); public Rectangle(double x, double y) p = x; q = y; public double fourth() return(p * q); THE TESTER PROGRAM APPEARS ON THE NEXT PAGE Introduction to OO Programming 2 Page 5 of 12

6 public class TheRectangleTester public static void main(string args[]) Rectangle rectangle1=new Rectangle(2,4); int areainfirstconstructor=rectangle1.first(); System.out.println(" The area of a rectangle in first constructor is : " + areainfirstconstructor); Rectangle rectangle2=new Rectangle(5); int areainsecondconstructor=rectangle2.second(); System.out.println(" The area of a rectangle in first constructor is : " + areainsecondconstructor); Rectangle rectangle3=new Rectangle(2.0); double areainthirdconstructor=rectangle3.third(); System.out.println(" The area of a rectangle in first constructor is : " + areainthirdconstructor); Rectangle rectangle4=new Rectangle(3.0,2.0); double areainfourthconstructor=rectangle4.fourth(); System.out.println(" The area of a rectangle in first constructor is : " + areainfourthconstructor); (D) Write a method calledcalculateperimeter() in the Rectangle class that will calculate and return the perimeter. Amend TheRectangleTester to call on this method and output the perimeter (length + width * 2) of rectangle4. (6 Marks) Introduction to OO Programming 2 Page 6 of 12

7 Question 3 (A) Implement a Date class as specified in the following UML class diagram. Date day: int month: int year: int Date(int, int, int) tostring(): String (3 Marks) (B) Provide the java code to declare a Date object called startofterm which represents the date 1/9/2012. (2 Marks) (C) Implement a Meeting class as specified in the following UML class diagram. Meeting officenumber: int meetingdate: Date Meeting (int, Date) tostring(): String (5 Marks) (D) Add a new instance variable meetingparticipants to the Meeting class. This variable should be an ArrayList of Strings, and will contain the names of the people who will attend the meeting. Extracts from the ArrayList class are provided in Appendix B. (2 Marks) Introduction to OO Programming 2 Page 7 of 12

8 (E) Add the following methods to the Meeting class: getnumberofparticipants() a method to return the number of names in the meetingparticipants instance variable (2 Marks) addparticipant() a method to add a new name to the meetingparticipants instance variable. (2 Marks) removeparticipant() a method which will accept a name, and will then remove that name from the meetingparticipants instance variable. (3 Marks) (F) Provide the Java code to declare a Meeting object called projectreview which will take place on 25/5/2012 in office number Provide a line of code to call each of the methods written in part E. (6 Marks) Introduction to OO Programming 2 Page 8 of 12

9 Question 4 (A) Java Strings are Immutable. Explain using diagrams, why the immutability of Java Strings is a disadvantage and suggest a way to avoid this disadvantage. (5 Marks) (B) Write a Java class called NameAddress which is modelled in the following UML class diagram. Your answer must include the method code. NameAddress Class Name title:string name:string address:string county:string Instance Variables NameAddress() gettitle():string settitle(string):void tostring():void equals(nameaddress):boolean Methods UML Representation of class NameAddress (5 Marks) (C) In your own words, explain how you would overload the NameAddress constructor so that it can be called either with no parameters, or with three String parameters. Your answer should show how both constructors would be invoked. (4 Marks) Introduction to OO Programming 2 Page 9 of 12

10 (D) Using the required String and/or StringBuilder methods from APPENDIX A, write the following methods for classnameaddress: (i) isfemale() returns true if the title is Miss, Ms, Mrs (regardless of case) and false otherwise. (3 Marks) (ii) appendcounty() adds the String Co. onto the start of the county instance variable. (5 Marks) (E) Give the Java code to do the following: (i) Create a NameAddress object called mydetails with initial values of Ms, Lisa Simpson, SpringField, NYC for the instance variables. You should use the overloaded constructor to create mydetails. (ii) Check and display if mydetails is female or not by calling the isfemale() method. (iii) DisplaymyDetails on the screen. (3 Marks) Introduction to OO Programming 2 Page 10 of 12

11 APPENDIX A String Methods boolean startswith(string prefix) Tests if this string starts with the specified prefix. boolean equals(object anobject) Compares this string to the specified object. boolean equalsignorecase(string anotherstring) Compares this String to anotherstring, ignoring case considerations. StringBuilder Methods StringBuilder insert(int offset, String str) Inserts the string into this character sequence. String tostring() Returns a string representing the data in this sequence. Introduction to OO Programming 2 Page 11 of 12

12 APPENDIX B ArrayList Methods boolean add(e e) Appends the specified element to the end of this list. void add(int index, E element) Inserts the specified element at the specified position in this list. boolean contains(object o) Returns true if this list contains the specified element. E E get(int index) Returns the element at the specified position in this list. remove(int index) Removes the element at the specified position in this list. boolean remove(object o) Removes the first occurrence of the specified element from this list, if it is present. E int set(int index, E element) Replaces the element at the specified position in this list with the specified element. size() Returns the number of elements in this list. Introduction to OO Programming 2 Page 12 of 12