SCHOOL OF COMPUTING, ENGINEERING AND MATHEMATICS SEMESTER 2 EXAMINATIONS 2014/2015 CI101/CI101H. Programming

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1 s SCHOOL OF COMPUTING, ENGINEERING AND MATHEMATICS SEMESTER 2 EXAMINATIONS 2014/2015 CI101/CI101H Programming Time allowed: THREE hours Answer: ALL questions Items permitted: Items supplied: There is no restriction on the paper-based items or items on a USB flash drive that the student may take into the examination. None CI101_SEM2_2014/2015 Page 1 of 22 Printing date: 23/09/2015

2 Section A Section A carries 50 marks in total. Use the application provided to record the answer for each multiple choice question (Question 1 Question 20) in section A of this exam paper. Remember to fill in your student number in the box provided for this (Highlighted initially with a reddish background) before exiting from the application. Each question in Section A is worth 2.5 marks. Section A carries 50 marks in total. There is no penalty for answering a question wrongly. Question 1 class Main public static void main( String args[] ) String message = " %s"; System.out.printf( "Message %s" + message, "for today", "warm" ); When executed the above Java application will print: (a) Message %s %s for today warm (b) Message for today (c) Message for today warm (d) for today warm CI101_SEM2_2014/2015 Page 2 of 22 Printing date: 23/09/2015

3 Question 2 class Main public static void main( String args[] ) int value = 5; value = 7 / 2; System.out.println( value ); value = 7 / 3; System.out.println( value ); value = 7 % 2; System.out.println( value ); value = 7 % 7; System.out.println( value ); When executed the above Java application will: (a) The number 2 twice. (b) The number 1 twice. (c) The number 0 twice. (d) 4 different numbers in descending order. CI101_SEM2_2014/2015 Page 3 of 22 Printing date: 23/09/2015

4 Question 3 class Main public static void main( String args[] ) int large = 100; int small = 1; if ( large >= small ) System.out.println("OK"); if ( large <= large ) System.out.println("OK"); if ( small >= large ) System.out.println("OK"); if ( small <= large ) System.out.println("OK"); if ( small <= large && small >= large ) System.out.println("OK"); When executed the above Java application will: (a) (b) (c) (d) Print OK 4 times. Print OK 3 times. Print OK 2 times. Print OK once. CI101_SEM2_2014/2015 Page 4 of 22 Printing date: 23/09/2015

5 Question 4 class Main public static void main ( String args[] ) int rooms[] = new int[5]; // Line A System.out.println( rooms[0] ); int rooms[] = new int[1]; System.out.println( rooms[0] ); int rooms[] = 0,1,2 ; System.out.println( rooms[0] ); int rooms[]; System.out.println( rooms[0] ); // Line B // Line C // Line D The above Java application will fail to compile because: (a) There are multiple declarations of rooms, lines A, B, C and D. (b) Line C is not valid Java. (c) Line D is not valid Java. (d) The compiler will detect that the declaration of rooms in Line D may not have been initialised. CI101_SEM2_2014/2015 Page 5 of 22 Printing date: 23/09/2015

6 Question 5 interface Animal public String speak(); public String name(); public int age(); class Dog implements Animal private String name = ""; private int age = 0; public Dog( String nameis, int ageis ) name = nameis; age = ageis; public String speak() return "bark"; public String name() return this.name; public int age() return this.age; For the above fragment of a Java application, which of the following statements would be true? (a) Animal pet = new Dog(); Would be a valid declaration at an appropriate point in a later part of the Java application. (b) Animal pet = new Dog( "Cleo", 4 ); Would be a valid declaration at an appropriate point in a later part of the Java application. (c) Animal pet = new Animal( "Cleo", 4 ); Would be a valid declaration at an appropriate point in a later part of the Java application. (d) All of the above declarations (a), (b) or (c) would be an invalid declaration at an appropriate point in a later part of the Java application. CI101_SEM2_2014/2015 Page 6 of 22 Printing date: 23/09/2015

7 Question 6 class Main static int value = 10; public static void main( String args[] ) int value = 0; for ( int i=1; i<=2; i++ ) value += i; System.out.println( value ); After executing the above Java application the result printed would be: (a) 1 (b) 2 (c) 3 (d) 10 Question 7 Which of the following declarations is NOT valid inside a Java class? (a) public int start(int n) return n>1? start(n-1) : 1; (b) private final int question = 7; (c) public int answer = 7; (d) boolean this = true && false; CI101_SEM2_2014/2015 Page 7 of 22 Printing date: 23/09/2015

8 Question 8 When combined with other Java code the following statement: System.out.printf( "[%s] is [%d] characters long\n", "Brighton", "Brighton".length() ); when executed will print: (a) (b) (c) (d) [Brighton] is [8] characters long [Brighton ] is [8] characters long [ Brighton] is [8] characters long A Java run time error message Question 9 class Main public static void main( String args[] ) int numbers[] = new int[4]; numbers[0] = 0; numbers[1] = 1; for ( int i=2; i< numbers.length; i++ ) numbers[i] = numbers[i-1] + numbers[i-2]; int sum = 0; for ( int val: numbers ) sum += val; System.out.println( sum ); When executed the above Java application will print: (a) 1 (b) 2 (c) 4 (d) 8 CI101_SEM2_2014/2015 Page 8 of 22 Printing date: 23/09/2015

9 Question 10 class Main public static void main (String args[] ) char name[] = 'H', 'A', 'L' ; for ( char c: name ) char nc = (char) ( ((int) c) + 1 ); System.out.print( nc ); System.out.println(); When executed the above Java application will print: (a) (b) (c) (d) HAL G K IBM A Java run time error message CI101_SEM2_2014/2015 Page 9 of 22 Printing date: 23/09/2015

10 A Diagram D1 B C Question 11 Diagram D1 represents the class structure of part of a Java application. Which of the following statements about that Java application is true? (a) If an instance of A is declared it will contain 1 instance of B. (b) If an instance of A is declared then when it is no longer accessible all references to the instances of C that are within an instance of B whose instance is within A will become inaccessible. (c) If an instance of A is declared then it will contain 50 instances of C. (d) The relationship between the class B and the class C is aggregation (has-a). Question 12 Diagram D1 represents the class structure of part of a program. In an implementation of class A (assume appropriate import statements have been made) which of the following declarations for state would help in the representation of all of the state of class A. (a) B state = new B(); (b) B state[] = new B[5]; (c) HashMap<A,C> state = new HashMap<>(); (d) TreeMap<A, ArrayList<C>> state = new TreeMap<>(); CI101_SEM2_2014/2015 Page 10 of 22 Printing date: 23/09/2015

11 Question 13 Which of the following statements about the Java language is true? (a) (b) (c) (d) An instance of an ArrayList may be extended by inserting a new element at the end. An instance of an ArrayList has an index that goes from 1 to the number of elements in the ArrayList. There is no way at run time of finding the number of elements in an instance of an ArrayList after new elements have been added. An instance of an ArrayList<Integer> may be used to store an instance of the primitive type double. Question 14 Which of the following statements about the Java language is true? (a) The Java collection class HashMap internally stores its keys in ascending order. (b) String pw = "North Meols".charAt(1); Will put "o" into the variable pw. (c) System.out.println( "hello".tolowercase() ); Will print hello (d) final double pi = 3.14; In subsequent code the value of pi may be changed to a better (more accurate) representation of pi. Question 15 Which of the following statements about the use of the architectural pattern MVC is true? (a) (b) (c) (d) There can only be 1 instance of the View The Model contains code to directly produce a visual representation of the View on an appropriate device. The behaviour of the model is implemented in the View. The view requests information from the model so that it can generate an appropriate representation of the Model. CI101_SEM2_2014/2015 Page 11 of 22 Printing date: 23/09/2015

12 Question 16 Which of the following statements about testing is true? (a) (b) (c) (d) In white box testing the tester does not see the code that they are testing. In black box testing the tester sees the code that they are testing. Using a JUnit test guarantees to discover all errors in the code of a class. In general you will not be able to exhaustively test if all possible inputs to a program will be processed correctly. Question 17 Which of the following statements about the Java language is true? (a) (b) (c) (d) The garbage collector is an attempt by Oracle to improve the detection of errors in a program using AI (Artificial Intelligence) techniques. All classes must have at least one explicit constructor. An import statement can occur anywhere within a Java program as long as the keyword import starts in columns The class construct may itself contain another class. Question 18 Which of the following statements is true? (a) (b) (c) (d) When a Java application with at least one executable statement is successfully compiled there will be at least one file created with extension.class. The debugger in BlueJ will help you find syntax errors in your program. The debugger in BlueJ will help you find semantic errors such as the use of a variable that has not been declared in your program. Any program written in Java today will still be compliable by the original Java compiler released to the world in 1995 hence the phrase "Write once run anywhere". CI101_SEM2_2014/2015 Page 12 of 22 Printing date: 23/09/2015

13 Question 19 Which of the following statements about the Java language is false? (a) (b) (c) (d) It is unwise in a program to hold a large monetary amount in a double if absolute accuracy is required. A boolean is an example of a primitive type. A class is an example of a reference type. In Java only primitive types may be held in an instance of an ArrayList. Question 20 In relationship to the standard conventions used for writing a Java application which of the following is true? (a) (b) (c) (d) As the screen size on many mobile devices is small developers should write their Java code starting at column 1 and then have a maximum of 40 characters on a line to maximise the readability of their code on mobile devices. The convention is that a class name starts with a lower case letter and then may have a mixture of upper and lower case letters. The convention is that a mutable (can be changed at run-time) variable name starts with a lower case letter. The convention is that developers should use very short names for variables and if at all possible a single letter to help speed up the compilation process. CI101_SEM2_2014/2015 Page 13 of 22 Printing date: 23/09/2015

14 Marks Section B Section B carries 50 marks Brief A Java application has been written to process data electronically collected by a meter reader. The application reads the processed collected data looking for anomalies in the readings gathered. The processed data consists of the customer's reference number, the current meter reading and then the previous meter reading. A customer's reference number of 0 terminates the data. The anomalies that can be identified in the data are as follows: Anomaly.Description / what is to be printed 1 No units used The message: "No usage" is printed. 2 The current reading is less than the previous reading The message: "Usage: current [val] is less than previous [val]" Is printed with val replaced by the appropriate meter reading. 3 A very high usage (> units is found) The message "Very high usage [val]" Is printed with val replaced by the usage Unfortunately the application contains in total 5 (Five) syntax, semantic or logical errors. Correct these errors in the program. Remember, it is to correct the errors not rewrite the Java application. PTO CI101_SEM2_2014/2015 Page 14 of 22 Printing date: 23/09/2015

15 Example input data Commentary Example Input Expected output Reading 1 Reading 2 Reading 3 Customer Investigate Usage: current [4] less than previous [8] No usage Very high usage [11000] // Customer ID // Current // Previous // End of data Special instructions Remember any line printed that contains a # will not be considered as part of your answer. This is so that you can write out a meaningful prompt for any data (containing a # character) and this line of text will be ignored in the comparison of your answer. The Java application A printed copy of the Java application for question 2.1(that contains the 5 (Five) errors mentioned above) is on the following page. PTO CI101_SEM2_2014/2015 Page 15 of 22 Printing date: 23/09/2015

16 //Please enter your student number here: // ^^^^^^^^ class Main public static void main( String args[] ) System.out.println("Customer Investigate" ); System.out.print( "#Enter ref. number: " ); int customer = BIO.getInt(); while ( customer > 0 ) System.out.print( "#Current use " ); int current = BIO.getInt(); System.out.print( "#Previuous use " ); int previous = BIO.getInt(); used = current - previous; if ( used > ) report( customer, "Very high usage [%d]", used, 0 ); if ( used <= 0 ) report( customer, "Usage: current [%d] less than previous [%d]", previous, current ); if ( used = 0 ) report( customer, "No usage", 0, 0 ); System.out.print( "#Enter Customer id " ); customer = BIO.getInt(); public static void report( int customer, String what, int val1, int val2 ) System.out.printf( "%8d ", customer ); System.out.printf( what, val1, val2 ); System.out.print(); There are 3 marks for each 'issue' successfully corrected. CI101_SEM2_2014/2015 Page 16 of 22 Printing date: 23/09/2015

17 Marks Brief Construct a Java program that will read in a single integer value representing the side of a square that is to be printed. When the square is printed the outline of the square is represented by * s and the interior is filled with alternate blank columns and columns filled with * s. For example, if 7 were input then the square would be 7 columns wide by 7 rows deep as shown below: ******* * * * * * * * * * * * * * * * * * * * * ******* Counting from 1 for the above square of size 7, the vertical bars (includes the left hand and right hand sides) would be at columns 1, 3, 5 and 7. However, if the size of the square read in is not appropriate then the error message "Not possible" is to be printed instead of printing the square. An inappropriate size for a square is less than 5 or an even number. Hint A positive number is even if - the remainder when divided by 2 is 0. A positive number is odd if - the remainder when divided by 2 is 1. PTO CI101_SEM2_2014/2015 Page 17 of 22 Printing date: 23/09/2015

18 Example input data Commentary Example Input 7 Size of square Expected output ******* * * * * * * * * * * * * * * * * * * * * ******* Example Input Expected output 4 Size of square Not possible Example Input 9 Size of square Expected output ********* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ********* CI101_SEM2_2014/2015 Page 18 of 22 Printing date: 23/09/2015

19 Marks Program solution (17 marks for a working program) Elegance/ appropriateness of solution (Max 3 marks) Brief Before the 15 th February 1971, the UK used a monetary system that was comprised of pounds, shilling and pence. A pound was made up of 20 shillings and 1 shilling was made up of 12 pence. Rather confusingly the symbol for pence was then d. Hence in the old monetary system there were 240d in a pound. This old monetary system was often referred to as sd or occasionally as L.s.d (LSD) which stood for the Latin currency denominations of librae, solidi, and denarii. Implement the class LSD that is used to hold instance of money in 'pounds, shillings and pence'. The class LSD implements the interface LSD_Protocol. The interface LSD_Protocol is defined on the following page which contains "java doc" comments about what each method does. Complete the methods in the class that you create in the following order: set asstring add sub mult divide The checking process used on your code, will first test the method set, then asstring, then add etc. Do make sure that the class LSD that you 'submit' compiles and you complete the methods in the order shown above. PTO CI101_SEM2_2014/2015 Page 19 of 22 Printing date: 23/09/2015

20 interface LSD_Protocol /** * Set the amount to (in old money) * returns false if shillings < 0 or > 20 * pence < 0 or > 12 pounds Number of pounds shillings Number of shillings pence Number of pence true if valid amount false otherwise */ public boolean set(int pounds, int shillings, int pence); /** * Return as a String a representation of the * amount held in Pounds Shilling and Pence * 2 3shillings 6pence => "P2 3s 6d" * 0 0shillings 6pence => "P0 0s 6d" String representing the amount in old money */ public String asstring(); /** * Add to the amount (in old money): pounds Number of pounds; shillings Number of shillings pence Number of pence */ public void add( int pounds, int shillings, int pence ); /** * Subtract from the amount (in old money): pounds Number of pounds; shillings Number of shillings pence Number of pence */ public void sub( int pounds, int shillings, int pence ); /** * Multiply the amount held by: by Number to multiply by */ public void mult( int by ); /** * Divide the amount held by * [The answer is the equivalent of (value in pence)/by] by Number to divide by */ public void divide( int by ); PTO CI101_SEM2_2014/2015 Page 20 of 22 Printing date: 23/09/2015

21 The following program (In class Main) can be used as a quick test for the class LSD. class Main public static void main( String args[] ) LSD m = new LSD(); System.out.printf( "Answer construct = %s\n", m.asstring() ); boolean check = m.set( 0, 0, 13 ); //Invalid amount if (! check ) System.out.printf( "13 pence Invalid amount\n" ); check = m.set( 0, 21, 0 ); //Invalid amount if (! check ) System.out.printf( "21 shillings Invalid amount\n" ); check = m.set( -7, 19, 11 ); //Valid if (! check ) System.out.printf( "But is valid\n" ); m.set( 10, 4, 0 ); //10 Pounds, 4 Shillings, 0 Pence System.out.printf( "Answer set = %s\n", m.asstring() ); m.set( 0, 0, 0 ); for ( int pounds = 0; pounds < 2; pounds++ ) for ( int shillings=0; shillings < 20; shillings++ ) for ( int pence = 0; pence < 12; pence++ ) m.add( pounds, shillings, pence ); System.out.printf( "Answer add = %s\n", m.asstring() ); m.set( 500, 0, 0 ); for ( int pounds = 0; pounds < 2; pounds++ ) for ( int shillings=0; shillings < 20; shillings++ ) for ( int pence = 0; pence < 12; pence ++ ) m.sub( pounds, shillings, pence ); System.out.printf( "Answer sub = %s\n", m.asstring() ); m.set( 3, 7, 10 ); m.mult( 3 ); System.out.printf( "Answer mult = %s\n", m.asstring() ); m.set( 10, 3, 6 ); m.mult(3); m.divide( 3 ); System.out.printf( "Answer divide = %s\n", m.asstring() ); PTO CI101_SEM2_2014/2015 Page 21 of 22 Printing date: 23/09/2015

22 The result from executing this 'test' program for the class LSD should be: Answer construct = P0 0s 0d 13 pence Invalid amount 21 shillings Invalid amount Answer set = P10 4s 0d Answer add = P479 0s 0d Answer sub = P21 0s 0d Answer mult = P10 3s 6d Answer divide = P10 3s 6d Special instructions Hints A BlueJ project for question 2.3 is provided. In this BlueJ project is the class Main, which contains the test program shown above. The interface LSD_Protocol and finally an incomplete implementation (No state or behaviour) of the class LSD that will not compile. Your task is to complete the class LSD so that the class Main when executed as a program will produce the correct output. When you create the class LSD use the body of the interface to create the methods in the class. Replacing the ';' with an appropriate body for each method. If you do not complete a method make sure that the method will compile so that the class Main can be used to test the other methods that you have implemented. CI101_SEM2_2014/2015 Page 22 of 22 Printing date: 23/09/2015