Last Name: Circle One: OCW Non-OCW

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1 First Name: AITI 2004: Exam 1 June 30, 2004 Last Name: Circle One: OCW Non-OCW Read Instructions Carefully! This is a 3 hour closed book exam. No calculators are allowed. Please write clearly if we cannot understand your answer, you will receive 0 points for that question. This exam has 6 parts worth a total of 100 points. Section 1 Java Basics (20 points) 1. (2 points) ( T / F ) Java programs must be compiled separately for each platform. 2. (2 point) ( T / F ) In Java, the identifiers Bob and bob refer to the same variable. 3. (2 points) The command we use to compile Java code is a. java b. javac 4. (2 points) The command we use to run a Java program is a. java b. javac 5. (2 points) Which of the following are valid variable names? a. true6 b. you-me c. hello Java d. DEGREE 6. (3 points) Which of the following are valid statements? a. int i = 5 b. short s = 5; c. boolean firsttime; d. char c = '4'; 7. (2 points) What is the value of the following arithmetic expressions? a. (4 + 3) * 6 2 = 40 b. 14 % (18 / 5) = 2 8. (5 points) What is the value of the following Boolean expressions? boolean b1 = false; boolean b2 = true; a. b1 && b2 = false b. b1 b2 = true c. b2 b1 = true d.!b1 = true e. (!b1) && b2 = true Page 1 of 7 1

2 Section 2: Control Structures (15 points) 1. (2 points) What does the following code print to the screen? int score = 75; String orange = "apple"; String apple = "orange"; if (score >= 60) System.out.println(apple); else System.out.println(orange); a. apple b. orange 2. (2 points) What is the output of the following code? char grade = 'D'; switch (grade) { case 'A': System.out.println("Excellent"); break; case 'B': System.out.println("Good"); break; case 'C': System.out.println("OK"); break; default: System.out.println("Let's talk"); Let's Talk 3. (5 points) Write a for loop that calculates the sum of the first 100 multiples of 3, (3, 6, 9, ). (Note: This is not the same as the sum of the multiples of 3 from 1 to 100) int sum = 0; for(int i = 1; i <= 100; i++) { sum += 3 * i; 4. What is the output for the following segment of the code? a) int k = 10; while (k < 10) { k += 2; no output System.out.println(k); b) int k = 10; 12 while (k < 20) { 14 k += 2; 16 System.out.println(k); Page 2 of 7 2

3 Section 3: Methods and Arrays (10 points) 1. (5 points) Write a method, product, which takes an integer array as an argument and returns the product of the numbers in that array. (It multiplies the elements of the array). // static keyword is optional public static int product(int[] nums) { int p = 1; for(int i = 0; i < nums.length; i++) { p *= nums[i]; return p; 2. (5 points) The following piece of code calls a method called scaleproduct. The first argument to scaleproduct is an array of integers and the second is an integer. The method takes the product of the array and returns the sum of the product and the second argument. int[] numbers = {1,2,3,1; int scale = 3; int ans = scaleproduct(numbers, scale); //1*2*3*1 + 3 System.out.print(ans); Output: 9 Write the scaleproduct method. To take the product of the array, it should call the product method you wrote above. public static int scaleproduct(int[] nums, int scale) { return product(nums) + scale; Page 3 of 7 3

4 Section 4 Lists and Iterators (15 points) 1.(4 points) List one advantage and one disadvantage of using an ArrayList compared to an array. One advantage of using an ArrayList over an array is that it will automatically resize for you as necessary, and it will do so in an optimal fashion. One disadvantage of using an ArrayList is that it cannot store primitives, so you have to wrap your primitives in objects before adding them to the ArrayList, and then extract the primitive value from these objects when you access them from the ArrayList. 2. (4 points) Would an ArrayList or a LinkedList be more appropriate for the following applications? - To store the people waiting in line at a bank, where a lot of people are continually joining the line at the end and leaving from the front, but you never want to search or reorder the line. a) ArrayList b) LinkedList - To store the grade books of a fixed number of students in this class that you want to update. a) ArrayList b) LinkedList 3. (7 points) Using an Iterator, complete the method below that takes the product of all the integers in the given ArrayList. You can assume java.util.* is imported. (Hint: The Integer class has a method with signature: public int intvalue()) static int product(arraylist intlist) { int product = 1; Iterator intiter = intlist.iterator(); while(intiter.hasnext()) { int i = ((Integer)intIter.next()).intValue(); product *= i; return product; Page 4 of 7 4

5 Section 5 Packages Access and Scope (8 points) class TestScope { int x = 0; int y = 0; void f() { int y; //LINE A y = 20; x = 10; void print() { System.out.println(x); f(); System.out.println(x); System.out.println(y); 1. (4 points) What will this code print out? (4 points) What will this code print out if we remove LINE A? Section 5 Static and Final (12 points) 1. (4 points) Add two public constants of type double to the Thermometer class below, one for the freezing point and one for the boiling point in Celsius. The freezing point is 0 degrees Celsius and the boiling point is 100 degrees Celsius. 2. (4 points) Add a public static method to the thermometer class to convert degrees Celsius to degrees Fahrenheit. It should accept a double argument in Celsius and return a double in Fahrenheit. The conversion is Fahrenheit = 1.8 * Celsius package thermo; public class Thermometer { public static final double FREEZING_POINT = 0.0; public static final double BOILING_POINT = 100.0; public static double convert(double celsius) { return 1.8 * celsius + 32; Page 5 of 7 5

6 3. (4 points) In the main method of UseThermometer, use the Thermometer class to calculate and print the boiling point in degrees Fahrenheit. package thermo; public class UseThermometer { public static void main(string args[]) { double fahrenheit = Thermometer.convert(Thermometer.BOILING_POINT); System.out.println(fahrenheit); Section 6 Classes (20 points) 1. On the next page write a class to represent a football team in a package called football. We want to be able to access the class FootballTeam from any package. The team has the following properties, which cannot be accessed outside of the class. - name of the team - number of wins - number of losses Write a constructor that accepts the name of the team, the number of wins, and the number of losses as arguments and sets the class properties to those values. This constructor should be accessible from any package. Write a second constructor that takes only the name of the team as an argument. This constructor should set the name of the team to the argument and the set the number of wins and losses to 0. (Hint: The body of this constructor should be one line and it should call the first constructor.) This constructor should be accessible from any package. Write methods that return the name of the team, the number of the wins, and the number of losses. These methods should be accessible from any package. Next write a method to increase the numbers of wins by 1 and another method to increase the number of losses by one. These methods should only be accessible from inside the football package. Write a method that returns true when a team has a "good" record, meaning the team has more wins than losses. This method should be accessible from any package. Finally, add a main method to the FootballTeam class. In the main method, construct a FootballTeam named "AITI" with 3 wins and 5 losses. Call the method that returns true when the team has a good record and print out the result. Now make three calls to the method that increases the number of wins by 1. Lastly, call the "good record" method again and print out the result. Page 6 of 7 6

7 package football; public class FootballTeam { private String name; private int numwins, numlosses; public FootballTeam(String name, int numwins, int numlosses) { this.name = name; this.numwins = numwins; this.numlosses = numlosses; public FootballTeam(String name) { this(name, 0, 0); public String getname() { return name; public int getnumwins() { return numwins; public int getnumlosses() { return numlosses; void addwin() { numwins++; void addloss() { numlosses++; public boolean hasgoodrecord() { return numwins > numlosses; public static void main(string[] args) { FootballTeam aiti = new FootballTeam("AITI", 3, 5); System.out.println("Good record? " + aiti.hasgoodrecord()); aiti.addwin(); aiti.addwin(); aiti.addwin(); System.out.println("Good record? " + aiti.hasgoodrecord()); Page 7 of 7 7

First Name: AITI 2004: Make-up Exam 1 July 9, Last Name:

First Name: AITI 2004: Make-up Exam 1 July 9, 2004 Last Name: Read Instructions Carefully! This is a 2 hour closed book exam. No calculators are allowed. Please write clearly if we cannot understand your