School of Information Technology Atkinson Faculty of Liberal and Professional Studies York Universit

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School of Information Technology Atkinson Faculty of Liberal and Professional Studies York University AK/ITEC 1620 3.0M&N – Object-Based Programming Sample Exam

FINAL EXAMINATION DURATION: 3 hours

Name:_______________________________________________________

Student Number: _____________________________________________

INSTRUCTIONS 1. Closed book exam; no materials allowed 2. Print your name and student number on the cover page 3. Do not take exam sheets apart 4. Use back of sheets if you need more space 5. The duration of this exam is 180 minutes SCORE PART A: ____________ / 40 PART B: ____________ / 60 TOTAL: ____________ / 100

AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

APIs for Part A

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AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

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AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

PART A: FIND OUTPUT OF JAVA CODE FRAGMENTS [40 marks] 1. What is the output of the following Java code fragment? [5 marks] String s = "York University"; int i = 3; int j = 9; int p = s.indexOf("n"); int q = s.substring(++i, j++).indexOf("n"); System.out.println(p + " " + i); System.out.println(q + " " + j);

Answer:

6 4 2 10 2. What is the output of the following Java code fragment? [6 marks] String s = "abcdefgh"; int k = s.length() - 6; System.out.println(s.substring(k, s.length() - 1));

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AK/ITEC 1620 3.0A&B: Object-Based Programming

boolean b = s.substring(1,2) == "b"; System.out.println(b); Answer:

cdefg false

3. What is the output of the following Java code fragment? [4 marks] int i1, i2, i3; double r1, r2; i1 = 5; r1 = 3.0; r2 = 2 * ++r1; i2 = 2 * (i1 %= 8); i3 = i2 / (int)r2; System.out.println(r2); System.out.println(i3); Answer:

8.0 1 4. What is the output of the following Java code fragment? [5 marks] int x = 5763; int y = 0; int k; for(k = 0; x > 0; k++){ y = y + x % 10; x = ++x / 10; } System.out.println(k); System.out.println(y); Answer:

4 21

5. What is the output of the following Java code fragment? [5 marks] String s1 = "100"; String s2 = "20"; System.out.println(s1 + s2 + 30);

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Fall 2007

AK/ITEC 1620 3.0A&B: Object-Based Programming

System.out.println(9 / 2 + 30 + s1 + s2);

Fall 2007

Answer:

1002030 3410020

6. What is the output of the following Java code fragment? [3 marks] for(int i = 1; i <= 5; i++){ for(int j = 0; j < i; j++){ System.out.print(i); } System.out.println(); } Answer:

1 22 333 4444 55555 7. What is the output of the following Java code fragment? [6 marks] Investment max, min; Investment[] investmentArray = new Investment[5]; investmentArray[0] = new Investment(new Stock("SCOTIA"), 100, 100.0); investmentArray[1] = new Investment(new Stock("ROYAL"), 100, 300.0); investmentArray[2] = new Investment(new Stock("SCOTIA"), 10, 150.0); investmentArray[3] = new Investment(new Stock("TD"), 50, 250.0); investmentArray[4] = new Investment(new Stock("ROYAL"), 10, 275.0); max = min = investmentArray[0]; for(int i = 0; i < investmentArray.length; i++){ if(investmentArray[i].getBookValue() > max.getBookValue()){ max = investmentArray[i]; } if(investmentArray[i].getBookValue() < min.getBookValue()){ min = investmentArray[i]; } } System.out.println(max.getStock().getSymbol() + " @ $" + max.getBookValue()); System.out.println(min.getStock().getSymbol() + " @ $" + min.getBookValue());

Answer:

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AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

ROYAL @ $300.0 SCOTIA @ $100.0

8. What is the output of the following Java code fragment? [6 marks] DecimalFormat df = new DecimalFormat(“0.##”);

final double MARKET_INCREASE = 1.1; Portfolio p = new Portfolio("ITEC Investments", 3); p.add(new Investment(new Stock("IBM"), 10, 200.0)); p.add(new Investment(new Stock("DELL"), 20, 50.0)); p.add(new Investment(new Stock("HP"), 30, 100.0)); System.out.println("Original values: "); for(int i = 0; i < p.size(); i++){ System.out.println("Total " + p.get(i).getStock().getSymbol()+ “: “ + df.format(p.get(i).getQty() * p.get(i).getBookValue())); } System.out.println("New values: "); for(int i = 0; i < p.size(); i++){ p.get(i).setBookValue(p.get(i).getBookValue() * MARKET_INCREASE); System.out.println("Total " + p.get(i).getStock().getSymbol()+ “: “ + df.format(p.get(i).getQty() * p.get(i).getBookValue())); }

Answer:

Original values: Total IBM: 2000.00 Total DELL: 1000.00 Total HP: 3000.00 New values: Total IBM: 2200.00 Total DELL: 1100.00 Total HP: 3300.00

PART B: PROGRAMMING QUESTION [60 marks] 1) [15 marks]

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AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

Using the Coin class with the API shown below design and implement the driver class FlipRace which creates two Coin objects , then continually flips them both to see which coin comes up Heads three flips in a row. Continue flipping the coins until one coin wins the race and also consider the possibility that both coins achieve the objective in the same time (that will be a tie). Print the results of each turn and at the end print the winner and the total number of flips that were required.

Possible output: flip 1 Tails Tails flip 2 Tails Tails flip 3 Tails Tails flip 4 Tails Heads flip 5 Tails Heads flip 6 Heads Tails flip 7 Tails Heads flip 8 Heads Tails flip 9 Heads Heads flip 10 Tails Tails flip 11 Heads Heads flip 12 Heads Tails flip 13 Heads Tails First coin is the winner after 13 flips The API for Coin class is: public Coin() // default constructor public void flip() //Flips the coin by randomly choosing a face value. public boolean isHeads() //Returns true if the current face of the coin is heads public String toString() // Returns the current face of the coin as a string.

Answer public class FlipRace { public static void main(String[] args) { Coin fCoin = new Coin(); Coin sCoin = new Coin(); int fCounter=0, sCounter=0, nrFlips=0; do { fCoin.flip(); sCoin.flip(); nrFlips++; System.out.println("flip"+nrFlips+fCoin.toString()+sCoin.toString()); if (fCoin.isHeads()) fCounter++; 8

AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

else fCounter=0; if (sCoin.isHeads()) sCounter++; else sCounter=0; } while (fCounter<3 && sCounter<3);

if (fCounter==3 && sCounter !=3) System.out.println("First coin is the winner after"+nrFlips+" flips"); else if (sCounter==3 && fCounter !=3) System.out.println("Second coin is the winner after"+nrFlips+" flips"); else System.out.println("The race anded in a tie after "+nrFlips+" flips"); } } 2) [15 marks] Write a Java program that asks the user to enter 10 integers from the keyboard and store them in an array.

Then the program prints all the numbers to the screen in the reverse order they were entered, and at the end the maximum and minimum numbers.

Answer: import java.util.Scanner; public class ReverseOrder{ public static void main(String[] args) { int[] a = new int[10]; int number = 10; Scanner input = new Scanner(System.in); int temp, min, max; for(int i = 0; i < number; ++i){ System.out.print("Enter number: "); a[i] = input.nextInt(); } max = min = a[number-1]; for(int j = number-1; j >= 0; j--){ System.out.print(a[j] + " "); if(a[j] > max) max = a[j]; 9

AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

if(a[j] < min) min = a[j]; } System.out.println("Max number is: " + max); System.out.println("Min number is: " + min); } } 3) [15 Marks]

Consider the following (partial) API of two classes: class Department Department(String name, int budget) Parameters: name - name of the department budget - budget of this department void assign(Employee who) Parameter: who - the employee to be assigned to this department int getHeadCount() Returns: the number of employees in this department int getBudget() Returns: the budget of this department void changeBudget(int delta) Increase or decrease the budget of this department by the passed amount. Delta is the increment or decrement, not the new budget.

Parameter: delta - change the budget by adding this amount to it (to reduce budget, provide a negative amount). class Employee Employee(String name,int rank) Parameters: name - name of the employee rank - the rank (level) of the employee Develop the Java application App whose main method performs the following tasks, in the order shown: 1. Create a department called "R&D" with budget $2,000,000 and a department “Marketing” with a budget $1,000,000.

2. Create an employee John whose rank is 3, create an employee Debbie whose rank is 2.

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AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

4. Assign John to the R&D department and Debbie to “Marketing”.

5. Determine the head count of the R&D department and if it is greater than 10, increase the department budget by 10%, otherwise reduce it by 10%.

7. Check the R&D budget and if it is over $2,100,000 transfer $500,000 from R&D to Marketing.

Answer: public class App{ public static void main(String[] args){ Department d = new Department (“R&D”,2000000); Department m = new Department (“Marketing”,1000000); Employee e1 = new Employee (“John”, 3); Employee e2 = new Employee (“Debbie”, 2); d.assign(e1); m.assign(e2); int count = d.getHeadCount(); if (count>10) d.changeBudget(d.getBudget()*0.1); else d.changeBudget(-d.getBudget()*0.1); if (d.getBudget()>2100000){ d.changeBudget(-500000); m.changeBudget(500000);

} }

4) [15 marks] Write a program which hard-codes employee data into an array of objects. The API of the Employee class contains: • Employee (String name, int age, double salary); • String getName(); • double getSalary(); This program will then display in alphabetic order the names of the employees with salaries between $40,000 and $60,000.

Answer: public class Driver { public static void main(String [] args) { Employee emp[] = new Employee [100]; Employee hold; int count=0; emp[0]=new Employee("Smith",53,56000); emp[1]=new Employee("Jones",20,34000); 11

AK/ITEC 1620 3.0A&B: Object-Based Programming Fall 2007

emp[2]=new Employee("Adams",30,55000); emp[3]=new Employee("Simms",45,50000); emp[4]=new Employee("Travis",60,60000); for ( int pass = 1; pass < count; pass++ ) { // loop to control number of comparisons for ( int e = 0; e < count - 1; e++ ) { if ( emp[e].getName().compareTo (emp[e+1].getName())>0 ) { hold = emp[e]; emp[e] = emp[e+1]; emp[e+1] = hold; } } } for (int i=0; i<count ; i++){ if (emp[i].getSalary()>40000 && emp[i].getSalary()<60000 ) System.out.println(emp[i].getName()); } } }

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