Final Examination Semester 3 / Year 2010

Transcription

1 Southern College Kolej Selatan 南方学院 Final Examination Semester 3 / Year 2010 COURSE : OBJECT-ORIENTED PROGRAMMING COURSE CODE : PROG 2013 TIME : 2 1/2 HOURS DEPARTMENT : COMPUTER SCIENCE LECTURER : LIM PEI GEOK Student s ID : Batch No. : Notes to candidates: 1) The question paper consists of 7 pages Section A: 10 questions (20 marks) Section B: 2 questions (20 marks) Section C: 2 questions (60 marks) 2) Answer all questions. 3) Write your answer for Section A and Section B in answer booklet. 4) Save your answer for questions in Section C and submit your answers in softcopy to Southern College E-Learning System.

2 SECTION A: MULTIPLE CHOICE QUESTION ( 10 X 2 = 20 MARKS ) Please choose most appropriate answer. State the answer in the answer booklet. 1. Assume Person class is superclass of Student class. Which of the following methods or data fields in Person class does not inherited to Student class? a. public static void display() b. protected String name c. Person() d. public String getname() 2. Which of the following operator is used to construct an object of a particular class type? a. The new operator b. The dot (.) operator c. The instanceof operator d. The + operator 3. Which of the following statement is FALSE about the override methods? a. You can override an instance method, but you can not override a data field. b. You can not override a static method, but if you declare a static method in a subclass with the same name as one in the superclass, then the one in superclass is hidden. c. You can not override a private method. d. You can declare a method in a subclass has the same name and parameter lists as a method in its superclass with a different return type 4. Which of the following is the key concept of object-oriented? i) Messages ii) Encapsulation and information hiding iii) Inheritance and Polymorphism iv) Modular a. i and iii b. i, ii and iii c. ii, iii and iv d. i, ii, iii and iv 5. The method tostring() is a public member of the class. a. Object b. Writer c. String d. Output 6. A subclass inherits from its superclasses a. private data b. protected data c. public data d. b and c 1/7

3 7. Methods that are not interface methods and that do not provide implementations must be declared using keyword. a. implements b. abstract c. extends d. interface 8. The ability for objects of different classes related by inheritance or interface implementation to response differently to the same method call. What is the ability mentioned here? a. interface b. polymorphism c. inheritance d. abstract 9. Which of the following class definitions defines a legal abstract class? a. abstract class Fruit{ b. abstract void displayinfo(); } c. abstract class Fruit{ d. abstract void displayinfo(){} } class Fruit{ abstract void displayinfo(); } class Fruit{ abstract void displayinfo(){} } 10. Which of the following statements is TRUE? a. An abstract class can have instances created using the constructor of the abstract class. b. An interface can have static methods. c. An interface can extend one or more interfaces. d. An interface can extend an abstract class 2/7

4 SECTION B: SHORT QUESTIONS ( 20 MARKS ) Answer all the questions in answer booklet. Question 1 (10 marks) Identify the error/s and rewrite the statement with correct codes. 1. There is one error in the following codes. (4 marks) 1 import java.util.*; 2 public class Test{ 3 public static void main(string[] args){ 4 ArrayList list = new ArrayList(); 5 list.add( Singapore ); 6 list.add(123); 7 list.add( Malaysia ); 8 String temp = list.get(2); 9 System.out.println(temp); 10 } 11 } 2. There are two errors in the following codes. (6 marks) 1 public class Box extends Rectangle{ 2 public String tostring(){ 3 return super.super.tostring() + Box class ; 4 } 5 } 6 7 class Rectangle extends GeometricObject{ 8 private double length; 9 private double width; 10 void setlength(double length){ 11 length = length; 12 } 13 } class GeometricObject{ 16 public String tostring(){ 17 return GeometricObject class ; 18 } 19 } 3/7

5 Question 2 (10 marks) a) What are the similarities and differences between abstract classes and interfaces? State out one similarity and one difference between abstract and interface class. (5 marks) b) Explain the similarities and differences between method overloading and method overriding. State out one similarity and one difference between method overloading and method overriding. Does it possible to have overloading method in same class? (5 marks) 4/7

6 SECTION C: CODING QUESTIONS (60 MARKS) Submit your answer in softcopy and upload it to Southern E-Learning System. Question 1 (35 marks) Best Education College is a new college which located in Johor Bahru. The manager of the college has hired you to develop a subject registration system for their college. In Best Education College, there are two types of study mode for their students which are full time and part time study mode. Both of the types of student have different term of their total number of credit hours allowed to register for each semester. You need to complete the following task in order to develop a subject registration system for Best Education College. Complete the following tasks: a) Create an abstract class named Student that includes data fields that hold the student id (for example, D ), course id (for example, IT ), and current credit hours for this semester (for example, 12). All of the data fields are required as arguments to the constructor method except for the current credit hours. Write the accessor and mutator methods for all the attributes in Student class. Write one abstract methods with String return type which named as addsubject(int credithour) where credithour is the argument that indicate the credit hours of the enrolled subject and is will be provided by user. Write a tostring() method to display the information of student id, course id and current credit hour. (14 marks) b) Create a subclass named FullTimeStudent. Declare two constant named MAX_CREDIT_HOUR and MIN_CREDIT_HOUR with values 18 and 12 to denote the maximum and minimum credit hours in one semester. Write constructor with two arguments to specify the student id and course id. Override the addsubject(int) method to calculate the current credit hour based on credit hour that supplied by the user. (12 marks) c) Create a subclass named PartTimeCustomer which override the method addsubject(int). Write constructor with two arguments to specify the student id and course id. Declare a constant named MAX_CREDIT_HOUR with values 9 to denote the maximum credit hours in one semester. (9 marks) The addsubject(int) method in both FullTimeStudent and PartTimeStudent classes should return a message based on the table 1 below. In addition, addsubject(int) method will update the current credit hour based on the conditions stated in table 1. Thus, it will return a meaningfully message to indicate the status of subject adding process. Sample output for this subject enrollment system is show as below. 5/7

7 Table 1: Message return by the addsubject(int) method based on credit hour provided by the user, the maximum and minimum credit hour for both full time and part time students. Condition Message Credit Hour FullTimeStudent PartTimeStudent > maximum credit hour If credit hours provided by the user exceed the maximum credit hour, then your system should display You are not allowed to enroll for the subject due to your credit hours for this semester is full. maximum credit hour and minimum credit hour Your system should add the credit hour into the current credit hour attribute stated in Student class and return a message Success added!. Your system should add the credit hour into the current credit hour attribute stated in Student class and return a message Success added!. < minimum credit hour Your system should return a message You have to enroll for a minimum of 12 credit hours every semester to be in status. Sample output: Student ID: D Course Id: IT Current Credit: 14 Success added! Student ID: D Course Id: IT Current Credit: 17 You are not allowed to enroll for the subject due to your credit hours for this semester is full. Student ID: D Course Id: IT Current Credit: 15 6/7

8 Question 2 (25 Marks) Design a class named as Stock that that implements the Comparable interfaces. Stock class contains: a) A string data field named name for the stock s name. b) A double data field named previousclosingprice that stores the stock price for the previous day. c) A double data field named currentprice that stores the stock price for the current time. d) A constructor that creates a stock with specific name. e) The accessor methods for all data fields. f) The mutator methods for previousclosingprice and currentprice. g) A method named changepercent() that returns the percentage changed from previousclosingprice to currentprice. The formula for the change percent is as follow: change percentage = (currentprice - previousclosingprice) previousclosingprice x 100 h) A method named as tostring() that return a string description for the stock. The descriptions should include the name, previousclosingprice, currentprice and the change percentage. The objects of Stock class should compare based on their change percentage /7