1. BAHRIA UNIVERSITY (Karachi Campus)
2. Department of Computer Science
3. Mid Term Examination – Spring 2020
4. OBJECT-ORIENTED PROGRAMMING (CSC-210)
5. (TAKE HOME ASSIGNMENT)
6. Class : BSCS 2nd Semester (A/B) (Morning)
7. Course Instructor(s) : Sameena Javaid Submission Deadline: 31st May 2020
8. Marks : 20
9. Student’s Name: ________________________________ Reg. # : ______________
10.  
11. QUESTION NO. 1 (Inheritance - Case Study) (10 Marks)
12. Maintain an employee management system for a company. The following UML diagram shows the
13. relationship between the classes.
14. Employee
15. - Name:String
16. - Id :int
17. - Qualifiction:String
18. + Employee( )
19. + setName( String n): void
20. + getName( ): String
21. + setId( int i): void
22. + getId( ): Int
23. + setQualification(String q): void
24. + getQualification( ): String
25. + DisplayInfo( ) : void
26. + getData( ):void
27. MonthlySalEmployee
28. - Basicpay : double
29. - Allowances : double
30. + getData ( ): void
31. + setBasicpay( double bp): void
32. + getBasicpay( ):double
33. + setAllowances( double al): void
34. + getAllowances( ): double
35. + DisplayInfo( ) : void
36. + SearchSalEmp( String name) : Boolean
37. Company
38. - arr1[ ] : MonthlySalEmployee
39. + addMonEmp(a : MonthlySalEmployee) : void
40. + displayEmpList( ) :void
41. Page 2 of 4
42. a) Write in java the MonthlySalEmployee class having following attributes and behaviors:
43. i. Basicpay: represents the basic pay of monthly salaried employee
44. ii. Allowances : represents the allowances of monthly salaried employee.
45. iii. getBasicpay() returns the employee basic pay & setBasicpay() change the employee
46. basic pay
47. iv. getAllowance( ) returns the employee allowance & setAllowance( ) changes the
48. employee allowance
49. v. getdata() takes information of employee as input
50. vi. displayinfo() displays all information related to employee
51. b) Write a Java class Company that contains the following attribute and methods:
52. i. arr1[ ]: an array of objects of MonthlySalEmployee type
53. ii. addMonEmp(a:MonthlaySalEmployee) adds objects of class MonthlySalEmployee in an
54. array of objects (Max 5 employees can be added)
55. QUESTION NO. 2 (reasoning questions) (05x1=05 Mark)
56. Answer the following questions (maximum of 2 sentences)
57. 1. Access specifiers determine whether a field or method in a class, can be used or invoked by
58. another method in another class or sub-class. Consider that java also take non-access specifiers
59. to restrict access. If the developer is willing to define class attributes and methods such that
60. these are shared by all the objects of the class? Help the developer to identify the type and
61. name of specifier.
62. 2. Predict output of the following and explain the working also.
63. public class University{
64. public static void main(String[] args) {
65.  int[] list = new int[]{1, 3, 5, 7, 9, 11, 15, 17, 19, 21};
66.  System.out.println(list[8%3]);
67. } }
68. Page 3 of 4
69. 3. Is following code correct? Yes/No? Explain the answer in either cases.
70. 4. Do you think the below code compiles successfully even though it is calling super class’s
71. protected constructor outside the package?
72. 5. Read following paragraph carefully and answer the question given after this paragraph:
73. Write 2 features of JAVA specifically defined / discussed in above paragraph.
74. package one;
75. class A
76. {}
77. package two;
78. class B extends A
79. {}
80. package one;
81. public class A
82. {
83.  protected A(int x)
84.  {
85.  //protected constructor
86.  }
87. }
88. package two;
89. import one.A;
90. class B extends A
91. {
92.  public B()
93.  {
94.  super(100); //calling super class's protected constructor
95.  }
96. }
97. JVM stands for Java Virtual Machine. Java code is compiled down into an intermediary
98. language called byte code. The Java Virtual Machine is then responsible for executing this
99. byte code. This is unlike languages such as C++ which are compiled directly to native code
100. for a specific platform. This is what gives Java its ‘Write once, run anywhere’ ability.
101. Page 4 of 4
102. QUESTION NO. 3 (logic development) (2+2+1=05 Mark)
103. Sparse matrices are matrices whose elements are predominantly zero. This question develops a Java
104. representation for them called SparseMatrix. The code below seeks to use an ArrayList of LinkedLists
105. to implement the concept efficiently. It defines a class Element to store the column number and value
106. for an element. Each row is represented by a LinkedList of Elements with non-zero values only. Few, if
107. any, rows are all zeros and so the ArrayList is used to store a LinkedList for every row in ascending row
108. order. Read the given code carefully and answer the given questions:
109.  
110. public class Element
111. {
112. public int column;
113. public int value;
114. }
115. public class SparseMatrix
116. {
117. private int mRows; // Number of rows
118. private int mCols; // Number of columns
119. private ArrayList<LinkedList<Element> > mMatrix; // Data
120. }
121.  
122. 1. Give two reasons why Element should not have public state and provide a better mutable
123. Element definition.
124. 2. Explain why ArrayList and LinkedList are appropriate choices in this context. And if this is not an
125. appropriate choice then which technique you will use to create a sparse matrix.
126. 3. Write a constructor for SparseMatrix that takes arguments specifying the number of rows and
127. columns and initializes state appropriately.
128. ************************End of Paper**********************
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