Download OOP SBA Test - Memo - Beaulieu College`s Intranet

BEAULIEU COLLEGE
INFORMATION TECHNOLOGY
OOP SBA Test – 2016
GRADE 12
Time: 45 min
Examiner: F. D. Khan
Marks: 40
Moderator : Elaine Emmet
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INSTRUCTIONS


Answer ALL questions on the question paper.
This question paper consists of 7 pages. Please check that your paper is complete
___________________________________________________________________________________________________
NAME OF LEARNER: ____________________________________________________
Question 1
1.
An object definition class usually has a number of fields that describe the
characteristics of the object. These fields are usually prefixed with an access
Modifier
1.1
List the names of two access modifiers that you have used and explain their
functionality in a program.
(2)
Public and private, public means the code is accessible outside of the class while
private means that the code is only accessible from inside of the class.
1.2
Explain the purpose of using mutator (setters) methods in a class?
(1)
The purpose of mutator methods is to change the values of private fields in a class.
1.3
Differentiate between a class provider and a class user.
(2)
The class provider is the programmer who codes the class and the class user is a
programmer who instantiates an object of the class.
1.4
What is a helper method and what is its significance?
(2)
Helper methods are private methods that are called by public methods. They are
used to add functionality to a class.
1.5
What is encapsulation in relation to programming in either Java or Delphi?
(1)
Encapsulation occurs when a class combines the fields and methods into one unit of
code
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Question 2
Algorithms and Pseudo Code
2.1
What is an algorithm?
(1)
An algorithm is a sequence of instructions, that if followed will result in a single
programming problem being solved by following specific steps.
2.2
What is the purpose of writing in Pseudo Code?
It allows the designer to focus on the logic of the algorithm without being distracted by
details of language syntax
(2)
2.3
Consider the following Java and Delphi code below.
Public class HodgePodge()
{
getWritingStuff();
OpenStudyGuide();
OpenClassworkBook();
for ( int x= 0; x <= 9; x++)
{
question[x].solve();
while( !question[x].isDoneCorrectly())
{
this.removeAnswer(x);
question[x].solveThisProblem();
}
allComplete();
submit();
}
}
Unit HodgePodge;
Interface …
implementation
Function getWritingStuff;
Procedure OpenStudyGuide;
Procedure OpenClassworkBook;
for x := 0 to 9 do
begin
question[x].solve;
while( NOT question[x].isDoneCorrectly) do
begin
removeAnswer(x);
question[x].solveThisProblem;
end;
allComplete;
submit;
end;
end.
Nathaniel, is having some difficulty understanding the code that has been created for
the HodgePodge class/Unit. You have taken it upon yourself to help him understand
the code by converting this code to Pseudo Code. Write a simple algorithm in Pseudo
Code that you will give to Nathaniel to help him in his understanding of the
abovementioned class.
(4)
method Hodgepodge()
get Writing stuff
open StudyGuide and ClassWorkbook
work through ALL 10 of the questions
begin
solve the questions
while the questions are not done correctly
try again
end
complete everything
submit your work
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Question 3
Objects, constructors and the toString method/function
3.1
Differentiate between a default constructor and a parameterised constructor?
(2)
The purpose of a constructor is to add values to the fields of an object, the default
constructor assigns default values to the fields of an object chosen by the class provider
whilst a parameterized constructor assigns values to the fields of an object as arguments
inside brackets of the constructor method which are passed to the constructor from the
call statement.
3.2
What is required in order for you to instantiate an object of a class? Write a line of code
to show how instantiation of an object can be achieved.
(2)
An object gets created in Java by using the new operator and calling the constructor of a
class. Gogga bug = new gogga() or similar for Delphi
3.3
What is the purpose of a toString method/function in a class?
(1)
The toString() method is used when we need a string representation of an object and is
usually coded in a class.
3.4
What will happen if a constructor method is not coded in a class?
(1)
A default constructor is automatically created
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Question 4
4.1
Consider the following class diagram
Member
Properties/Fields:
‒
‒
‒
‒
String name
String Surname
String Address
Email emailAddr
Methods:
+
+
+
+
+
+
Constructor(String nme, String Sname, String Addr, Email emailad)
getName : String
getsurname : String
getAddress : String;
setSurname(String s)
toString() : String
A program can have many objects and they all need to interact with one another in different
ways. This is achieved either through Inheritance or Composition. Inheritance refers to when
you extend all the properties and methods of a parent class into a child class. Composition refers
to when a class only uses certain objects from another class.
The class above uses Composition and one of its attributes, emailAddr, is an object from the
Email class.
4.1.1 Write code to create a constructor method that will initialise all the properties/fields
of the Member class.
(3)
Java
public Member(String nme, String sn, String add, Email emailad)
{
name = nme;
surname = sn;
address = add;
emailAddr = emailad;
}
Delphi
constructor TMember.Create (nme: String, sn:String, add:String, emailad:Email);
begin
name := nme;
surname := sn;
address := add;
emailAddr := emailad;
end;
4.1.2 The attribute emailAddr, is an object of the Email class (not shown here). Write down
TWO possible attributes of the Email class.
JAVA
(2)
private String to;
private String from;
DELPHI
Private to:String;
Private from:String;
4.1.3 Besides the constructor and toString methods, the Email class may have other methods.
Write down the method headers for THREE other methods of the Email class.
(3)
JAVA
public void setEmail() {}
public String getEmail() {}
public String sendEmail() {}
DELPHI
Procedure TMember.setEmail
Function TMember.getEmail:String;
Function TMember.sendEmail:String;
4.2
Arrays play a huge part in programming because they allow us to manipulate data
structures in primary memory.
4.2.1 What is the purpose of an array index or subscript?
A symbol or a number used to identify an element in an array. Usually, the
subscript is placed in brackets following the name of the array.
(1)
4.2.2 How would you use an array in programming to store an unknown number
of data items?
(1)
Use an ArrayList or listIterator
4.2.3 An object called Patient with a name, age, gender and procedure (eg. Colonoscopy, heart
bypass, appendix removal) fields, exists.
(5)
A Patientmanager has the following declaration:
Patient [ ] Arr = new patient [50]
…
in Java
Arr : Array [1..50] of TPatient;
…
in Delphi
Write Pseudocode to sort the array in ascending order according to the procedure
field. Use a method.
Subprogram Sort
Temp : Patient
Begin
For j = 0 to counter -2
Begin
For i = j+1 to counter -1
Begin
If Arr[j].getProcedure > Arr[i].getProcedure
Then
Begin
Temp = Arr[j]
Arr[j] = Arr[i]
Arr[i] = Temp
End;
End;
End;
End;
4.4
Static and Non-static Methods
A class called Vehicle, a method called tint and an object called window are given.
4.4.1 How would you call the static method using dot notation?
(2)
Vehicle.tint
4.4.2 How would you call the non-static method using dot notation?
(2)
Window.tint
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