Exam paper for first semester: Object Oriented Programmin

University of Johannesburg

University of Johannesburg Institutional Repository

FACULTY OF SCIENCEACADEMY OF COMPUTER SCIENCE AND SOFTWARE ENGINEERINGMODULE CSC2A10OBJECT ORIENTED PROGRAMMINGCAMPUS AUCKLAND PARK CAMPUS (APK)EXAM JUNE 2014DATE 09/06/2014 SESSION 8:30-10:30ASSESOR(S) MR DT VAN DER HAARMR A MAGANLALINTERNAL MODERATOR DR ID ELLEFSENDURATION 2 HOURS MARKS 100NUMBER OF PAGES: 7 PAGESINSTRUCTIONS: ANSWER ALL THE QUESTIONSREQUIREMENTS: AN EXAM BOOK FOR THE STUDENT1CSC2A10 — June 2014SECTION A - TheoryQUESTION 1Java Basics(a) [3]Name the programming language class the source code below belongs to and list twoadvantages it has over other programming classes.1 c l a s s F r u i t implements C lonab l e {23 p r i v a t e S t r i n g f ru i tName ;4 p r i v a t e f l o a t we ight ;56 p u b l i c F r u i t ( ) {7 }89 p u b l i c se tFru i tName ( S t r i n g name) {10 t h i s . f ru i tName = name ;11 }1213 p u b l i c getFru i tName ( ) {14 r e t u r n f ru i tName ;15 }1617 p u b l i c s e t F r u i tWe i g h t ( double we ight ) {18 t h i s . we ight = we ight ;19 }2021 p u b l i c ge tF ru i tWe i gh t ( ) {22 r e t u r n we ight ;23 }2425 p u b l i c S t r i n g t o S t r i n g ( ) {26 r e t u r n S t r i n g . fo rmat ( ”%s :%.2 f ” , f r u i t C o l o r , we ight ) ;27 }(b) [4]By analysing the above source code, what are differences we can see between this languageand C++?(c) [3]What is a pure-virtual function? List 1 reason why using it can cause problems in programs.[10]QUESTION 2Elementary Java Programming(a) [4]In Java, what is the storage size of a short and float? What makes the data types in Javadifferent from C++?(b) [4]Briefly describe what the dangling else problem is and describe how it can be avoided.(c) [2]Briefly explain pass-by-sharing within the context of methods in Java.[10]2CSC2A10 — June 2014QUESTION 3(a) [3]Briefly describe variable length parameter lists. Provide a short Java source codesegment that demonstrates this concept.(b) [2]What is a Lliffe vector?(c) [3]Classify the Bubble Sort algorithm in terms of:• Computational complexity• Memory usage• Iterative versus recursive approach[8]QUESTION 4Text Processing and Persistence(a) [3]What occurs in the Java source code below? What is this called?1 p u b l i c c l a s s Test {2 p u b l i c vo id s t a t i c main ( S t r i n g [ ] a r g s ) {3 S t r i n g s1 = ”Test ” ;4 S t r i n g s2 = ”Test ” ;56 i f ( s1==s2 ) {7 System . out . p r i n t l n ( ” Proof ! ” ) ;8 }9 e l s e {10 System . out . p r i n t l n ( ” F a i l e d ” ) ;11 }12 }13 }(b) [1]Aside from the Scanner class, name another stream class that can be used for text reading.(c) [4]Provide a regular expression that provides the following match result (you do not haveto provide Java source code):[8]3CSC2A10 — June 2014QUESTION 5Object Orientation(a) [3]List 3 requirements a class must conform to in order for it to be an immutable class.(b) [2]Dynamic binding is required in order to achieve polymorphism. What is dynamic binding?(c) [3]List 3 properties of abstract classes.[8]QUESTION 6Graphical User Interfaces(a) [4]What is a layout manager and why is it useful? Name 2 examples that can be found inJava.(b) [4]Analyse the Java source code below and list any problems found.1 p u b l i c c l a s s Test extends j a v a x . swing . JFrame{23 p u b l i c Test ( ) {4 j a v a x . swing . JButton btn = new JButton ( ”Test ” ) ;5 addAc t i o nL i s t e n e r (new L i s t e n e r ) ;6 add (new j a v a x . swing . JLabe l ( ” C l i c k Test ” ) ) ;7 s e t S i z e (100 ,200) ;8 s e t V i s i b l e ( f a l s e ) ;9 }1011 p u b l i c s t a t i c vo id main ( S t r i n g [ ] a r g s ) {12 new t e s t ( ) ;13 }1415 c l a s s L i s t e n e r {16 p u b l i c vo id ac t i onPe r f o rmed ( Act ionEvent e ) {17 System . out . p r i n t l n ( ”Test has been c l i c k e d ” ) ;18 }19 }[8]QUESTION 7Advanced Java Programming(a) [2]Briefly explain what an assertion is and where it is used.(b) [3]Describe the 3 wild card formats supported for generics in Java.(c) [3]Name 3 states an applet in Java can transition/move into in the applet life cycle.[8]4CSC2A10 — June 2014QUESTION 8Design Patterns(a) [4]Briefly describe how the following design patterns work:1. Facade2. Adapter3. Visitor4. Singleton(b) [6]An online shoppping company, which sells Products explicitly caters to Gamers, has ap-proached you to provide them with the ability to notify Gamers when Video Games areavailable in the country. Using best practices (such as appropriate object encapsulation anddesign patterns) provide a class diagram that would help the company to their Customer ’sneeds.[10]SECTION B - PracticalQUESTION 9Provide Java source code for a paintComponent function which will draw a blue rectangle ofsize 50 x 50.[10]QUESTION 10Provide Java source code for a function to read from a binary file called code.bin. The filecontains a integer followed by a string followed by two more integers. Display each piece of datato the standard output stream. Remember to include any necessary exception handling. Youcan assume that all necessary packages have been imported.[10]QUESTION 11Read the code below and provide the missing code (in the segments labelled as A to G).1 import j a v a . u t i l . A r r a y L i s t ;2 import j a v a . u t i l . Random ;34 c l a s s RacingTeam implements (A (2 marks ) )5 {6 p r i v a t e f i n a l Random randGen=new Random ( ) ;7 p r i v a t e f i n a l S t r i n g teamName ;8 p r i v a t e long t ime ;910 p u b l i c RacingTeam ( S t r i n g name)11 {12 t h i s . teamName = name ;13 }1415 p u b l i c S t r i n g getName ( )16 {17 r e t u r n teamName ;18 }5CSC2A10 — June 20141920 p u b l i c long getTime ( )21 {22 r e t u r n t ime ;23 }2425 @Over r ide26 p u b l i c (B (1 marks ) ) run ( )27 {28 System . out . fo rmat ( ”%s s t a r t i n g eng i n e%n” , name) ;29 t ime = ( randGen . n e x t I n t (30) + 1) ∗ 10 ;30 t r y31 {32 // S imu la t e r a c i n g t ime33 Thread . (C (2 marks ) ) ( t ime ) ;34 }35 catch ( (D (2 marks ) ) e )36 {37 e . p r i n t S t a c kT r a c e ( ) ;38 }39 System . out . fo rmat ( ”%s f i n i s h e d i n %d%n” , name , t ime ) ;40 }4142 }4344 p u b l i c c l a s s BigRace45 {4647 p u b l i c s t a t i c vo id main ( S t r i n g [ ] a r g s )48 {49 Ar r a yL i s t<RacingTeam> teams = new Ar r a yL i s t <>() ;50 teams . add (new RacingTeam ( ” F e r r a r i ” ) ) ;51 teams . add (new RacingTeam ( ” Force I n d i a ” ) ) ;52 teams . add (new RacingTeam ( ” Lotus ” ) ) ;53 teams . add (new RacingTeam ( ”Maruss i a ” ) ) ;54 teams . add (new RacingTeam ( ”McLaren” ) ) ;55 teams . add (new RacingTeam ( ”Red Bu l l ” ) ) ;56 teams . add (new RacingTeam ( ”Sauber ” ) ) ;57 teams . add (new RacingTeam ( ”Toro Rosso ” ) ) ;58 teams . add (new RacingTeam ( ”Wi l l i ams ” ) ) ;5960 RacingTeam winne r = n u l l ;61 Ar r a yL i s t< (E (1 marks ) ) > t h r e a d s = new Ar r a yL i s t <>() ;6263 f o r ( RacingTeam team : teams )64 {65 Thread t = new Thread ( (F (1 marks ) ) ) ;66 t h r e a d s . add ( t ) ;67 t . s t a r t ( ) ;68 }6970 f o r ( Thread t : t h r e a d s )71 {72 t r y73 {74 t . j o i n ( ) ;75 }76 catch ( I n t e r r u p t e dE x c e p t i o n e )77 {78 e . p r i n t S t a c kT r a c e ( ) ;79 }80 }6CSC2A10 — June 201481 long t ime = Long .MAX VALUE;82 f o r ( RacingTeam team : teams )83 {84 i f ( team . getTime ( ) < t ime )85 {86 winne r = team ;87 t ime = (G (1 marks ) ) ;88 }89 }9091 System . out . p r i n t l n ( ”The winne r i s \ t ” + winne r . getName ( ) ) ;9293 }9495 }[10]The End!7

Object Oriented Programming

FACULTY OF SCIENCEACADEMY OF COMPUTER SCIENCE AND SOFTWARE ENGINEERINGMODULE CSC2A10OBJECT ORIENTED PROGRAMMINGCAMPUS AUCKLAND PARK CAMPUS (APK)EXAM JULY 2014DATE 07/2014 SESSION 8:00-10:00ASSESOR(S) MR DT VAN DER HAARMR A MAGANLALINTERNAL MODERATOR DR ID ELLEFSENDURATION 2 HOURS MARKS 100NUMBER OF PAGES: 6 PAGESINSTRUCTIONS: ANSWER ALL THE QUESTIONSREQUIREMENTS: AN EXAM BOOK FOR THE STUDENT1CSC2A10 — July 2014SECTION A - TheoryQUESTION 1Java Basics(a) [4]List 4 design goals of the Java language.(b) [4]You have been approached by an embedded systems engineer with extensive C++ experi-ence. Discuss the differences between Java and C++ with respect to pointers, primitivedata types, exception handling and multi-threading.(c) [2]Briefly describe what is a JVM.[10]QUESTION 2(a) [4]What are data storage sizes (in bits) for the following data types:1. int2. short3. Object Reference4. byte(b) [4]Name 4 logical operators that can be used in a selection statement.(c) [2]Provide a short Java source code example that demonstrates flow control.[10]QUESTION 3Elementary Java Programming(a) [2]Explain why method overriding is useful for developers.(b) [3]The following Java code segment is for a method that intends to modify a class datamember. Does the method achieve this task? Provide a reason for your answer.1 c l a s s Student {2 p r i v a t e S t r i n g name ;3 p u b l i c vo id setName ( S t r i n g name)4 {5 name = name ;6 }7 }(c) [3]Classify the Selection Sort algorithm in terms of:• Computational complexity• Memory usage for N elements• Iterative versus recursive approach[8]2CSC2A10 — July 2014QUESTION 4Text Processing and Persistence(a) [2]Briefly describe why Strings are said to be immutable in Java.(b) [2]What Java classes will be required for reading the first line of a text file?(c) [4]Provide a regular expression that provides the following match result (you do not haveto provide Java source code):[8]QUESTION 5Object Orientation(a) [3]Analyse the Java source code below. Are there any problems that occur? Provide areason for you answer.1 i n t e r f a c e D i s p l a y a b l e {2 p u b l i c vo id d i s p l a y ( S t r i n g message ) ;3 }45 c l a s s MessageProv ide r implements D i s p l a y a b l e {6 p u b l i c vo id d i s p l a y ( S t r i n g message ) {7 System . out . p r i n t l n ( message ) ;8 }9 }1011 c l a s s Main{12 p u b l i c s t a t i c vo id main ( S t r i n g [ ] a r g s ) {13 D i s p l a y a b l e m = new MessageProv ide r ( ) ;14 m. d i s p l a y ( ”Test ” ) ;15 }16 }(b) [3]Aside from general aggregation, list 3 other types of relationships that can be used whenmodelling UML class diagrams.(c) [2]List 2 properties of an interface.[8]QUESTION 6Graphical User Interfaces(a) [4]Aside from AWT what other graphical user interface framework is provided by Java?Provide 2 properties for this GUI framework.3CSC2A10 — July 2014(b) [4]Discuss how event handling is achieved in Java. Be sure to include all the componentsthat are required.[8]QUESTION 7Advanced Java Programming(a) [4]Provide HTML that can be used to embed an applet (VideoPlayer.class of size 640 by480) into a basic web page.(b) [4]Discuss how exception handling is achieved in Java. You provide Java source code toillustrate your answer.[8]QUESTION 8Design Patterns(a) [4]Provide a UML class diagram that illustrates the Proxy design pattern.(b) [6]Aside from the proxy design pattern, name 3 other design patterns, along with theirlimitations.[10]SECTION B - PracticalQUESTION 9Provide Java source code for a paintComponent function which will draw a green circle ofradius 50.[10]QUESTION 10Provide Java source code for a function to write a binary file called code.bin. The followingdata must be written to file:• The current year (2014)• The string Total• The number 28• The number 5Remember to include any necessary exception handling. You can assume that all necessarypackages have been imported.[10]4CSC2A10 — July 2014QUESTION 11Read the code below and provide the missing code (in the segments labelled as A to G).1 import j a v a . u t i l . A r r a y L i s t ;2 import j a v a . u t i l . Random ;34 c l a s s Conte s t an t implements (A (2 marks ) )5 {6 p r i v a t e f i n a l Random randGen ;7 p r i v a t e f i n a l S t r i n g name ;8 p r i v a t e i n t answer , t ime ;910 p u b l i c Conte s t an t ( S t r i n g name)11 {12 t h i s . name = name ;13 randGen = new Random(name . hashCode ( ) ) ;14 }1516 @Over r ide17 p u b l i c vo id (B (1 marks ) )18 {1920 t ime = ( randGen . n e x t I n t (30)+1) ∗ 10 ;21 t r y22 {23 // S imu la t e t h i n k i n g t ime24 (C (2 marks ) ) . s l e e p ( t ime ) ;25 }26 catch ( (D (2 marks ) ) e )27 {28 e . p r i n t S t a c kT r a c e ( ) ;29 }30 answer = randGen . n e x t I n t (100) ;31 System . out . fo rmat ( ”%s gues sed %d\ t%d%n” , getName ( ) , getAnswer ( ) , getTime ( )) ;32 }3334 p u b l i c S t r i n g getName ( )35 {36 r e t u r n name ;37 }3839 p u b l i c i n t getAnswer ( )40 {41 r e t u r n answer ;42 }4344 p u b l i c i n t getTime ( )45 {46 r e t u r n t ime ;47 }4849 }5051 p u b l i c c l a s s GameShow52 {5354 p u b l i c s t a t i c vo id main ( S t r i n g [ ] a r g s )55 {56 i n t answer = new Random ( ) . n e x t I n t (100) ;5758 Ar r a yL i s t< (E (1 marks ) ) > c o n t e s t a n t s = new Ar r a yL i s t <>() ;5CSC2A10 — July 201459 c o n t e s t a n t s . add (new Conte s t an t ( ”Bob” ) ) ;60 c o n t e s t a n t s . add (new Conte s t an t ( ” S a l l y ” ) ) ;61 c o n t e s t a n t s . add (new Conte s t an t ( ”Thabo” ) ) ;62 c o n t e s t a n t s . add (new Conte s t an t ( ”Mpho” ) ) ;63 c o n t e s t a n t s . add (new Conte s t an t ( ” Ra je sh ” ) ) ;6465 Conte s t an t w inne r = n u l l ;66 Ar r a yL i s t<Thread> t h r e a d s = new Ar r a yL i s t<Thread>() ;67 System . out . p r i n t l n ( ”The answer i s ” + answer ) ;68 whi le ( w inne r == n u l l )69 {7071 f o r ( Conte s t an t c o n t e s t a n t : c o n t e s t a n t s )72 {73 Thread thd = new Thread ( c o n t e s t a n t ) ;74 t h r e a d s . add ( thd ) ;75 (F (1 marks ) ) . s t a r t ( ) ;76 }77 f o r ( Thread thd : t h r e ad s )78 {79 t r y80 {81 thd . j o i n ( ) ;82 }83 catch ( I n t e r r u p t e dE x c e p t i o n e )84 {85 e . p r i n t S t a c kT r a c e ( ) ;86 }87 }88 System . out . p r i n t l n ( ”Check ing gu e s s e s ” ) ;89 f o r ( Conte s t an t c o n t e s t a n t : c o n t e s t a n t s )90 {9192 i f ( w inne r == n u l l && (G (1 marks ) ) == answer )93 {94 winne r = con t e s t a n t ;95 }96 }97 t h r e a d s . c l e a r ( ) ;98 }99 System . out . p r i n t l n ( ”The winne r i s \ t ” + winne r . getName ( ) ) ;100101 }102103 }[10]The End!6

Object Oriented Programming

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University of Johannesburg Institutional Repository

University of Johannesburg Institutional Repository