Material From System Analysis and Design Ch2

39. The Unified Modeling Language (UML) represents an object as a _____ with the object name at the top, followed by the object’s attributes and methods. a. circle b. rectangl e c. pentago n d. rhombus b ANSWER: UML represents an object as a rectangle with the object name at the top, RATIONALE: followed by the object’s attributes and methods. 40. In an object-oriented system, objects can _____ certain attributes from other objects. a. broadcast b. concatenat e c. inherit d. reformat c ANSWER: In an O-O system, objects can inherit, or acquire, certain attributes from RATIONALE: other objects. 41. The _____ of an object is an adjective that describes the object’s current status. a. polymorphis m b. encapsulation c. resemblance d. state d ANSWER: RATIONALE: The state of an object is an adjective that describes the object’s current status. 42. A bank account object can have a specific attribute called a(n) _____ that can be active, inactive, closed, or frozen. a. state b. grade c. instance d. status ANSWER: a RATIONALE: The state of an object is an adjective that describes the object's current status. For example, a bank account can be active, inactive, closed, or frozen. 43. A(n) _____ resembles a verb and defines specific tasks that an object can perform. a. attribute b. method c. command d. message ANSWER: b RATIONALE: Methods resemble verbs that describe what and how an object does something. 44. A _____ is a command that tells an object to perform a certain method. a. dictum b. message c. pledge d. pronouncemen t b ANSWER: A message is a command that tells an object to perform a certain RATIONALE: method. 45. The concept that a message gives different meanings to different objects is called _____. a. encapsulation b. dynamic addressing c. polymorphism d. linear addressing c ANSWER: The concept that a message gives different meanings to different RATIONALE: objects is called polymorphism. 46. An object can be viewed as a(n) _____, because a message to the object triggers changes within the object without specifying how the changes must be carried out. a. black box b. class diagram c. use case d. activity diagram ANSWER: a RATIONALE: An object can be viewed as a black box, because a message to the object triggers changes within the object without specifying how the changes must be carried out. 47. The black box concept is an example of _____, which means that all data and methods are self-contained. a. polymorphism b. inheritance c. encapsulation d. use case modeling c ANSWER: The black box concept is an example of encapsulation, which means that RATIONALE: all data and methods are self-contained. 48. _____ allows objects to be used as modular components anywhere in a system. a. Dynamic addressing b. Technical feasibility c. Encapsulation d. Linear addressing ANSWER: RATIONALE: c Encapsulation allows objects to be used as modular components anywhere in the system, because objects send and receive messages but do not alter the internal methods of other objects. 49. A major advantage of object-oriented (O-O) designs is that systems analysts can save time and avoid errors by using _____ objects. a. dynamic b. feasible c. modular d. linear ANSWER: c RATIONALE: A major advantage of O-O designs is that systems analysts can save time and avoid errors by using modular objects, and programmers can translate the designs into code, working with reusable program modules that have been tested and verified. 50. All objects within a(n) _____ share common attributes and methods. a. catalog b. register c. index d. class ANSWER: d All objects within a class share common attributes and methods. RATIONALE: 51. Objects within a class can be grouped into _____, which are more specific categories within a class. a. grids b. units c. subclasses d. matrices ANSWER: c Objects within a class can be grouped into subclasses, which are more RATIONALE: specific categories within a class. 52. A class can belong to a more general category called a _____. a. superclas s b. register c. subclass d. catalog a ANSWER: A class can belong to a more general category called a superclass. RATIONALE: 53. _____ enable objects to communicate and interact as they perform business functions and transactions required by a system. a. Aggregates b. Relationships c. Clusters d. Linkages ANSWER: b RATIONALE: Relationships enable objects to communicate and interact as they perform 54. _____ describe what objects need to know about each other, how objects respond to changes in other objects, and the effects of membership in classes, superclasses, and subclasses. a. Instances b. Relationships c. Aggregates d. Clusters ANSWER: b RATIONALE: Relationships describe what objects need to know about each other, how objects respond to changes in other objects, and the effects of membership in classes, superclasses, and subclasses. 55. Inheritance enables an object, called a _____, to derive one or more of its attributes from a parent. a. child b. user c. package d. suite ANSWER: a Inheritance enables an object, called a child, to derive one or more of its RATIONALE: attributes from another object, called a parent. 56. An _____ shows the objects and how they interact to perform business functions and transactions. a. object relationship diagram b. object precedent chart c. object antecedent chart d. object interaction diagram ANSWER: a An object relationship diagram shows the objects and how they interact to RATIONALE: perform business functions and transactions. 57. A(n) _____ represents the steps in a specific business function or process. a. relationship diagram b. use case c. data flow unit d. interaction diagram ANSWER: RATIONALE: process. b A use case represents the steps in a specific business function or 58. In a use case, an external entity, called a(n _____, initiates a use case by requesting the system to perform a function or process. a. beneficiar y b. user c. domain d. actor ANSWER: d RATIONALE: In a use case, an external entity, called an actor, initiates a use case by requesting the system to perform a function or process. 59. The Unified Modeling Language (UML) symbol for a use case is a(n) _____ with a label that describes the action or event. a. rectangle b. triangle c. dashed line d. oval ANSWER: d RATIONALE: The UML symbol for a use case is an oval with a label that describes the action or event. 60. In a use case, the _____ is shown as a stick figure with a label that identifies its role. a. actor b. association c. linkage d. service request ANSWER: a RATIONALE: The actor is shown as a stick figure, with a label that identifies the actor’s role. 61. The line from the actor to the use case is called a(n) _____. a. association b. aggregatio n c. lifeline d. observation ANSWER: a RATIONALE: The line from the actor to the use case is called an association. 62. For each use case, a _____ in the form of a table is developed to document the name of the use case, the actor, a description of the use case, and so forth. a. use case description b. use case diagram c. use case schematic d. use case outline ANSWER: a RATIONALE: For each use case, a use case description in the form of a table is developed to document the name of the use case, the actor, a description of the use case, and so forth. 63. A _____ is a visual summary of several related use cases within a system or subsystem. a. use case description b. use case diagram c. use case schema d. use case matrix ANSWER: b RATIONALE: A use case diagram is a visual summary of several related use cases within a system or subsystem. 64. When a use case diagram is created, the first step is to identify the system boundary, which is represented by a _____. a. triangle b. circle c. rectangl e d. square ANSWER: c RATIONALE: When a use case diagram is created, the first step is to identify the system boundary, which is represented by a rectangle. 65. For a use case diagram, the _____ shows what is included in the system and what is not included in the system. a. system design b. system boundary c. system layout d. system matrix ANSWER: b RATIONALE: The system boundary shows what is included in the system (inside the rectangle) and what is not included in the system (outside the rectangle). 66. A(n) _____ shows the object classes and relationships involved in a use case. a. class diagram b. association diagram c. use case diagram d. modeling diagram ANSWER: a RATIONALE: A class diagram shows the object classes and relationships involved in a use case. 67. In a class diagram, each class appears as a(n) _____, with the class name at the top, followed by the class’s attributes and methods. a. rectangl e b. circle c. oval d. triangle ANSWER: a RATIONALE: In a class diagram, each class appears as a rectangle, with the class name at the top, followed by the class’s attributes and methods. 68. _____ describes how instances of one class relate to instances of another class. a. A modifier b. A deliverable c. Scope d. Cardinality ANSWER: d RATIONALE: Cardinality describes how instances of one class relate to instances of another class. 69. The Unified Modeling Language (UML) notation _____ identifies a zero or many relation. a. 0..1 b. 1..* c. 0..* d. 0..0 ANSWER: c RATIONALE: The UML notation 0..* identifies a zero or many relation. 70. A _____ graphically documents a use case by showing the classes, the messages, and the timing of the messages. a. state transition diagram b. sequence diagram c. data flow diagram d. scatter diagram ANSWER: b RATIONALE: A sequence diagram graphically documents the use case by showing the classes, the messages, and the timing of the messages. 71. In a sequence diagram, a lifeline is identified by a _____ line. a. solid b. dashed c. red d. curved ANSWER: b RATIONALE: A lifeline is identified by a dashed line. 72. In a sequence diagram, a _____ represents the time during which an object above it is able to interact with the other objects in the use case. a. focus point b. schematic matrix c. validity link d. lifeline ANSWER: d RATIONALE: The lifeline represents the time during which the object above it is able to interact with the other objects in the use case. 73. A _____ shows how an object changes from one state to another, depending on events that affect the object. a. state transition diagram b. case tools diagram c. scatter diagram d. business process diagram ANSWER: a RATIONALE: A state transition diagram shows how an object changes from one state to another, depending on events that affect the object. 74. A(n) _____ resembles a horizontal flowchart that shows the actions and events as they occur. a. state transition diagram b. sequence diagram c. business model diagram d. activity diagram ANSWER: d RATIONALE: An activity diagram resembles a horizontal flowchart that shows the actions and events as they occur. Critical Thinking Questions 6-1 Kevin, the trainee analyst at Lynach TechSystems, is in charge of allocating suitable Unified Modeling Language (UML) notations to a particular class diagram. 75. In a given diagram, Kevin is designing a relationship in which a given employee can have no payroll deductions or he/she can have many deductions. Which of the following notations should Kevin write to mark this relationship? a. 0..1 b. 1 c. 0..* d. 1..* ANSWER: c RATIONALE: 0..* identifies a zero or many relation. The example is that an employee can have no payroll deductions or many deductions. Essay 76. What do relationships enable objects to do? What is the strongest kind of relationship? Walk through an example that demonstrates your understanding of the concept. Relationships enable objects to communicate and interact as they perform ANSWER: business functions and transactions required by the system. Relationships describe what objects need to know about each other, how objects respond to changes in other objects, and the effects of membership in classes, superclasses, and subclasses. Some relationships are stronger than others (just as a relationship between family members is stronger than one between casual acquaintances). The strongest relationship is called inheritance. Inheritance enables an object, called a child, to derive one or more of its attributes from another object, called a parent. As one example, the INSTRUCTOR object (child) inherits many traits from the EMPLOYEE object (parent), including SOCIAL SECURITY NUMBER, TELEPHONE NUMBER, and HIRE DATE. The INSTRUCTOR object also can possess additional attributes, such as TYPE OF INSTRUCTOR. Because all employees share certain attributes, those attributes are assumed through inheritance and do not need to be repeated in the INSTRUCTOR object. RUBRIC: Criteria Student describes what relationships enable objects to do, identifies the strongest kind of relationship, and uses an example that demonstrates understanding. 0 1 2 3 4 Failure Below Expectations Developing Competent Mastery 77. Explain a class diagram. Also, explain how a class diagram is like a data flow diagram (DFD). ANSWER: A class diagram shows the object classes and relationships involved in a use case. Like a DFD, a class diagram is a logical model, which evolves into a physical model and finally becomes a functioning information system. In structured analysis, entities, data stores, and processes are transformed into data structures and program code. Similarly, class diagrams evolve into code modules, data objects, and other system components. In a class diagram, each class appears as a rectangle, with the class name at the top, followed by the class’s attributes and methods. Lines show relationships between classes and have labels identifying the action that relates the two classes. To create a class diagram, you review the use case and identify the classes that participate in the underlying business process. The class diagram also includes a concept called cardinality, which describes how instances of one class relate to instances of another class. For example, an employee might have earned no vacation days or one vacation day or many vacation days. Similarly, an employee might have no spouse or one spouse. RUBRIC: Criteria Student explains a class diagram and how a class diagram is like a data flow diagram (DFD). 0 1 2 3 4 Failure Below Expectations Developing Competent Mastery 78. Explain why tools are used in object modeling. ANSWER: Object modeling requires many types of diagrams to represent the proposed system. Creating the diagrams by hand is time consuming and tedious, so systems analysts rely on tools to speed up the process and provide an overall framework for documenting the system components. In addition, tools ensure consistency and provide common links so that once objects are described and used in one part of the design, they can be reused multiple times without further effort. RUBRIC: Criteria 0 1 2 3 4 Failure Below Expectations Developing Competent Mastery Student explains why tools are used in object modeling. 79. Using the concept of polymorphism, define messages. ANSWER: A message is a command that tells an object to perform a certain method. For example, the message PICK UP TOYS directs the CHILD class to perform all the necessary steps to pick up the toys. The CHILD class understands the message and executes the method. The same message to two different objects can produce different results. The concept that a message gives different meanings to different objects is called polymorphism. For example, the message GOOD NIGHT signals the PARENT object to read a bedtime story, but the same message to the CHILD object signals it to get ready for bed. If the family also had a DOG object, the same message would tell the dog to sleep. RUBRIC: Criteria 0 1 2 3 4 Failure Below Expectations Developing Competent Mastery Using an example of the concept of polymorphism, student defines messages. 80. Define encapsulation using the black box concept. The black box concept is an example of encapsulation, which means that ANSWER: all data and methods are self-contained. A black box does not want or need outside interference. By limiting access to internal processes, an object prevents its internal code from being altered by another object or process. Encapsulation allows objects to be used as modular components anywhere in the system, because objects send and receive messages but do not alter the internal methods of other objects. RUBRIC: 0 1 2 3 4 Failure Below Expectations Developing Competent Mastery Criteria Student defines encapsulation using the black box concept.