OOP Midterm

Question 1

Uses-a types (3)

Answer 1

Dependency

Association

Direct Association

Question 2

Has-a types (2)

Answer 2

Aggregation

Composition

Question 3

Is-a types (1)

Answer 3

Inheritance

Question 4

Implements-a types (1)

Answer 4

Interface Implementation (realization)

Question 5

Dependency

Answer 5

transient relationship between two classes. Implementation of class A that uses class B does not affect class A definition

Class B is unaware of the existence of the class A (Asymmetry)

(Minimize this relationship to reduce coupling)

Question 6

Association

Answer 6

relationship between Class A and Class B last as long as both object live at runtime. One class is owned by the object of another class

Question 7

dependency example

Answer 7

A method of class Sequence uses a Stack class to verify palindrome. A student enrollment class uses a student class in its method

i.e. A method of class A is passed as parameter of class B and returns a value of class B.

Question 8

association example

Answer 8

A teacher class has a method to assign students to a class while students can (or can not) specify which teacher is teaching their class

i.e. class A has an attribute that is class B

Question 9

cardinality

Answer 9

Defines multiplicity between objects (one-to-one, one-to-many…)

Question 10

direct association

Answer 10

A strong connection between classes where both classes are generally aware of each other and have direct references or attributes that link them

Question 11

direct association example

Answer 11

A teacher class where each student is defined a specific teacher and each teacher has a direct reference to their student. Both classes are aware of each other

Question 12

association subtypes

Answer 12

aggregation

Question 13

composition

Answer 13

A child class that cannot exist independently of its parent class

Question 14

composition example

Answer 14

Class car has a class Engine. Since Car owns Engine, it controls the lifetime of this class meaning once Car is destroyed, so is Engine

Question 15

aggregation

Answer 15

Child class is independent of its parent class meaning its a standalone and unidirectional class that can exist independent of it’s parent class. Association is unidirectional.

Question 16

aggregation example

Answer 16

Class University aggregates Class department objects. The department objects can exist independently of the university

i.e. Class A contain objects of class B over period of time. Both objects survive individually

Question 17

restricted form of aggregation

Answer 17

composition

Question 18

composition

Answer 18

Class A composes or owns class B and represents “part-of” relationship. Class B cannot have an existence without Class A (High dependency)

Question 19

Inheritance

Answer 19

Class B is derived and dependent on Class A. Class B can access and utilize members of Class A and extend or specialize behavior of Class A

Question 20

Interface Implementation

Answer 20

Class B is a realization of interface A. Class B must override all Class A methods

Question 21

Expansion

Answer 21

Mechanism for building on top of existing classes. Building upon capabilities of class A in class B

Question 21

Contraction

Answer 21

Specializing and narrowing down the capabilities of a class. Class B restricts or refines behaviors or attributes of inherited Class A

Question 21

transative

Answer 21

A property of relationship that extends from one element to another through a series of elements.

i.e. Class A is related to Class B and Class B is related to Class C so Class A is related to Class C

Question 21

concept reuse in inheritance

Answer 21

Class B can override behavior of parent class. Class B shares definitions of methods but not implementations

Question 21

code reuse in inheritance

Answer 21

Class B inherits behavior from Class A

Question 22

Contractual Obligation

Answer 22

Overridden method sis required to keep the same name, return type, and parameters as the base class

Question 22

override

Answer 22

Method replacement keyword that tells compiler to replace a method from inherited base class with its derived class’s implementation

Question 23

abstract class

Answer 23

a restricted class that acts similar to an interface and can have both abstract and regular methods

Question 24

abstract method

Answer 24

Can only be used in an abstract class and it does not have implementation

Question 25

Forms of Inheritance (8)

Answer 25

Specialization
Specification
Construction
Generalization
Extension
Limitation
Variance
Combination

Question 26

Specialization

Answer 26

Child class is a special case of parent class

Question 27

Specification

Answer 27

The parent class defines behavior that is implemented in the child class but not in the parent class.

Parent class can be an abstract class or interface and child class is a realization of the parent

Question 28

Construction

Answer 28

Child class makes use of parent’s behavior but is not a subtype of the parent (breaks principle of substitution)

Question 29

Principle of Substitution

Answer 29

subclass is a subtype of the parent meaning the object type associated with a value held by a variable may not exactly match the type associated with the declaration for that variable

Shape s = Triangle t;

Question 30

Generalization

Answer 30

Child class modifies or overrides some methods of its parent class (opposite of subclassing for specialization)

must override one method from parent

Question 31

Extension

Answer 31

Child class adds new functionality to the parent class but does not change inherited behavior

no modifications to parent methods, new methods are owned by the child class

Question 32

Variance

Answer 32

The child class and parent class are variants of each other, and the the class-subclass relationship is arbitrary

Two or more classes have similar implementations but do no posses any hierarchical relationship between the concepts represented by the classes

Question 33

Multiple (Combination)

Answer 33

The child class inherits features from more than one parent class.

i.e. inherits from parent class and implements multiple interfaces

Question 34

benefits of inheritance

Answer 34

software reuse
consistency of interface
rapid prototyping
polymorphism
information hiding

Question 35

polymorphism

Answer 35

permits programmer to generate high-level reusable components that can be tailored to fit different applications by changes in their low-level parts

Question 36

Inheritance Disadvantages

Answer 36

Execution Speed
Program size
Message Passing Overhead
Program Complexity

Question 37

Execution Speed

Answer 37

Inherited methods deal with arbitrary subclasses are often slower than specialized code

Question 38

Limitation

Answer 38

The child class restricts the use of inherited parent class behavior