01
True or false
1 point
True or false: In object-oriented design, composition expresses a has-a relationship between objects.
Free Practice Quiz Question List
7 Composition and Delegation Online Quiz Questions
Use this free practice quiz with 20 questions to review 7 Composition and Delegation, test your knowledge, and prepare for your next test or exam.
20 questions
02
Choose one
1 point
Which situation best illustrates delegation?
- A
A class stores a collaborator but performs every operation itself.
- B
A class receives a request and asks a collaborator to carry out the operation.
- C
A subclass inherits fields from its superclass.
- D
A class creates all of its parts internally.
03
Choose one
1 point
A service receives a collaborator as a constructor parameter instead of creating it internally. What design technique is being used?
- A
The class creates a concrete dependency inside its method.
- B
The class receives its dependency through its constructor.
- C
The class inherits the dependency's implementation.
- D
The class accesses the dependency's private fields directly.
04
Choose all
1 point
An AccountService depends on the NotificationSender interface rather than on EmailSender. Which two benefits follow from this design? Select all correct choices.
- A
The collaborator can be replaced by another implementation.
- B
The containing class automatically becomes a subtype of the collaborator.
- C
The same service can work with different implementations such as email or SMS.
- D
The collaborator's private fields become directly accessible.
05
Choose one
1 point
In the material's distinction between strong and weak composition, what is characteristic of weaker composition?
- A
The component may be shared or replaced by the caller.
- B
The component must be created and destroyed only by the containing object.
- C
The component must be a superclass of the containing object.
- D
The component's fields must be public.
06
True or false
1 point
True or false: Because WeatherStation collaborates with TemperatureSensor through its public operations, it can remain independent of the sensor's private representation.
- A
True
- B
False
07
Choose all
1 point
Which two situations favor composition over inheritance? Select all correct choices.
- A
The relationship is naturally uses-a rather than is-a.
- B
The subtype fully satisfies a stable superclass contract.
- C
The behavior may need to vary independently of the containing class.
- D
The main goal is to expose every inherited method.
08
Written response
1 point
What relationship does inheritance express between a subclass and its superclass?
09
Written response
1 point
What design pattern is illustrated when UserAccount contains a replaceable NotificationPolicy and delegates notification behavior to it?
10
Fill in the blank
1 point
Complete the statements: When one object passes responsibility for carrying out an operation to another object, this is called . The object performing the delegated work is the .
11
Fill in the blank
1 point
Complete the comparison: Composition most directly represents a relationship, whereas inheritance most directly represents an relationship.
12
Open ended
1 point
A developer proposes making Report extend Printer solely because reports can be printed. Explain the design you would recommend and why it better represents the relationship.
13
Choose one
1 point
An application may support email, SMS, push, and in-app notifications, and the notification mechanism may change independently of the account. Which design best addresses this requirement?
- A
Give UserAccount a NotificationPolicy collaborator and delegate notification to it.
- B
Create a separate UserAccount subclass for every notification mechanism.
- C
Make UserAccount directly implement every notification protocol.
- D
Copy the notification implementation into each account method.
14
Choose one
1 point
Which condition is most important when deciding whether inheritance is appropriate?
- A
The subclass can reuse any convenient implementation detail.
- B
The subclass genuinely satisfies the supertype's meaning and contract.
- C
The subclass exposes more methods than its superclass.
- D
The subclass avoids having any collaborators.
15
Choose one
1 point
Which statement correctly describes the relationship between Car and Engine in the composition example?
- A
A
Caris anEngine. - B
A
Carhas anEngine. - C
An
Engineis aCar. - D
A
Carinherits all ofEngine's implementation.
16
Choose one
1 point
A class creates its own OrderLine objects and controls how long they exist. What kind of composition does this illustrate?
- A
The contained object is always shared by unrelated objects.
- B
The contained object must implement an interface.
- C
The containing object creates and controls the lifetime of its part.
- D
The containing object can never replace its part.
17
True or false
1 point
True or false: When a class uses composition to contain another object, the containing class automatically becomes a subtype of the contained object's class.
- A
True
- B
False
18
Written response
1 point
In the redesigned UserAccount, notification behavior is supplied through a replaceable NotificationPolicy object. What design pattern does this illustrate?
19
Choose one
1 point
Why does declaring AccountService.sender as a NotificationSender make the service flexible?
- A
It must create a separate
AccountServicesubclass for every notification channel. - B
It can collaborate with different implementations of
NotificationSender. - C
It can access the private fields of every sender implementation.
- D
It eliminates the need for any object to implement
send.
20
Written response
1 point
What principle requires a subtype to remain usable wherever its superclass is expected?