Chp 2 - Architecting Flutter Apps

Question 1

What is a common consequence of making poor app design decisions due to tight deadlines?

Answer 1

The app becomes harder to maintain long-term (technical debt)

Question 2

List 4 examples of ‘short-term hacks’ in app development.

Answer 2

1. Tailoring to specific devices
2. Blindly copying and pasting code into files
3. Placing all business logic in UI files.
4. Hardcoding user-facing strings in code

Question 3

What is the key benefit of good architecture regarding problem-solving?

Answer 3

It lets you benefit from already-solved problems

Question 4

What is the key benefit of good architecture regarding teamwork?

Answer 4

Makes it easier for develpers to collaborate

Question 5

What is the key benefit of good architecture regarding testability?

Answer 5

Makes code easier to test

Question 6

What is the key benefit of good architecture regarding technical debt?

Answer 6

Saves time and reduces technical debt as you extend the app

Question 7

Which core design principle separates the UI from the Data Layer?

Answer 7

Separation of concerns.

Question 8

In the MVVM diagram, what component does the Activity or Fragment communicate with directly?

Answer 8

The ViewModel.

Question 9

In the MVVM diagram, where does the Repository fetch data from?

Answer 9

The Model (Local DB) and Remote Data Source (Network).

Question 10

What is the primary responsibility of the ViewModel?

Answer 10

To prepare data for the UI.

And mustn’t reference any UI Component

Question 11

Why must a ViewModel never reference a UI component (like a Widget)?

Answer 11

To avoid memory leaks and decoupling issues.

Question 12

How does a ViewModel handle configuration changes like screen rotation?

Answer 12

It survives the change and retains the data.

Survives as long as the scope is alive

Question 13

What is the primary role of the Repository in app architecture?

Answer 13

To provide a single, clean API for accessing app data.

Question 14

Is the Repository class part of the official Architecture Component libraries?

Answer 14

No, it is a recommended best practice.

Use 2 repository when there is 2 databases

Question 15

What logic does a Repository typically handle regarding data sources?

Answer 15

Deciding whether to fetch new data from the network or use cached local data

Question 16

What is LiveData?

Answer 16

A data holder class that is observable and lifecycle-aware.

Question 17

What happens when LiveData is observed and the data changes?

Answer 17

It notifies the observer (the UI) to update.

Is lifecycle aware

Question 18

Why is LiveData considered ‘lifecycle-aware’?

Answer 18

It respects the lifecycle of other components (like preventing updates when an app is stopped)

Question 19

What is ‘Floor’ in the context of Flutter architecture?

Answer 19

A SQL object mapping library (ORM) that generates SQLite code.

Question 20

What does an ‘Entity’ represent in the Floor library?

Answer 20

It defines the schema of a database table.

Question 21

What does a ‘DAO’ (Database Access Object) define in Floor?

Answer 21

It defines the read and write operations for the database.

Question 22

What does CRUD mean?

Answer 22

1. C - Create
2. R - Retrive
3. U - Update
4. D - Delete

Question 23

In a Floor Entity class, what does a member variable correspond to?

Answer 23

A column name in the database table.

Question 24

On which thread must database operations NOT run?

Answer 24

The main thread

Question 25

How should the FloorDatabase typically be instantiated to manage resources?

Answer 25

As a singleton instance.

Question 26

When passing data from the Database to the UI, what wrapper should be used in all layers?

Answer 26

LiveData.

Question 27

What annotation is used to declare a class as a Floor Database?

Answer 27

@Database

Question 28

What annotation is used to mark a class as a table definition in Floor?

Answer 28

@Entity

Question 29

What can ViewModel represented as in Restaurant?

Answer 29

Waiter

Question 30

What can Repository represented as in Restaurant?

Answer 30

Chef