FIT5046 - Week 8: Network Connection in Android and Retrofit Flashcards

Question 1

What Kotlin delegate keyword is used to defer Retrofit instance creation until it is first accessed?

Accepted Answer

'by lazy' (lazy initialization).

Question 2

What is a Public Web API (Application Programming Interface)?

Accepted Answer

An open interface that provides client applications with access to remote business logic, data, and services over the internet using standard protocols like HTTP.

Question 3

What architectural style forms the foundation of modern Web APIs?

Accepted Answer

Service-Oriented Architecture (SOA) and REpresentational State Transfer (REST) protocols.

Question 4

What data format is most commonly used for sending requests and receiving responses in modern mobile Web APIs?

Accepted Answer

JSON (JavaScript Object Notation).

Question 5

What are the main components of a RESTful HTTP request URL?

Accepted Answer

Scheme (e.g., https), Base URL (domain host), Endpoint path, and Query parameters (key-value pairs).

Question 6

What Android permission must be declared in AndroidManifest.xml to perform network requests?

Accepted Answer

<uses-permission android:name=android.permission.INTERNET />

Question 7

Where inside AndroidManifest.xml must the INTERNET permission tag be placed?

Accepted Answer

Directly inside the root tag, outside of the tag.

Question 8

Why is INTERNET categorized as a normal permission in Android?

Accepted Answer

Because it is granted automatically upon app installation without requiring a runtime permission dialog popup.

Question 9

What happens at runtime if an Android app attempts a network request without the INTERNET permission in the manifest?

Accepted Answer

The system throws a SecurityException or UnknownHostException (Unable to resolve host) and blocks network access.

Question 10

What popular HTTP networking libraries are available for Android development?

Accepted Answer

Retrofit, OkHttp, Volley, Ktor, and native HttpURLConnection.

Question 11

Which networking library is recommended by Google and Monash for Android REST API integration?

Accepted Answer

Retrofit (developed by Square).

Question 12

What underlying HTTP client library powers Retrofit under the hood?

Accepted Answer

OkHttp (also developed by Square).

Question 13

What is the primary role of a Retrofit Converter library like Gson Converter?

Accepted Answer

To automatically parse and convert raw JSON HTTP response bodies into Kotlin data objects and vice versa.

Question 14

Which three Gradle dependencies are required to configure Retrofit with Gson in build.gradle.kts?

Accepted Answer

retrofit core, converter-gson, and the gson library.

Question 15

What is a Retrofit Model class?

Accepted Answer

A Kotlin data class whose property names and types match the JSON keys and data types returned by the REST API.

Question 16

When does a REST API response require a wrapper class vs a direct List<T>?

Accepted Answer

A wrapper class is needed when the root JSON is an object ({}), whereas List<T> is used when the root JSON is an array ([]).

Question 17

What annotation can be used in a Retrofit model if Kotlin field names differ from JSON key names?

Accepted Answer

@SerializedName(json_key_name).

Question 18

What is a Retrofit Interface in Android development?

Accepted Answer

A Kotlin interface annotated with HTTP methods (like @GET) that defines the available API endpoints, request parameters, and return types.

Question 19

What annotation is used in a Retrofit interface to perform HTTP data queries?

Accepted Answer

@GET(endpoint_path).

Question 20

What is the difference between @Query and @Path annotations in a Retrofit interface?

Accepted Answer

@Query appends key-value parameters to the URL query string (?key=value), whereas @Path replaces dynamic placeholder parameters within the URL path ({id}).

Question 21

How do you make a parameter optional in a Retrofit @Query method parameter?

Accepted Answer

By assigning it a nullable type with a default value of null, such as @Query(userId) userId: Int? = null.

Question 22

Why should functions declared inside a Retrofit Interface be marked with the 'suspend' keyword?

Accepted Answer

To allow Retrofit to execute network requests asynchronously within Kotlin coroutines without blocking the main UI thread.

Question 23

What is the role of the RetrofitObject in an Android project architecture?

Accepted Answer

A singleton object declaration that creates and configures the shared Retrofit client instance.

Question 24

Why is Kotlin's 'object' keyword used instead of a 'class' when defining RetrofitObject?

Accepted Answer

Because 'object' inherently enforces the Singleton pattern in Kotlin, ensuring only one instance of the Retrofit service exists.

Question 25

Why is lazy initialization ('by lazy') recommended for building the Retrofit instance?

Accepted Answer

To avoid unnecessary computation and resource usage during app startup until a network call is actually made.

FIT5046 - Week 8: Network Connection in Android and Retrofit

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