Compose ViewModel Quiz

This set of multiple-choice questions focuses on the role of the ViewModel in Android architecture, particularly in conjunction with Jetpack Compose. It explores key concepts such as state management, lifecycle handling, separation of concerns, and the use of functions like viewModel() and observeAsState() for integrating ViewModel data into Composable functions. By understanding these concepts, developers can effectively manage UI-related data, maintain consistency across configuration changes, and ensure clean separation between UI logic and data handling in their Android applications.

Which architecture component is still relevant in modern Android app development with Compose?

Activity Navigation

LiveData

ViewModel

DataBinding

None

How does the ViewModel help with activity lifecycle management?

It prevents activities from being destroyed

It ensures that data is persisted even when an activity is recreated

It directly handles activity recreation

It controls the lifecycle of fragments

None

How is a MutableState in Compose different from MutableLiveData?

MutableLiveData can only be used with Compose

MutableState persists data across configuration changes automatically

MutableState is specific to Compose and used for state management within Composables

MutableState can store complex data types like JSON directly

None

Which function is used to create or access a ViewModel instance in a Composable?

rememberViewModel()

createViewModel()

getViewModel()

viewModel()

None

How does a ViewModel instance behave when an activity is recreated?

It is stored in the device’s local database

It persists, maintaining the state data

It automatically stores data to shared preferences

It is destroyed and recreated with the activity

None

What is the primary purpose of the ViewModel component in Android architecture?

To manage user interface elements directly

To handle database interactions

To store and manage UI-related data separately from UI logic

To design the layout of an Android app

None

When using a ViewModel with Compose, where is the best place to initialize the ViewModel?

At the root level of the Composable hierarchy

Inside a coroutine function

In the MainActivity’s onCreate method

Inside a child Composable function

None

What is the purpose of the observeAsState() function?

To convert LiveData into a Compose state object

To manage the lifecycle of an activity

To create a new ViewModel

To update the UI without recomposition

None

What dependency must be added to use the Compose viewModel() function?

androidx.activity:activity-compose

androidx.lifecycle:lifecycle-viewmodel-compose

androidx.compose.runtime:runtime-livedata

androidx.compose.ui:ui

None

10.

Which of the following statements is true about the viewModel() function?

It creates a new ViewModel instance every time

It requires a unique key to be used

It cannot be used with navigation components

It shares a ViewModel instance with all Composables in the same scope

None

11.

Which statement about MutableLiveData is correct?

It allows observing data changes within a ViewModel

It is exclusive to the Compose framework

It can be used to store large files in memory

It is used to observe UI elements in real-time

None

12.

What is the primary benefit of using LiveData with ViewModel in a non-Compose Android app?

LiveData replaces the need for data binding

LiveData is faster than using state variables

LiveData automatically updates the UI when data changes

LiveData can only be used with ViewModel

None

13.

When should you use the MutableLiveData class in a ViewModel?

When you need to handle user input events directly

When you want to store observable data that predates Compose

When you want to observe changes in data using Compose state

When you need to implement animations

None

14.

What is a common use case for the viewModelScope in a ViewModel?

Defining UI layouts

Handling user input directly

Performing network calls or database operations

Managing UI navigation

None

15.

What role does the MutableState object play in a ViewModel with Compose?

It stores the layout design

It manages background tasks

It handles error logging

It holds the current state value that triggers UI recompositions

None

16.

Which of the following is true about the viewModel() function?

It handles network requests

It returns an existing ViewModel instance if one is already created

It can be used to observe changes in data directly

It always creates a new instance of a ViewModel

None

17.

Which Compose library function converts a LiveData object into a State object?

stateObserver()

stateFromLiveData()

liveDataToState()

observeAsState()

None

18.

What is the key benefit of using ViewModel with a Compose UI?

It directly controls the UI layout

It speeds up UI rendering

It enables direct interaction with Android services

It helps maintain data consistency during configuration changes

None

19.

Which of the following is a key principle of modern Android architecture recommended by Google?

Single activity apps with separated responsibilities

Multiple activity-based apps with mixed UI and data logic

Using only fragments for UI management

Apps with no separation between UI and data logic

None

20.

Why is it important to use viewModelScope when performing background tasks?

It manages lifecycle of UI components

It keeps the ViewModel active after the activity is destroyed

It automatically cancels tasks when the ViewModel is cleared

It enhances the speed of recomposition

None

21.

What role does the 'separation of concerns' concept play in Android app architecture?

It combines multiple activities into one

It focuses on integrating third-party libraries

It separates different areas of functionality into distinct modules

It merges UI logic with data handling in a single module

None

22.

Why is it recommended to initialize a ViewModel in a top-level Composable?

To avoid creating multiple instances of the ViewModel

To minimize the number of Composables in an app

To allow child Composables to access and observe the state easily

To ensure that the UI and data are tightly coupled

None

23.

Which of the following best describes 'separation of concerns' in Android architecture?

Storing all data in the ViewModel

Dividing different responsibilities into separate modules

Combining UI code and backend logic

Keeping all code in a single activity class

None

24.

In a ViewModel, what triggers the recomposition of the UI?

Using the viewModel() function

Launching a new activity

Initialization of the ViewModel

Changes to the ViewModel state data

None

Time’s up

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