Why ViewModel survives configuration changes in Android Kotlin - Quick Recap

Recall & Review

beginner

What is a ViewModel in Android?

A ViewModel is a class designed to store and manage UI-related data in a lifecycle conscious way. It helps data survive configuration changes like screen rotations.

beginner

How does ViewModel survive configuration changes?

ViewModel objects are tied to the lifecycle of an activity or fragment but are retained when those components are recreated during configuration changes, so data is preserved.

intermediate

What role does ViewModelStore play in ViewModel survival?

ViewModelStore holds ViewModel instances and is retained by the system during configuration changes, allowing ViewModels to persist across activity or fragment recreation.

intermediate

Why is it better to use ViewModel instead of onSaveInstanceState for data persistence?

ViewModel can hold complex data and live longer during configuration changes without serialization, unlike onSaveInstanceState which only saves small amounts of serializable data.

beginner

What happens to a ViewModel when the activity is finished or destroyed permanently?

When the activity or fragment is finished and not recreated, the ViewModel is cleared and its resources are released to avoid memory leaks.

What allows a ViewModel to survive configuration changes?

A It is stored in ViewModelStore which is retained by the system

B It saves data to a file automatically

C It uses onSaveInstanceState internally

D It recreates data every time the activity restarts

ViewModelStore keeps ViewModels alive during configuration changes, so data is preserved.

When does the ViewModel get cleared?

A When the user presses the back button once

B When the activity is recreated due to rotation

C When the app goes to background

D When the activity is finished permanently

ViewModel is cleared only when the activity or fragment is finished and not recreated.

Which of these is NOT a benefit of using ViewModel?

A Survives configuration changes

B Automatically saves data to disk

C Manages UI-related data lifecycle

D Prevents memory leaks by clearing data

ViewModel does not save data to disk automatically; it holds data in memory.

What is a configuration change in Android?

A Screen rotation or language change

B Changing app theme

C Installing a new app

D Updating Android OS

Configuration changes include screen rotations or language changes that recreate activities.

Why is ViewModel preferred over onSaveInstanceState for large data?

A Because ViewModel saves data to a database

B Because onSaveInstanceState is deprecated

C Because onSaveInstanceState can only save small serializable data

D Because ViewModel runs on a background thread

onSaveInstanceState is limited to small serializable data; ViewModel can hold larger and complex data in memory.

Explain in your own words why ViewModel survives configuration changes in Android.

Think about what happens when the screen rotates and how ViewModel keeps data safe.

Describe the difference between ViewModel and onSaveInstanceState for handling data during configuration changes.

Consider how each method stores data and when it is restored.