StateFlow and SharedFlow in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a StateFlow with an initial value of 0.

Android Kotlin

val _counter = MutableStateFlow([1])
val counter: StateFlow<Int> = _counter

Drag options to blanks, or click blank then click option'

A-1

Bnull

C"0"

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using null as initial value causes errors.

Using a string "0" instead of integer 0.

StateFlow requires an initial value. Here, 0 is the correct integer initial value.

2fill in blank

medium

Complete the code to emit a new value 5 to a MutableSharedFlow.

Android Kotlin

val events = MutableSharedFlow<Int>()
suspend fun sendEvent() {
  events.[1](5)
}

Drag options to blanks, or click blank then click option'

Asubscribe

Bcollect

Cemit

Dlaunch

Attempts:

3 left

💡 Hint

Common Mistakes

Using collect instead of emit.

Trying to call emit outside a suspend function.

To send a value to a SharedFlow, use the emit function inside a suspend function.

3fill in blank

hard

Fix the error in the code to collect values from a StateFlow named stateFlow inside a coroutine.

Android Kotlin

lifecycleScope.launch {
  stateFlow.[1] { value ->
    println(value)
  }
}

Drag options to blanks, or click blank then click option'

Acollect

Bemit

Csend

Dsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Using emit instead of collect.

Trying to collect outside a coroutine.

To receive values from a StateFlow, use the collect function inside a coroutine.

4fill in blank

hard

Fill both blanks to create a SharedFlow that replays the last 3 emitted values and has a buffer capacity of 5.

Android Kotlin

val sharedFlow = MutableSharedFlow<Int>(replay = [1], extraBufferCapacity = [2])

Drag options to blanks, or click blank then click option'

A3

B5

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing replay with buffer capacity.

Setting replay or buffer to zero when not intended.

The replay parameter sets how many past values are replayed to new collectors. extraBufferCapacity sets the buffer size for emitted values.

5fill in blank

hard

Fill all three blanks to create a StateFlow that updates its value and exposes it as an immutable StateFlow.

Android Kotlin

private val _state = MutableStateFlow([1])
val state: StateFlow<Int> = _state.[2]

fun updateValue(newValue: Int) {
  _state.[3] = newValue
}

Drag options to blanks, or click blank then click option'

A0

BasStateFlow()

Cvalue

Demit

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to emit on StateFlow instead of setting value.

Exposing MutableStateFlow directly without asStateFlow.

Initialize MutableStateFlow with 0. Use asStateFlow() to expose immutable StateFlow. Update value by setting value property.