StateFlow for observable state in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a MutableStateFlow with initial value 0.

Kotlin

val counter = MutableStateFlow([1])

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

Anull

B"0"

C0

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string "0" instead of integer 0

Using null as initial value

Using a boolean false instead of a number

MutableStateFlow requires an initial value of the correct type. Here, 0 is an integer initial value.

2fill in blank

medium

Complete the code to update the StateFlow value by incrementing it by 1.

Kotlin

counter.value = counter.value [1] 1

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A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' which decreases the value

Using '*' or '/' which changes the value differently

To increase the counter by 1, use the plus operator '+'.

3fill in blank

hard

Fix the error in the code to collect StateFlow values in a coroutine.

Kotlin

lifecycleScope.launch {
    counter.[1] { value ->
        println("Counter: $value")
    }
}

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

Aemit

Bcollect

CcollectLatest

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using emit instead of collect

Using value which is not a function

Using collectLatest which is valid but not the simplest here

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

4fill in blank

hard

Fill both blanks to create a StateFlow that only emits even numbers from a MutableStateFlow.

Kotlin

val evenNumbers = counter.[1] { it % 2 == 0 }.[2]()

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Afilter

Bmap

CstateIn

Dcollect

Attempts:

3 left

💡 Hint

Common Mistakes

Using map instead of filter

Using collect which is for terminal operations

Not converting back to StateFlow with stateIn

Use filter to keep only even numbers, then stateIn to convert the flow back to StateFlow.

5fill in blank

hard

Fill all three blanks to create a StateFlow with initial value 0, update it, and collect its values.

Kotlin

val counter = MutableStateFlow([1])

counter.value = counter.value [2] 5

lifecycleScope.launch {
    counter.[3] { value ->
        println("Value: $value")
    }
}

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

A0

B+

Ccollect

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' for updating

Using emit instead of collect

Using wrong initial value

Initialize with 0, add 5 to update, and collect values to observe changes.