Why Flow matters for async sequences in Kotlin - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple Flow that emits numbers from 1 to 3.

Kotlin

val numbersFlow = flow {
    for (i in 1..[1]) {
        emit(i)
    }
}

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

A10

B3

C0

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a range that is too large or too small.

Forgetting to use the range operator '..'.

The flow emits numbers from 1 to 3, so the upper limit in the range should be 3.

2fill in blank

medium

Complete the code to collect values from the Flow and print them.

Kotlin

runBlocking {
    numbersFlow.[1] { value ->
        println(value)
    }
}

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AflowOn

Blaunch

Cemit

Dcollect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'launch' instead of 'collect' to receive values.

Trying to use 'emit' outside the flow builder.

To receive and process emitted values from a Flow, you use the collect function.

3fill in blank

hard

Fix the error in the code to make the Flow emit values on the IO dispatcher.

Kotlin

val ioFlow = numbersFlow.[1](Dispatchers.IO)

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AflowOn

Bemit

Ccollect

Dlaunch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'collect' or 'launch' instead of 'flowOn'.

Trying to use 'emit' outside the flow builder.

The flowOn operator changes the dispatcher where the upstream flow runs.

4fill in blank

hard

Fill both blanks to create a Flow that emits squares of numbers greater than 2.

Kotlin

val squaresFlow = flow {
    for (num in 1..5) {
        if (num [1] 2) {
            emit(num [2] num)
        }
    }
}

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

A>

B*

C<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the condition.

Using '+' instead of '*' for squaring.

The condition checks if the number is greater than 2, and then emits its square by multiplying the number by itself.

5fill in blank

hard

Fill all three blanks to create a Flow that emits uppercase strings longer than 3 characters.

Kotlin

val words = listOf("cat", "lion", "tiger", "dog")
val filteredFlow = flow {
    for (word in words) {
        if (word.length [1] 3) {
            emit(word.[2]().[3]())
        }
    }
}

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

A>

BtoUpperCase

Cuppercase

DtoLowerCase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for length comparison.

Using 'toLowerCase' instead of uppercase functions.

The condition filters words longer than 3 characters. The uppercase() function converts the string to uppercase. The toUpperCase() is an alternative method call to ensure uppercase conversion.