Flow builder and collect in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Kotlin

val numberFlow = flow {
    emit([1])
    emit(2)
    emit(3)
}

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

A0

B5

C4

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of 1 as the first emitted value.

Using a number outside the range 1 to 3.

The emit function sends values to the flow. Here, the first emitted value should be 1.

2fill in blank

medium

Complete the code to collect and print each value from the flow.

Kotlin

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

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

Aemit

Blaunch

Ccollect

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'emit' instead of 'collect'.

Using 'launch' which starts a coroutine but does not collect flow values.

The collect function is used to receive and process each value emitted by the flow.

3fill in blank

hard

Fix the error in the flow builder by completing the code to emit squares of numbers from 1 to 3.

Kotlin

val squareFlow = flow {
    for (i in 1..3) {
        emit(i [1] i)
    }
}

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication.

Using division or subtraction which do not calculate squares.

The multiplication operator * is used to calculate the square of each number.

4fill in blank

hard

Fill both blanks to create a flow that emits even numbers from 1 to 6.

Kotlin

val evenFlow = flow {
    for (num in 1..6) {
        if (num [1] 2 == 0) {
            emit(num[2]0)
        }
    }
}

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

A%

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication or subtraction in the condition instead of modulo.

Modifying the number when emitting instead of emitting it as is.

The modulo operator % checks if a number is even by seeing if the remainder when divided by 2 is zero. The plus operator + is used here to emit the number as is (no change).

5fill in blank

hard

Fill all three blanks to create a flow that emits uppercase strings from a list and collects them.

Kotlin

val words = listOf("apple", "banana", "cherry")

val upperFlow = flow {
    for (word in words) {
        emit(word[1])
    }
}

runBlocking {
    upperFlow.[2] { value ->
        println(value[3])
    }
}

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

A.uppercase()

Bcollect

C.toUpperCase()

D.lowercase()

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase conversion instead of uppercase.

Using 'emit' instead of 'collect' to gather values.

.uppercase() converts strings to uppercase in Kotlin 1.5+. The collect function gathers emitted values. .toUpperCase() is a valid method to print the string in uppercase (older style).