Flow context preservation in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple flow emitting numbers 1 to 3.

Kotlin

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

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Ai

B3

Cflow

Dcollect

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed number like 3 instead of the loop variable.

Trying to emit the flow itself instead of a value.

The emit function sends each value from the flow. Here, i is the current number in the loop.

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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Aemit

BflowOn

Claunch

Dcollect

Attempts:

3 left

💡 Hint

Common Mistakes

Using emit instead of collect.

Trying to launch the flow instead of collecting.

The collect function gathers the emitted values from the flow and lets you process them.

3fill in blank

hard

Fix the error in the code to switch the flow context to Dispatchers.IO.

Kotlin

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

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AflowOn

Bcollect

Claunch

Demit

Attempts:

3 left

💡 Hint

Common Mistakes

Using collect or emit which do not change context.

Trying to launch the flow instead of switching context.

The flowOn operator changes the context where the flow runs, here to Dispatchers.IO.

4fill in blank

hard

Fill both blanks to create a flow that emits squares of numbers only if they are even.

Kotlin

val evenSquares = flow {
    for (x in 1..5) {
        if (x [1] 2 == 0) {
            emit(x [2] x)
        }
    }
}

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A%

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of multiplication for square.

Using wrong operator for checking even numbers.

The modulo operator % checks if a number is even. The multiplication operator * calculates the square.

5fill in blank

hard

Fill all three blanks to create a flow that emits uppercase strings only if their length is greater than 3.

Kotlin

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

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Alength

BtoUpperCase

CflowOn

DtoLowerCase

Attempts:

3 left

💡 Hint

Common Mistakes

Using toLowerCase() instead of toUpperCase().

Forgetting to switch the flow context with flowOn.

Using parentheses incorrectly on properties.

length gets the string length, toUpperCase() converts to uppercase, and flowOn changes the flow context.