Sequence vs collection performance in Kotlin - Hands-On Comparison

Sequence vs Collection Performance in Kotlin

📖 Scenario: You are working on a Kotlin program that processes a list of numbers. You want to understand how using Sequence compares to using a regular List in terms of performance when filtering and mapping data.

🎯 Goal: Build a Kotlin program that creates a list of numbers, sets up a threshold value, applies filtering and mapping using both List and Sequence, and completes the code to compare their usage.

📋 What You'll Learn

Create a List of integers from 1 to 10

Create a threshold variable called threshold with value 5

Use filter and map on the List to get numbers greater than threshold and multiply them by 2

Use asSequence() on the List and apply the same filter and map operations

Convert the Sequence back to a List to complete the processing

💡 Why This Matters

🌍 Real World

Processing large collections of data efficiently is common in apps, and sequences help by doing operations lazily.

💼 Career

Understanding sequences vs collections is important for Kotlin developers to write efficient and clean code.

1

Create the initial list of numbers

Create a List called numbers containing the integers from 1 to 10.

Kotlin

# Your code here

Need a hint?

Use listOf to create a list with the exact numbers 1 through 10.

2

Add a threshold variable

Create an integer variable called threshold and set it to 5.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
# Your code here

Need a hint?

Just create a variable named threshold and assign it the value 5.

3

Filter and map the list

Create a new List called filteredMappedList by filtering numbers to keep only values greater than threshold and then mapping each remaining number to its double (multiply by 2).

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
val threshold = 5
# Your code here

Need a hint?

Use filter with a lambda checking it > threshold, then map to multiply by 2.

4

Use Sequence to filter and map

Create a new List called filteredMappedSequence by converting numbers to a Sequence using asSequence(), then applying the same filter and map operations, and finally converting the result back to a List.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
val threshold = 5
val filteredMappedList = numbers.filter { it > threshold }.map { it * 2 }
# Your code here

Need a hint?

Use asSequence() on numbers, then filter and map, and finally toList().