When to use sequences in Kotlin - Mini Project: Build & Apply

When to use sequences in Kotlin

📖 Scenario: You are working on a Kotlin program that processes a list of numbers. Sometimes the list is small, and sometimes it is very large. You want to learn how to use sequences to handle large data efficiently.

🎯 Goal: Build a Kotlin program that creates a list of numbers, sets a threshold, uses a sequence to filter and map numbers greater than the threshold, and prints the final list.

📋 What You'll Learn

Create a list of integers called numbers with the values 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Create an integer variable called threshold and set it to 5

Use a sequence from numbers to filter numbers greater than threshold and then map each number to its double

Convert the sequence result to a list called result

Print the result list

💡 Why This Matters

🌍 Real World

Sequences help process large or infinite data streams efficiently without creating intermediate collections.

💼 Career

Understanding sequences is useful for Kotlin developers working on performance-sensitive applications or data processing tasks.

1

Create the list of numbers

Create a list of integers called numbers with these exact values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Kotlin

# Create the list of numbers
# Your code here

Need a hint?

Use listOf() to create a list with the given numbers.

2

Set the threshold value

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)
# Create the threshold variable
# Your code here

Need a hint?

Use val threshold = 5 to create the variable.

3

Use a sequence to filter and map

Use a sequence from numbers to filter numbers greater than threshold and then map each number to its double. Store the result as a list in a variable called result

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
val threshold = 5
# Use sequence to filter and map, then convert to list
# Your code here

Need a hint?

Use asSequence() on numbers, then filter and map, finally convert to list with toList().

4

Print the result list

Write a print statement to display the result list

Kotlin

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

Need a hint?

Use println(result) to show the final list.