Java streams vs Kotlin sequences - Hands-On Comparison

Java Streams vs Kotlin Sequences

📖 Scenario: You are working on a Kotlin program that processes a list of numbers. You want to compare how Java streams and Kotlin sequences handle data processing step-by-step.

🎯 Goal: Build a Kotlin program that creates a list of numbers, sets a threshold, filters numbers greater than the threshold using a Kotlin sequence, and prints the filtered list. This will help you understand the difference between Java streams and Kotlin sequences.

📋 What You'll Learn

Create a list of integers with exact values

Create a threshold variable

Use a Kotlin sequence to filter numbers greater than the threshold

Print the filtered list

💡 Why This Matters

🌍 Real World

Processing large data collections efficiently is common in apps like data analysis, filtering user inputs, or handling streams of events.

💼 Career

Understanding Kotlin sequences and Java streams is valuable for developers working with Kotlin or Java, especially in backend or Android development where data processing is frequent.

1

Create the initial list of numbers

Create a list called numbers with these exact integers: 5, 10, 15, 20, 25

Kotlin

# Create a list called numbers with 5, 10, 15, 20, 25
# Your code here

Need a hint?

Use listOf() to create the list with the exact numbers.

2

Set the threshold value

Create an integer variable called threshold and set it to 12

Kotlin

val numbers = listOf(5, 10, 15, 20, 25)
# Create an integer variable called threshold and set it to 12
# Your code here

Need a hint?

Use val threshold = 12 to create the variable.

3

Filter numbers greater than threshold using a Kotlin sequence

Create a variable called filteredNumbers that uses numbers.asSequence() and filter to keep numbers greater than threshold, then convert it back to a list with toList()

Kotlin

val numbers = listOf(5, 10, 15, 20, 25)
val threshold = 12
# Create filteredNumbers using numbers.asSequence(), filter, and toList()
# Your code here

Need a hint?

Use asSequence() to start the sequence, then filter { it > threshold }, and finally toList() to get the result.

4

Print the filtered list

Write a println statement to display the filteredNumbers list

Kotlin

val numbers = listOf(5, 10, 15, 20, 25)
val threshold = 12
val filteredNumbers = numbers.asSequence().filter { it > threshold }.toList()
# Print filteredNumbers
# Your code here

Need a hint?

Use println(filteredNumbers) to show the filtered list.