Terminal operations trigger execution in Kotlin - Mini Project: Build & Apply

Terminal Operations Trigger Execution in Kotlin Sequences

📖 Scenario: You are managing a list of book titles in a library system. You want to filter and process these titles efficiently using Kotlin sequences, which delay execution until a terminal operation is called.

🎯 Goal: Build a Kotlin program that creates a sequence of book titles, configures a filter condition, applies the filter using a sequence operation, and finally triggers execution with a terminal operation.

📋 What You'll Learn

Create a sequence of book titles with exact values

Add a filter condition variable for minimum title length

Use a sequence filter operation with the condition variable

Trigger execution using a terminal operation to collect results

💡 Why This Matters

🌍 Real World

Sequences in Kotlin are used to efficiently process large or infinite data streams by delaying execution until results are needed, saving memory and CPU.

💼 Career

Understanding how terminal operations trigger execution in sequences is important for Kotlin developers working on performance-sensitive applications, such as mobile apps or backend services.

1

Create a sequence of book titles

Create a Kotlin val named bookTitles that is a sequence containing these exact strings in this order: "Kotlin Basics", "Advanced Kotlin", "Database Design", "Android Development", "Coroutines".

Kotlin

# Create a sequence called bookTitles with the given book titles
// Your code here

Need a hint?

Use sequenceOf() to create a sequence with the exact book titles listed.

2

Add a filter condition variable

Create a Kotlin val named minTitleLength and set it to the integer 15. This will be used to filter book titles by length.

Kotlin

val bookTitles = sequenceOf("Kotlin Basics", "Advanced Kotlin", "Database Design", "Android Development", "Coroutines")
// Create a val minTitleLength and set it to 15
// Your code here

Need a hint?

Define minTitleLength as an integer value 15.

3

Apply filter operation on the sequence

Create a Kotlin val named longTitles that filters bookTitles to include only titles whose length is greater than or equal to minTitleLength. Use the filter sequence operation with a lambda that checks it.length >= minTitleLength.

Kotlin

val bookTitles = sequenceOf("Kotlin Basics", "Advanced Kotlin", "Database Design", "Android Development", "Coroutines")
val minTitleLength = 15
// Create a val longTitles by filtering bookTitles with length >= minTitleLength
// Your code here

Need a hint?

Use filter on bookTitles with a lambda checking it.length >= minTitleLength.

4

Trigger execution with a terminal operation

Create a Kotlin val named resultList that collects the filtered sequence longTitles into a list by calling the terminal operation toList().

Kotlin

val bookTitles = sequenceOf("Kotlin Basics", "Advanced Kotlin", "Database Design", "Android Development", "Coroutines")
val minTitleLength = 15
val longTitles = bookTitles.filter { it.length >= minTitleLength }
// Collect longTitles into a list called resultList using toList()
// Your code here

Need a hint?

Call toList() on longTitles to trigger execution and collect results.