Mini Project

Relax. We'll talk through this in plain words — no textbook voice.

In this mini project, we'll bring together the Kotlin basics to build a simple course enrollment summary. You'll get hands-on practice using data classes, lists, functions, filter, map, and string templates all in one place. It's similar to the idea of processing a course list, an enrolled student list, or an active user list in a real app.

kotlin

data class Course(val title: String, val price: Int, val enrolled: Boolean)

fun calculateTotal(courses: List<Course>): Int {
    return courses
        .filter { it.enrolled }
        .map { it.price }
        .sum()
}

fun main() {
    val courses = listOf(
        Course("Kotlin Basics", 30000, true),
        Course("Android UI", 45000, false),
        Course("Backend API", 50000, true)
    )

    val enrolledCourses = courses.filter { it.enrolled }
    val titles = enrolledCourses.map { it.title }
    val total = calculateTotal(courses)

    println("Enrolled courses: $titles")
    println("Total price: $total MMK")
}

You should see

Enrolled courses: [Kotlin Basics, Backend API] Total price: 80000 MMK

Summary

This mini project pulls together the Kotlin fundamentals into a real-world data processing flow.

What's Next

Once you're done with this stage, you can move on to Kotlin coroutines, Android Jetpack Compose, and Spring Boot with Kotlin.

Easy traps

To use sum(), the list items need to be numbers. You can't call sum() directly on a list of Course objects.