Summary - Arrays

Combine arrayOf, size and map to write a class list.

Summary - Arrays

In this summary you'll combine arrayOf, size and map to build a class list app. In previous lessons you learned:

creating arrays with arrayOf and intArrayOf
accessing elements with arr[i]
size, indices, lastIndex
iterating with for
map, filter, forEach

We'll do two mini tasks: add 10 points to grades (map) and filter passing grades (filter).

Exercise Add 10 points to grades

Write a fun main(). Create a grades array with val grades = intArrayOf(50, 70, 90). Add 10 to each grade with val bonus = grades.map { it + 10 }. Print the result with println(bonus).

Show example solution

fun main() {
    val grades = intArrayOf(50, 70, 90)
    val bonus = grades.map { it + 10 }
    println(bonus)
}

Exercise Filter passing grades

Write a fun main(). Create a grades array with val grades = intArrayOf(50, 30, 70, 20). Filter passing grades (50 and above) with val passing = grades.filter { it >= 50 }. Print the result with println(passing).

Show example solution

fun main() {
    val grades = intArrayOf(50, 30, 70, 20)
    val passing = grades.filter { it >= 50 }
    println(passing)
}

Test yourself

Which method transforms each element of an array?
- map
- forEach
- filter
- size
Show answer

map — map transforms each element.

Complete the map call

val bonus = grades.____ { it + 10 }

Show answer

val bonus = grades.map { it + 10 }

Next lesson: Creating lists

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies