heejin's blog

Kotlin Collections: map, filter, reduce and More

Kotlin
collections
Last modified: 
2026-03-8
A practical Kotlin collections cheat sheet for Android developers. Learn how to use map, filter, reduce, groupBy, and other essential collection functions with examples.

Kotlin Null Safety Explained: ?, !!, let and Safe Calls

Kotlin
Null safety
Last modified: 
2026-03-6
Learn Kotlin null safety with practical examples. Understand safe calls (?.), the not-null assertion (!!), let, and best practices for avoiding NullPointerException in Android development.

Kotlin Scope Functions Explained: let vs run vs apply vs also vs with (Android Developer Cheat Sheet)

cheat sheet
Last modified: 
2026-03-5
A practical Kotlin scope functions guide for Android developers. Learn the difference between let , run , apply , also , and with with examples, comparison tables, and practical developer tips.

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