[Android Kotlin 기초] 4-1. Start an external Activity
[Android Kotlin 기초] 3-4. Data binding basics
[Android Kotlin 기초] 3-3. 소개.컨스트레이아웃
[Android Kotlin 기초] 3-3. ConstraintLayout using the Layout Editor
[Android Kotlin 기초] 3-2. Add user interactivity