Programming in Kotlin: Fundamentals

Aug 9 2022 · Kotlin 1.6, Android 12, IntelliJ IDEA CE 2022.1.3

Part 2: Manage Control Flow

16. Simplify Code with When Expressions

Episode complete

Play next episode

Next
About this episode

Leave a rating/review

See forum comments
Cinema mode Mark complete Download course materials
Previous episode: 15. Learn more Loop Features Next episode: 17. Challenge: Use When Expressions

Get immediate access to this and 4,000+ other videos and books.

Take your career further with a Kodeco Personal Plan. With unlimited access to over 40+ books and 4,000+ professional videos in a single subscription, it's simply the best investment you can make in your development career.

Learn more Already a subscriber? Sign in.

Heads up... You've reached locked video content where the transcript will be shown as obfuscated text.

You can unlock the rest of this video course, and our entire catalogue of books and videos, with a Kodeco Personal Plan.

Unlock now

You learned how If/Else expressions are also a part of managing the control flow. Sometimes you have a lot of cases in such an expression, and the logic gets complicated, or just too long to cover with just if/else statements.

val age = 23

when(age) {

}

when(age) {
 23 -> println("Close to a quarter century!")
 25 -> println("Quarter century!")
 else -> {
   println("Don't know your age!")
 }
}

when(age) {
  in 0..12 -> println("Still a young human")
  in 13..19 -> println("Teenager")
  in 20..29 -> println("In your twenties")
  in 30..39 -> println("In your thirties")
  in 40..49 -> println("In your forties")
  else -> println("You're a wise person :]")
}

val message = when(age) {
  in 0..12 -> "Still a young human"
  in 13..19 -> "Teenager"
  in 20..29 -> "In your twenties"
  in 30..39 -> "In your thirties"
  in 40..49 -> "In your forties"
  else -> "You're a wise person :]"
}

println(message)

val email = "mail@mail.com"
val password = "iLoveKotlin!"

when {
}

when {
  email.isEmpty() -> {
    println("You need to choose an email!")
  }
}

when {
  ...
  
  "@" !in email -> {
    println("Your email is invalid :[")
  }
}

when {
  ...
  
  password.isEmpty() -> {
    println("You need to choose a password!")
  }

  password.length < 10 -> {
    println("Password not strong enough :[")
  }
}

when {
  ...
  
  else -> {
   println("Email length: ${email.length}, " +
      "Password length: ${password.length}")
  }
}

when {
  email.isEmpty() -> println("You need to choose an email!")

  "@" !in email -> println("Your email is invalid :[")

  password.isEmpty() -> println("You need to choose a password!")

  password.length < 10 -> println("Password not strong enough :[")

  else -> println("Email length: ${email.length}, " +
  "Password length: ${password.length}")
}