Utilize Control Flow in Kotlin

May 22 2024 · Kotlin 1.9.23, Android 14, Kotlin Playground

Lesson 04: Work with Null Values

Demo

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Open up the starter project to get started.

  val input: String? = args.firstOrNull()

  val input: String = args.firstOrNull()

  val input: String = args.first()

  println("Input length: ${input.length}")

fun main() {
    val args = emptyArray<String>()
    val input: String = args.first()
}

    val nullableNumber = input?.toIntOrNull()
    println("Nullable number of students: $nullableNumber")

    val numberWithElvis = input?.toIntOrNull() ?: 0
    println("Number of students with elvis operator: $numberWithElvis")

    val numberWithCustomException = input?.toIntOrNull()
        ?: throw IllegalArgumentException("Invalid input, please enter a number")
    println("Number of students with custom exception: $numberWithCustomException")

    val nonNullableNumber = input!!.toInt()
    println("Non-nullable number of students: $nonNullableNumber")

    val safeCastNumber = nullableNumber as? Int
    println("Safe cast number: $safeCastNumber")

    val studentsInClassrooms = Arrays.asList(10, 20, null, 25)

  val studentsInClassrooms: MutableList<Int?> = Arrays.asList(10, 20, null, 25)

  val studentsInClassrooms: MutableList<Int> = Arrays.asList(10, 20, null, 25)

    val studentsInClassrooms: MutableList<Int> = Arrays.asList(10, 20, null, 25)
    println("Number of students in the second classroom:")
    println(studentsInClassrooms[1])
    println("Number of students in the third classroom:")
    println(studentsInClassrooms[2])

  val studentsInClassrooms: MutableList<Int?> = Arrays.asList(10, 20, null, 25)

  val studentsInClassrooms = Arrays.asList(10, 20, null, 25)
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