Fragmented · January 21, 2019

150: Learning Kotlin - Returns, Jumps & Labels

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Shownotes

Code

data class Customer(val isPlatinum: Boolean)

fun main() {

    val customer = Customer(false)

    println("Number of points customer has: ${calculatePoints(customer)}")

    // Break out of the loop once we're over 25
    for (i in 1..100) {
        if (i > 25) {
            break
        } else {
            println(i)
        }
    }


    // Skip all even numbers
    for (i in 1..100) {
        if (i % 2 == 0) {
            continue
        } else {
            println(i)
        }
    }


    // Break out of the outer loop (which breaks out of the inner too) using a label
    donn@ for (i in 1..100) {
        for (j in 100..200) {
            if (j > 150) break@donn // This will break out of the inner loop and outer loop
            else println("i: $i, j: $j")
        }
    }

    // Continue processing the next outer loop value when a condition is met.
    donn@ for (i in 1..100) {
        for (j in 100..200) {
            if (j > 150) continue@donn // This will break out of the inner loop and outer loop
            else println("i: $i, j: $j")
        }
    }

    // returns with label
    example1()
    example2()

    println("I'm done processing!")
}

fun calculatePoints(customer: Customer): Int {
    if (customer.isPlatinum) {
        return 100000
    } else {
        return 10
    }
}


fun example1() {
    listOf(1, 2, 3, 4, 5, 6, 7, 8, 9).forEach {
        if (it > 7) {
            return
        } else {
            println(it)
        }
    }
    println("This wont print :( because return exited the bar() function")
}

fun example2() {
    listOf(1, 2, 3, 4, 5, 6, 7, 8, 9).forEach bin@ {
        if (it > 7) {
            return@bin
        } else {
            println(it)
        }
    }
    println("This will print! :) return exited the forEach!")
}

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