Kotlin Android Syntax ( for, while, range, when)

Using a for loop

val items = listOf("apple", "banana", "kiwi")

for (item in items)

{

    println(item)

}

or

val items = listOf("apple", "banana", "kiwi")

for (index in items.indices)

{

    println("item at $index is ${items[index]}")

}

Using a while loop

val items = listOf("apple", "banana", "kiwi")

var index = 0

while (index < items.size)

{

    println("item at $index is ${items[index]}")

    index++

}

Using when expression

fun describe(obj: Any): String =

when (obj)

{

    1          -> "One"

    "Hello"    -> "Greeting"

    is Long    -> "Long"

    !is String -> "Not a string"

    else       -> "Unknown"

}

Using ranges

Check if a number is within a range using in operator:

val x = 10

val y = 9

if (x in 1..y+1)

{

    println("fits in range")

}

Check if a number is out of range:

val list = listOf("a", "b", "c")

if (-1 !in 0..list.lastIndex)

{

    println("-1 is out of range")

}

if (list.size !in list.indices)

{

    println("list size is out of valid list indices range too")

}

Iterating over a range:

for (x in 1..5)

{

    print(x)

}

or over a progression:

for (x in 1..10 step 2)

{

    print(x)

}

println()

for (x in 9 downTo 0 step 3)

{

    print(x)

}

Hello Reader

You can comment if any confusion in syntax or if need more explanation we'll reply you ASAP.

Thank you Safe & Happy Coding. :)