3.5. Control-flow statements
3.5.1. Conditional statements
Kotlin provides the typical if...else
conditional statement available in all programming languages. Moreover, we also have the statement when
, a multi-branch conditional statement with multiple branches, similar to the switch...case
of other languages:
var input:String = "help"
when (input) {
"help" -> {
Log.i("info","help text")
}
"exec" -> {
Log.i("info","exec text")
}
else -> {
print("command error")
}
}
3.5.2. Loop statements
Kotlin offers the classic while
loop statement, which executes a sequence of statements while a condition is met:
Factorial var = 1;
while (i > 1) {
factorial *= i
i--
}
If we want to traverse all the elements of a data structure, it is preferable to use a for
loop:
val arrayList = ArrayList<String>()
arrayList.add("Hello")
arrayList.add("Bye")
for (item: String in arrayList) {
Log.i("info",item)
}
We can also traverse a numerical range using the following syntax:
for (i in 1..10) {
}
It is also possible to define more complex traversals, such as traversing a range in reverse (downTo
) skipping two values at a time (step 2
):
for (i in 10 downTo 0 step 2) {
Log.i("info",i.toString())
}
Finally, we can exit a loop by using a break
statement. If this is necessary, then it is preferable to use a while
loop instead.