I am trying to write function which will tell me that string is nice, nice means string has at least one repetition of letters in the string. But I can't to make return from lambda, it's always return false, though condition in if statement passed. Can somebody explain me how make return?
I have tried to write return, but IDEA gave me the message Kotlin: 'return' is not allowed here
fun main(args: Array<String>) {
println("sddfsdf".isNice())
}
fun String.isNice(): Boolean {
val hasRepeat = {
for (i in 0 .. (length - 2)) {
if (subSequence(i, i + 2).toSet().size == 1) {
true
println(subSequence(i, i + 2))
}
}
false
}
return hasRepeat()
}
ouput is:
dd
false
You can label lambda and then use labeled return:
fun String.isNice(): Boolean {
val hasRepeat = hasRepeat@ {
for (i in 0 .. (length - 2)) {
if (subSequence(i, i + 2).toSet().size == 1) {
return@hasRepeat true
println(subSequence(i, i + 2)) // <-- note that this line is unreachable
}
}
false
}
return hasRepeat()
}
or you can use named local function, if you do not need hasRepeat
to be function reference:
fun String.isNice(): Boolean {
fun hasRepeat(): Boolean {
for (i in 0 .. (length - 2)) {
if (subSequence(i, i + 2).toSet().size == 1) {
return true
}
}
return false
}
return hasRepeat()
}
You cannot do a non-local return inside a lambda but you can change your lambda to an anonymous function:
fun String.isNice(): Boolean {
val hasRepeat = fun(): Boolean {
for (i in 0..(length - 2)) {
if (subSequence(i, i + 2).toSet().size == 1) {
return true
}
}
return false
}
return hasRepeat()
}
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