I have two strings
val a = "abc"
val b = "xyz"
I want to merge it and need output like below
axbycz
I added both strings to arraylist and then flatmap it
val c = listOf(a, b)
val d = c.flatMap {
it.toList()
}
but not getting the desired result
Use the zip function. It creates a list of pairs with "adjacent" letters. You can then use joinToString with a transformer to create your final result.
a.zip(b) // Returns the list [(a, x), (b, y), (c, z)]
.joinToString("") { (a, b) -> "$a$b" } // Joins the list back to a string with no separator
You can always use a simple loop, assuming both strings have the same size. That way You only allocate a StringBuilder and counter variable, without any lists, arrays or pairs:
val a = "abc"
val b = "xyz"
val sb = StringBuilder()
for(i in 0 until a.length){
sb.append(a[i]).append(b[i])
}
val d = sb.toString()
marstran's answer is really concise and Pawels answer is really fast. Using buildString you can have to best of both worlds:
buildString {
a.zip(b).forEach { (a, b) ->
append(a).append(b)
}
}
buildString creates a StringBuilder and offers it as receiver in the lambda. It returns the built string.
Try it out here: Kotlin Playground. Thanks to Pawel for creating the original benchmark.