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RetrieveSingleElement.kt
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RetrieveSingleElement.kt
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// ref : https://kotlinlang.org/docs/collection-elements.html
fun main() {
}
fun getElementFromSetSampleCode() {
val numbers = linkedSetOf("one", "two", "three", "four", "five")
println(numbers.elementAt(3))
val numbersSortedSet = sortedSetOf("one", "two", "three", "four")
println(numbersSortedSet.elementAt(0)) // elements are stored in the ascending order
}
fun getElementFromListSampleCode() {
val numbers = listOf("one", "two", "three", "four", "five")
println(numbers[0])
println(numbers.get(0))
println(numbers.elementAt(0))
println(numbers.first())
println(numbers.last())
println(numbers.elementAt(20)) // runtime error
println(numbers.elementAtOrNull(20))
println(numbers.elementAtOrElse(20, { index -> "The value for index $index is undefined"}))
}
fun firstLastSampleCode() {
val numbers = listOf("one", "two", "three", "four", "five", "six")
println(numbers.first { it.length > 3 })
println(numbers.last { it.startsWith("f") })
}
fun firstLastNullCheckSampleCode() {
val numbers = listOf("one", "two", "three", "four", "five", "six")
println(numbers.firstOrNull { it.length > 6 })
}
fun findSampleCode() {
val numbers = listOf(1, 2, 3, 4)
println(numbers.find { it % 2 == 0 }) // ( == firstOrNull )
println(numbers.findLast { it % 2 == 0 }) // ( == lastOrNull )
}
fun checkRandomOperatorCode() {
val numbers = listOf(1, 2, 3, 4)
println(numbers.random())
println(numbers.randomOrNull())
}
fun checkExistenceSampleCode() {
val numbers = listOf("one", "two", "three", "four", "five", "six")
println(numbers.contains("four"))
println("zero" in numbers)
println(numbers.containsAll(listOf("four", "two")))
println(numbers.containsAll(listOf("one", "zero")))
}
fun isEmptySampleCode() {
val numbers = listOf("one", "two", "three", "four", "five", "six")
println(numbers.isEmpty())
println(numbers.isNotEmpty())
val empty = emptyList<String>()
println(empty.isEmpty())
println(empty.isNotEmpty())
}