Kotlin Starter Pack
romainbsl
46.8K views
Collections
It's important to understand that Kotlin's collection are built on top of the Java API. That means a lot for interoperability.
But, Kotlin brings consistency and simplicity.
List of ...
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// {
fun main(args: Array<String>) {
//}
val numbers = listOf(1, 2, 3)
// {
numbers.forEach { println(it) }
}
//}
Set of ...
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// {
fun main(args: Array<String>) {
//}
val numbers = setOf(1, 2, 2, 3, 4, 3)
// {
numbers.forEach { println(it) }
}
//}
Map to ...
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// {
fun main(args: Array<String>) {
//}
val map = hashMapOf(1 to "first", 2 to "second", 3 to "third")
// {
map.forEach {(key, value) -> println("key: $key ; value: $value")}
}
//}
Note that beyond that simplicity, Kotlin provides some cool features, essentially based on extensions of the Java API.
Here a sample of what Kotlin is capable of. You may find more into the Kotlin documentation.
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// {
fun main(args: Array<String>) {
//}
val numbers = listOf(1, 2, 3)
// forearch with indexes
numbers.forEachIndexed { index, it -> println("At index $index there is $it") }
// first()
println("numbers' first is: ${numbers.first()}")
// last
println("numbers' last is: ${numbers.last()}")
// sum
println("numbers' sum is: ${numbers.sum()}")
// etc.
// {
}
//}
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