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Kotlin Starter Pack

romainbsl
13.4K 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 ...

// {...}
val numbers = listOf(1, 2, 3)
// {...}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Set of ...

// {...}
val numbers = setOf(1, 2, 2, 3, 4, 3)
// {...}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Map to ...

// {...}
val map = hashMapOf(1 to "first", 2 to "second", 3 to "third")
// {...}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

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.

// {...}
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.
// {...}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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