A generic method that can return a random integer between 2 parameters like ruby does with rand(0..n)
.
Any suggestion?
As of 1.3, the standard library provided multi-platform support for randoms, see this answer.
If you are working with Kotlin JavaScript and don't have access to java.util.Random
, the following will work:
fun IntRange.random() = (Math.random() * ((endInclusive + 1) - start) + start).toInt()
Used like this:
// will return an `Int` between 0 and 10 (incl.)
(0..10).random()
Building off of @s1m0nw1 excellent answer I made the following changes.
Code:
private object RandomRangeSingleton : Random()
fun ClosedRange<Int>.random() = RandomRangeSingleton.nextInt((endInclusive + 1) - start) + start
Test Case:
fun testRandom() {
Assert.assertTrue(
(0..1000).all {
(0..5).contains((0..5).random())
}
)
Assert.assertTrue(
(0..1000).all {
(0..4).contains((0 until 5).random())
}
)
Assert.assertFalse(
(0..1000).all {
(0..4).contains((0..5).random())
}
)
}
To get a random Int number in Kotlin use the following method:
import java.util.concurrent.ThreadLocalRandom
fun randomInt(rangeFirstNum:Int, rangeLastNum:Int) {
val randomInteger = ThreadLocalRandom.current().nextInt(rangeFirstNum,rangeLastNum)
println(randomInteger)
}
fun main() {
randomInt(1,10)
}
// Result – random Int numbers from 1 to 9
Hope this helps.
to be super duper ))
fun rnd_int(min: Int, max: Int): Int {
var max = max
max -= min
return (Math.random() * ++max).toInt() + min
}
Another way of implementing s1m0nw1's answer would be to access it through a variable. Not that its any more efficient but it saves you from having to type ().
val ClosedRange<Int>.random: Int
get() = Random().nextInt((endInclusive + 1) - start) + start
And now it can be accessed as such
(1..10).random
No need to use custom extension functions anymore. IntRange has a random() extension function out-of-the-box now.
val randomNumber = (0..10).random()