Get random number between two numbers in Scala

Question

How do I get a random number between two numbers say 20 to 30?

I tried:

val r = new scala.util.Random
r.nextInt(30)

This allows only upper bound value, but values always starts with 0. Is there a way to set lower bound value (to 20 in the example)?

Thanks!

Answer 1

You can use below. Both start and end will be inclusive.

val start = 20
val end   = 30
val rnd = new scala.util.Random
start + rnd.nextInt( (end - start) + 1 )  

In your case

val r = new scala.util.Random
val r1 = 20 + r.nextInt(( 30 - 20) + 1)

Answer 2

Sure. Just do

20 + r. nextInt(10)

Answer 3

Starting Scala 2.13 , scala.util.Random provides:

def between(minInclusive: Int, maxExclusive: Int): Int

which used as follow, generates an Int between 20 (included) and 30 (excluded):

import scala.util.Random
Random.between(20, 30) // in [20, 30[

Answer 4

同时将math.random值（范围在0到1之间）缩放到感兴趣的区间，并将Double在这种情况下转换为Int ，例如

(math.random * (30-20) + 20).toInt

Answer 5

You can use java.util.concurrent.ThreadLocalRandom as an option. It's preferable in multithreaded environments.

val random: ThreadLocalRandom = ThreadLocalRandom.current()
val r = random.nextLong(20, 30 + 1) // returns value between 20 and 30 inclusively

Answer 6

I would recommend using Random.between(a, b)
Note that a in inclusive, and b is exclusive.
Refer to documentation here .

  val r = new scala.util.Random

  // get 10 random numbers between 20 and 30 inclusive
  (1 to 10).foreach(x => println(r.between(20, 30+1)))

Output

28
26
29
30
22
29
28
22
20
24

Process finished with exit code 0