在 Kotlin 中生成随机字母数字字符串的惯用方法

发布于10月26日

I can generate a random sequence of numbers in a certain range like the following:

fun ClosedRange<Int>.random() = Random().nextInt(endInclusive - start) +  start
fun generateRandomNumberList(len: Int, low: Int = 0, high: Int = 255): List<Int> {
  (0..len-1).map {
    (low..high).random()
  }.toList()
}

然后我必须用以下方法延长List次:

fun List<Char>.random() = this[Random().nextInt(this.size)]

然后我可以做:

fun generateRandomString(len: Int = 15): String{
  val alphanumerics = CharArray(26) { it -> (it + 97).toChar() }.toSet()
      .union(CharArray(9) { it -> (it + 48).toChar() }.toSet())
  return (0..len-1).map {
      alphanumerics.toList().random()
  }.joinToString("")
}

但也许有更好的办法？

推荐答案

Assuming you have a specific set of source characters (source in this snippet), you could do this:

val source = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
java.util.Random().ints(outputStrLength, 0, source.length)
        .asSequence()
        .map(source::get)
        .joinToString("")

Which gives strings like "LYANFGNPNI" for outputStrLength = 10.

两个重要的位是