Truncating Strings by Bytes

Question

I create the following for truncating a string in java to a new string with a given number of bytes.

        String truncatedValue = \"\";
        String curren         


        

Answer 1

Binary search approach in scala:

private def bytes(s: String) = s.getBytes("UTF-8")

def truncateToByteLength(string: String, length: Int): String =
  if (length <= 0 || string.isEmpty) ""
  else {
    @tailrec
    def loop(badLen: Int, goodLen: Int, good: String): String = {
      assert(badLen > goodLen, s"""badLen is $badLen but goodLen is $goodLen ("$good")""")
      if (badLen == goodLen + 1) good
      else {
        val mid = goodLen + (badLen - goodLen) / 2
        val midStr = string.take(mid)
        if (bytes(midStr).length > length)
          loop(mid, goodLen, good)
        else
          loop(badLen, mid, midStr)
      }
    }

    loop(string.length * 2, 0, "")
  }