How to replace the first occurrence of a substring in a string with Scala

1 Answer

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object ReplaceFirstApp {
  def replaceFirst(input: String, search: String, replace: String): String = {
    val index = input.indexOf(search)
    if (index >= 0) {
      val before = input.substring(0, index)
      val after = input.substring(index + search.length)
      before + replace + after
    } else {
      input
    }
  }

  def main(args: Array[String]): Unit = {
    val s = "aa bb cc dd ee cc"
    
    val result = replaceFirst(s, "cc", "YY")
    println(result)
  }
}


 
 
/*
run:
 
aa bb YY dd ee cc
 
*/

 



answered Jul 20, 2025 by avibootz
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