Functional try & catch with Scala

Question

Is there a more idiomatic way of opening a resource in Scala and applying methods to it than this method (translated directly from java):

var is: FileInputSt         


        

Answer 1

Starting Scala 2.13, the standard library provides a dedicated resource management utility: Using.

It can be used in this case with FileInputStream as it implements AutoCloseable in order to play with an input file and, no matter what, close the file resource afterwards:

import scala.util.{Using, Failure}
import java.io.FileInputStream

Using(new FileInputStream(in)) {
  is => func(is)
}.recoverWith {
  case e: java.io.IOException =>
    println("Error: could not open file.")
    Failure(e)
}

Since Using produces a Try providing either the result of the operation or an error, we can work with the exception via Try#recoverWith.