A Scala Try, Success, and Failure example

By Alvin Alexander. Last updated: September 29, 2022

Without much introduction or discussion, here’s an example of how to use Scala’s Try, Success, and Failure classes:

package com.devdaily.sarah.tests

import scala.util.{Try, Success, Failure}
import java.io._

object TrySuccessFailure extends App {

    badAdder(3) match {
        case Success(i) => println(s"success, i = $i")
        case Failure(t) =>
            println(s"CLASS = ${t.getClass}")

            // this works, but it's not too useful/readable
            //println(t.getStackTrace.mkString("\n"))

            // this works much better
            val sw = new StringWriter
            t.printStackTrace(new PrintWriter(sw))
            println(sw.toString)
    }
   
    /**
     * This method returns a `Success[Int]` if everything goes well,
     * otherwise it throws an exception wrapped in a `Failure`.
     */
    def badAdder(a: Int): Try[Int] = {
        Try({
            val b = a + 1
            if (b == 3) b else {
                val ioe = new IOException("Boom!")
                throw new AlsException("Bummer!", ioe)
            }
        })
    }
   
    class AlsException(s: String, e: Exception) extends Exception(s: String, e: Exception)
}

I created this example to test how Try/Success/Failure would work with a block of code that returns an Int or throws and Exception.