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Why use Try instead of Scala Try Catch

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Scala try catch is always an option when writing Scala code for Java like exception control flows.
However, you also have the option of start using the Try type.

Scala try catch vs Try

Try was introduced in Scala 2.10 and behaves as a mappable Either without having to select right or left.

In the example below, taken from the Scala API:

def divide: Try[Int] = {  
  val dividend = Try(Console.readLine("Enter an Int that you'd like to divide:n").toInt)
  val divisor = Try(Console.readLine("Enter an Int that you'd like to divide by:n").toInt)
  val problem = dividend.flatMap(x => divisor.map(y => x/y))
  problem match {
    case Success(v) =>
      println("Result of " + dividend.get + "/"+ divisor.get +" is: " + v)
      Success(v)
    case Failure(e) =>
      println("You must've divided by zero or entered something that's not an Int. Try again!")
      println("Info from the exception: " + e.getMessage)
      divide
  }
}

You can see how, instead of using explicit try and catch to treat exceptions, Try is used to encapsulate the operation which is always an instance of either Success or Failure.

Benefits

You get, according again to the official documentation the:

[..] ability to pipeline, or chain, operations, catching exceptions along the way. You can map as you would a collection, an option or a right projection of an Either.

Furthermore, they encode exceptions in the Type system allowing for better documentation and clearer intention.
The Effective Scala[2] guide states:

using Option or com.twitter.util.Try are good, idiomatic choices, as they harness the type system to ensure that the user is properly considering error handling.

Start enforcing it today with Codacy

Login to your account and enable the pattern “Enforce usage of the Try object” to enforce it in your projects

1: Scala API http://www.scala-lang.org/api/current/index.html#scala.util.Try
2: Effective Scala http://twitter.github.io/effectivescala

Learn more about Scala

Check out other Scala resources on our blog.


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