Try

A Try is a wrapper for a computation that might fail.

sealed abstract class Try[+T]
case class Failure[+T](t: Throwable) extends Try[+T]
case class Success[+T](value: T) extends Try[+T]

Usage

Suppose that we have a method that throws an error.

def unsafeMethod(): String = throw new RuntimeException("No string")

We can use Try to catch it.

val potentialFail = Try(unsafeMethod())
println(potentialFail)
// Failure(java.lang.RuntimeException: No string)

There is a sytex sugar.

val potentialFail = Try {
  unsafeMethod()
}

Utilities

• isSuccess / isFailure

  println(potentialFail.isSuccess) // false
  

• orElse

  val fallbackTry = Try(unsafeMethod())
    .orElse(Try(backupMethod()))
  

  Syntax sugar is:

  val fallbackTry = Try {
    unsafeMethod()
  } orElse Try {
    backupMethod()
  }
  
  println(fallbackTry) // Success(A default string)
  

• map, flatMap, filter

API Design

If your codes might throw an error, wrap them with Try.

def betterUnsafeMethod(): Try[String] = Try {
  throw new RuntimeException("No string")
}

def betterBackupMethod(): Try[String] = Try {
  "A default string"
}

So, we can use it better.

val betterTry = betterUnsafeMethod() orElse betterBackupMethod()