Try/Catch/Finally Expressions in Scala

Try/Catch/Finally expressions are used for catching and handling exceptions in Scala.

Like If/Else, it is an expression rather than a statement, which means that it actually yields a result. This paradigm better aligns with functional programming style.

The syntax mirrors match expressions in parts, meaning there are case statements inside the catch block to match the different possible exceptions.

The finally block is optional. Here's an example of a Try/Catch expression:

  val dividedNumber = try {
		10/0 // divide 10 by 0
	} catch {
		// Scala enters this catch block if there's any type of exception
		case e: ArithmeticException => 0 // if it is of the ArithmeticException type, then return 0
		// can enter additional case statements here
	}

The finally block will always run, whether or not an error is thrown, but it will not return a value. It is optional, and exclusively used for side effects (eg. printing lines to the console).

  val dividedNumber = try {
		10/0
	} catch {
		case e: ArithmeticException => 0
	} finally {
		println("Hello! This line will always run but is just a side effect :)")
	}

Some further things to note:

• Even though Try/Catch/Finally is an expression, you are able to just use it as a statement too and ignore the yielded value
• When catching exceptions, you can either return a value to recover (as above), or throw another exception (this exception will not be handled by the Try/Catch)

• Previous: If/Else Expressions in Scala