Number Parsing in Scala

Parsing numbers from strings is a basic but common task in many programs; here’s how to do it in Scala.

import scala.util.Try

object NumberParsing {
  def main(args: Array[String]): Unit = {
    // With toDouble, we parse the string to a Double
    val f = "1.234".toDouble
    println(f)

    // For parsing integers, we can use toInt
    val i = "123".toInt
    println(i)

    // Scala doesn't have built-in hex parsing, but we can use Integer.parseInt
    val d = Integer.parseInt("1c8", 16)
    println(d)

    // For unsigned integers, Scala doesn't have a direct equivalent
    // We can use Long to represent larger numbers
    val u = "789".toLong
    println(u)

    // toInt is a convenience method for basic base-10 int parsing
    val k = "135".toInt
    println(k)

    // Parse functions throw exceptions on bad input
    // We can use Try to handle potential errors
    val result = Try("wat".toInt)
    println(result) // prints Failure(java.lang.NumberFormatException: For input string: "wat")
  }
}

To run the program, save it as NumberParsing.scala and use scala:

$ scala NumberParsing.scala
1.234
123
456
789
135
Failure(java.lang.NumberFormatException: For input string: "wat")

In Scala, we use methods like toDouble, toInt, and toLong for parsing numbers from strings. These methods are available on string objects directly, which makes the syntax more concise compared to using separate functions.

For parsing hexadecimal numbers, we use Integer.parseInt with a radix of 16. Scala doesn’t have a direct equivalent to Go’s ParseUint, but we can use toLong to handle larger numbers.

Error handling in Scala is typically done using Try, Option, or exceptions. In this example, we’ve used Try to demonstrate how to handle potential parsing errors.

Next, we’ll look at another common parsing task: URLs.

Writing Files in Scala

Url Parsing in Scala

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Number Parsing in Scala