Strings

String have characters, and may certain values. With string manipulation methods in Scala 3.3, we can capitalize the first letter in this string.

In this language, we can access many functions that act upon strings. To uppercase the first letter, we invoke "capitalize" on a string.

Capitalize example

Here we create a constant string. The val means it is constant and we cannot reassign "name." We then capitalize the string.

object Program {
    def main(args: Array[String]): Unit = {
        // This is a string.
        val name = "plutarch"

        // Use the capitalize function to uppercase the first letter.
        val cap = name.capitalize
        println(cap)
    }
}
Plutarch

ToUpperCase, toLowerCase

String manipulation in Scala is done in a standard way. We call toUpperCase and toLowerCase to get copied and modified strings.

object Program {
    def main(args: Array[String]): Unit = {
        val name = "don quixote"

        // Uppercase all letters in the string.
        // ... The space is left unchanged.
        val upper = name.toUpperCase()
        println(upper)

        // Lowercase the letters.
        val lower = upper.toLowerCase()
        println(lower)
    }
}
DON QUIXOTE
don quixote

Multiply

Scala has special string operators. The star operator (an asterisk) concatenates a string the number of times we specify. This helps make whitespace and separators.

object Program {
    def main(args: Array[String]): Unit = {
        // Multiply this string (concatenate it repeatedly).
        val letters = "abc" * 3
        println(letters)

        // Create a string of nine hyphens.
        val separator = "-" * 9
        println(separator)
    }
}
abcabcabc
---------

Reverse

In some languages, we must develop custom string reversal methods. But in Scala we can use reverse from scala collection IndexedSeqOptimized.

object Program {
    def main(args: Array[String]): Unit = {
        val id = "x100"
        // Use reverse from scala.collection.IndexedSeqOptimized.
        val result = id.reverse

        // The characters in the string are now reversed.
        println(id)
        println(result)
    }
}
x100
001x

String equals

In Scala the double-equals operator "==" compares the character data of Strings, not the object identities. Here we test string equality.

object Program {
    def test(combined: String, left: String, right: String) = {
        // The equals operator tests the String's data.
        // ... It compares characters.
        if (combined == left + right) {
            println(s"$combined=true")
        } else {
            println(s"$combined=false")
        }
    }
    def main(args: Array[String]): Unit = {
        // These print true.
        test("abcd", "ab", "cd")
        test("catdog", "cat", "dog")
        // This prints false.
        test("xxyy", "ef", "gh")
    }
}
abcd=true
catdog=true
xxyy=false

Split

For strings with formatted data, split is often useful. We can invoke split in Scala. And with an array, we can split on more than one delimiter character.

Strip

With stripLineEnd we remove unwanted trailing newlines. And stripMargin provides more advanced whitespace-trimming behavior.

Scala provides helpful functions on strings. These enable us to manipulate and use strings without custom code. With capitalize, for example, we uppercase the first letter.