Strings

String interpolation

@main def interpolation(): Unit =
  val name = "Ada"
  val age = 36
  val price = 1234.5

  println(s"$name is $age years old")
  println(s"Next year: ${age + 1}")
  println(s"Name has ${name.length} letters")
  println(f"Price: $price%.2f")
  println(f"$name%-6s|$age%5d|")
  println(raw"Path: C:\temp\new")

Ada is 36 years old
Next year: 37
Name has 3 letters
Price: 1234.50
Ada   |   36|
Path: C:\temp\new

• s"..." — inserts $name, or any expression in ${ }.
• f"..." — adds printf-style formats after a value: %.2f (2 decimals), %5d (width 5), %-6s (left-aligned, width 6). It's type-checked: %d with a String is a compile error.
• raw"..." — no escape processing, so \t and \n stay as written.

Common methods

@main def stringMethods(): Unit =
  val text = "  Hello, Scala World  "
  val t = text.trim
  println(t)
  println(t.toUpperCase)
  println(t.length)
  println(t.replace("World", "Friends"))
  println(t.split(", ").toList)
  println(t.contains("Scala"))
  println(t.startsWith("Hello"))
  println(t.substring(7, 12))
  println(t.reverse)
  println("ha" * 3)

Hello, Scala World
HELLO, SCALA WORLD
18
Hello, Scala Friends
List(Hello, Scala World)
true
true
Scala
dlroW alacS ,olleH
hahaha

Scala's String is Java's String, with extra methods added — like reverse, *, and all the collection operations (a string is a sequence of characters).

Multi-line strings

@main def multiline(): Unit =
  val message =
    """Dear Ada,
      |Thanks for signing up.
      |The Scala team""".stripMargin
  println(message)

Dear Ada,
Thanks for signing up.
The Scala team

Triple quotes allow line breaks; stripMargin removes the indentation up to each |, so the text can be indented with the code.

Comparing strings

In Scala, == compares contents (unlike Java, where it compares references):

@main def compare(): Unit =
  val a = "scala"
  val b = "SCALA".toLowerCase
  println(a == b)
  println(a.equalsIgnoreCase("Scala"))
  println("apple" < "banana")

true
true
true