String Interpolators

This is the third of three lessons on the Scala String data type.

String interpolators:

• Use to put variables and expressions in strings
• Use to create a String
• Use when printing information
• Use instead of + (adding things to strings)

val fname = "Alvin"
val lname = "Alexander"
val fullName = fname + " " + lname     // don't do
val fullName = s"$fname $lname"

When you have expressions in strings, use {}:

// example:
val rez = s"${1 + 1}"

// example:
case class Person(firstName: String, lastName: String)
val p = Person("Alvin", "Alexander")
val fullName = s"${p.firstName} ${p.lastName}"

Other interpolators

• The beauty of this is the consistency
• s is the main interpolator
• f is used for formatted output
• raw is another
  • println(raw"foo\nbar") prints "foo\nbar"

Here’s an example of f:

val name = "Fred"
val age = 33
val weight = 200.00

s"$name is $age years old, and weighs $weight pounds."

f"$name is $age years old, and weighs $weight%.2f pounds."

Write your own interpolator

• sql
• My Q interpolator

Summary

• Use s"" and not +
• Use {} to enclose expressions
• s, f, and raw are built in
• Can write your own interpolators (like sql or Q)