Scala vs Groovy: Strings (Part 1)

Single Line Strings

I'm going to start the comparison of string handling in Scala and Groovy with a look at single line strings - the sort of string found in Java.

String s = "Hello, Java!";

Scala's basic string handling is just like Java (but with Scala's syntax and type inference):

var s: String = "Hello, Scala!"
var s2 = "Hello Type Inferer!"

Groovy has both Java-esque strings that are enclosed in double quotes as well as strings that are enclosed in single quotes.

def s = "Groovy's double quoted String"
def s2 = 'A "single quoted" Groovy String'

Groovy also has a third syntax for strings, using forward slashes

def s3 = /Slashy String/

All of the above are java.lang.String - however in Groovy, double quoted strings can become "GStrings". GStrings contain an expression contained in a ${ } block (something that will be familiar to anyone who has written JSP pages). For example:

def x = 4
def gs = "the value of x is: ${x}"
println gs

will print:

the value of x is: 4

Double quoted strings only get promoted to GStrings when they contain ${some expression}. If they don't, then they're plain old java.lang.String strings.


Multi-line Strings

Both Scala and Groovy support multi-line strings. Both use a similar syntax - the triple quote:

var ms = """This is
a Scala multi-line
String"""

def ms = """This is
a Groovy ${lines}
String"""

You'll notice that in Groovy, multi-line strings get promoted to GStrings as well.

Character

While looking at Strings, we should also look at Character. In a manner not dissimilar to Java, a Character in Scala is defined by a single character in single quotes:

val c = 'd'

In Groovy, Characters can't be created directly. This:

def c = 'd'

creates a String, not a Character. Instead, you need to write this:

def c = 'd' as char

which will create a String and then use some dynamic magic to convert it to a Character



End of Part 1

That's it for the basic comparison. However, both languages have syntactic sugar that gets layered onto strings, but that really should be a post on it's own.