Programming Grails - Cdn.oreilly.com

Using a StringBuilder (the preferred approach when concatenating in a loop) wouldn’t
be much better in this case. But using a GString (along with property syntax), we can
join the data in a single line of code:
def fullName = "$person.firstName ${person.initial ? person.initial + ' '
: ''}$person.lastName"
GStrings also work with multiline strings as long as you use three double quotes; this
is convenient for tasks such as filling in templates for emails:
def template = """\
Dear $name,
Thanks for signing up for the Ralph's Bait and Tackle online store!
We appreciate your business and look forward to blah blah blah …
Ralph
"""
Here, I’m using the backslash character at the beginning of the string to avoid having
an initial blank line. You can use three single quotes to create multiline strings, but they
behave like regular strings that use single quotes, in that they do not support expression
replacement.
Using the subscript operator lets you conveniently access substrings:
String str = 'Groovy Strings are groovy'
assert str[4] == 'v' // a String of length 1, not a char
assert str[0..5] == 'Groovy' // the first 6 chars
assert str[19..-1] == 'groovy' // the last 6 chars
assert str[15..17] == 'are' // a substring in the middle
assert str[17..15] == 'era' // a substring in the middle, reversed
Static this
Unlike Java where the this keyword only makes sense in instance scope, this resolves
to the class in static scope. One use of this feature is when defining static loggers. In
Log4j and SLF4J, you can define a logger with a class or the class name (or any string
you like), but in Java, there’s no way (no convenient one anyway) to get the class name
in static scope. This can lead to copy/paste problems. For example:
private static final Logger LOG = Logger.getLogger(Foo.class);
has the class hardcoded, so if you forget to change it and copy that to a different class,
you’ll be logging as the wrong category. Instead, in Groovy, you can use:
private static final Logger LOG = Logger.getLogger(this)
which is more portable (and similar to the analogous instance version private final
Logger log = Logger.getLogger(getClass())).
20 | Chapter 1: Introduction to Groovy