Java Reference
In-Depth Information
Here's an example that checks strings to see if they are palindromes: that is, if they are the
same forward and backward. To check for palindromes you first need to remove any punc-
tuation and ignore case before reversing the string:
def palindromes = '''
Able was I ere I saw Elba
Madam, in Eden, I'm Adam
Sex at noon taxes
Flee to me, remote elf!
Doc, note: I dissent. A fast never prevents a fatness. I diet on cod.
'''
palindromes.
eachLine
{
String str = it.trim().replaceAll(
/\W/
,'').toLowerCase()
assert str.
reverse
() == str
}
Once again, a little Groovy code packs a lot of power. The method
eachLine
has been
added to the
String
class to break multiline strings at line breaks. It takes a closure as
an argument. In this case, no dummy variables were used in the closure, so each string is
assigned to the default variable called
it
.
The it variable
In a closure, if no dummy name is specified the term
it
is used by default.
The
trim
method is applied to the line to remove any leading and trailing spaces. Then
the
replaceAll
method is used to replace all non-word characters with an empty string.
Finally, the string is converted to lowercase.
The assert test uses another method added by Groovy to
String
, called
reverse
. Java
has a
reverse
method in
StringBuffer
, but not
String
. Groovy adds the
re-
verse
method to
String
for convenience.
Groovy adds lots of methods to the Java standard libraries. Collectively these are known
as the
Groovy JDK
and are one of the best features of Groovy. The Groovy documentation
includes GroovyDocs for both the Groovy standard library and the Groovy JDK.
