Java Reference
In-Depth Information
Special Characters Used in Regular Expressions
(continued)
Character
Examples
Function
^
/^A/
matches the fi rst but
not the second
A
in “
A man
called Adam
“
Matches the start of a line or of the
input
.
$
/r$/
matches only the last
r
in “
horror
“
Matches the end of a line or of the
input
.
*
/ro*/
matches
r
in
“
right
,“
ro
in “
wrong
,“
and “
roo
“ in “
room
“
Matches the preceding character zero or more times.
+
/l+/ matches l in “life,“
ll in “still,“ and lll in
“stilllife“
Matches the preceding character one or more times.
For example, /a+/ matches the a in “candy“ and all
the a's i n “caaaaaaandy.”
?
/Smythe?/ matches
“Smyth” and “Smythe”
Matches the preceding character once or zero times.
.
/.b/ matches the second
but not the fi rst ob in
“blob“
Matches any character apart from the newline
character.
(x)
/(Smythe?)/ matches
“Smyth“ and “Smythe“ in
“John Smyth and Rob
Smythe“ and allows the
substrings to be retrieved
as RegExp.$1 and
RegExp.$2 respectively.
Matches x and remembers the match. The matched
substring can be retrieved from the elements of the
array that results from the match, or from the RegExp
object's properties $1, $2 ... $9, or lastParen.
x|y
/Smith|Smythe/ matches
“Smith” and “Smythe”
Matches either x or y (where x and y are blocks of
characters).
{n}
/l{2}/
matches
ll
in
“
still
“ and the fi rst two
l
s in “
stilllife
“
Matches exactly
n
instances of the preceding charac-
ter (where
n
is a positive integer).
{n,}
/l{2,}/
matches
ll
in “
still
” and
lll
in
“
stilllife
”
Matches
n
or more instances of the preceding charac-
ter (where
n
is a positive integer).
{n,m}
/l{1,2}/
matches
l
in
“
life
“,
ll
in “
still
,“
and the fi rst two
l
s in
“
stilllife
“
Matches between
n
and
m
instances of the preceding
character (where
n
and
m
are positive integers).
[xyz]
[ab]
matches
a
and
b
;
[a-c]
matches
a
,
b
and
c
Matches any one of the characters in the square
brackets. A range of characters in the alphabet can be
matched using a hyphen.
