Java Reference
In-Depth Information
18
19
// replace 'stars' with 'carets'
20
firstString = firstString.replaceAll(
"stars"
,
"carets"
);
21
22
System.out.printf(
23
"\"carets\" substituted for \"stars\": %s%n"
, firstString);
24
25
// replace words with 'word'
26
System.out.printf(
"Every word replaced by \"word\": %s%n%n"
,
27
firstString.replaceAll(
"\\w+"
,
"word"
)
);
28
29
System.out.printf(
"Original String 2: %s%n"
, secondString);
30
31
// replace first three digits with 'digit'
32
for
(
int
i =
0
; i <
3
; i++)
33
secondString = secondString.replaceFirst(
"\\d"
,
"digit"
);
34
35
System.out.printf(
36
"First 3 digits replaced by \"digit\" : %s%n"
, secondString);
37
38
System.out.print(
"String split at commas: "
);
39
String[] results = secondString.split(
",\\s*"
);
// split on commas
Arrays.toString(results)
40
System.out.println(
);
41
}
42
}
// end class RegexSubstitution
Original String 1: This sentence ends in 5 stars *****
^ substituted for *: This sentence ends in 5 stars ^^^^^
"carets" substituted for "stars": This sentence ends in 5 carets ^^^^^
Every word replaced by "word": word word word word word word ^^^^^
Original String 2: 1, 2, 3, 4, 5, 6, 7, 8
First 3 digits replaced by "digit" : digit, digit, digit, 4, 5, 6, 7, 8
String split at commas: ["digit", "digit", "digit", "4", "5", "6", "7", "8"]
Fig. 14.23
|
String
methods
replaceFirst
,
replaceAll
and
split
. (Part 2 of 2.)
Method
replaceAll
replaces text in a
String
with new text (the second argument)
wherever the original
String
matches a regular expression (the first argument). Line 15
replaces every instance of
"*"
in
firstString
with
"^"
. The regular expression (
"\\*"
)
precedes character
*
with two backslashes. Normally,
*
is a quantifier indicating that a reg-
ular expression should match
any number of occurrences
of a preceding pattern. However,
in line 15, we want to find all occurrences of the literal character
*
—to do this, we must
escape character
*
with character
\
. Escaping a special regular-expression character with
\
instructs the matching engine to find the actual character. Since the expression is stored in
a Java
String
and
\
is a special character in Java
String
s, we must include an additional
\
. So the Java
String
"\\*"
represents the regular-expression pattern
\*
which matches a
single
*
character in the search string. In line 20, every match for the regular expression
"stars"
in
firstString
is replaced with
"carets"
. Line 27 uses
replaceAll
to replace
all words in the string with
"word"
.
