昨天看到有人用str.split("\\s+")今天又看到"420348092".matches("\\d+")
"fajsdkfjaskdfj".matches("\\w+");请问这些 "//什么的" 是什么东西?
是不是正则表达式?
"fajsdkfjaskdfj".matches("\\w+");请问这些 "//什么的" 是什么东西?
是不是正则表达式?
解决方案 »
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\\d表示 0-9 的数字,
\\s表示 空格,回车,换行等空白符,
\\w表示单词字符(数字字母下划线)
+号表示一个或多个的意思,所以...
c
The character c
\unnnn, \xnn, \0n, \0nn, \0nnn
The code unit with the given hex or octal value
\t, \n, \r, \f, \a, \e
The control characters tab, newline, return, form feed, alert, and escape
\cc
The control character corresponding to the character c
Character Classes
[C1C2. . .]
Any of the characters represented by C1, C2, . . . The Ci are characters, character ranges (c1-c2), or character classes
[^. . .]
Complement of character class
[ . . . && . . .]
Intersection of two character classes
Predefined Character Classes
.
Any character except line terminators (or any character if the DOTALL flag is set)
\d
A digit [0-9]
\D
A nondigit [^0-9]
\s
A whitespace character [ \t\n\r\f\x0B]
\S
A non-whitespace character
\w
A word character [a-zA-Z0-9_]
\W
A nonword character
\p{name}
A named character class—see Table 12-9
\P{name}
The complement of a named character class
Boundary Matchers
^ $
Beginning, end of input (or beginning, end of line in multiline mode)
\b
A word boundary
\B
A nonword boundary
Syntax
Explanation
\A
Beginning of input
\z
End of input
\Z
End of input except final line terminator
\G
End of previous match
Quantifiers
X?
Optional X
X*
X, 0 or more times
X+
X, 1 or more times
X{n} X{n,} X{n,m}
X n times, at least n times, between n and m times
Quantifier Suffixes
?
Turn default (greedy) match into reluctant match
+
Turn default (greedy) match into possessive match
Set Operations
XY
Any string from X, followed by any string from Y
X|Y
Any string from X or Y
Grouping
(X)
Capture the string matching X as a group
\n
The match of the nth group
Escapes
\c
The character c (must not be an alphabetic character)
\Q . . . \E
Quote . . . verbatim
(? . . . )
Special construct—see API notes of Pattern class
==================================
说的好