CODEWITHSUNDEEP
javaregex
Learner
Learner

Reputation: 544

Regarding regex whitespace

I have a small query regarding representing the space in java regular Expression.

I want to restrict the name and for that i have defined an pattern as

Pattern DISPLAY_NAME_PATTERN = compile("^[a-zA-Z0-9_\\.!~*()=+$,-\s]{3,20}$");

but eclipse indicating it as error "Invalid escape sequence".It is saying it for "\s" which according to

http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

is a valid predefined class.

What am i missing.Could anyone help me withit.

Thanks in advance.

Upvotes: 0

Views: 602

Answers (1)

Avinash Raj
Avinash Raj

Reputation: 174696

You need to escape the \ in \s one more time. And also, you don't need to escape the . inside a character class. . and \\. inside a character class matches a literal dot.

Pattern DISPLAY_NAME_PATTERN = Pattern.compile("^[a-zA-Z0-9_.!~*()=+$,\\s-]{3,20}$");

And also put the - at the first or at the last inside the character class. Because - at the center of character class may act as a range operator. regex.PatternSyntaxException: Illegal character range exception is mainly because of this issue, that there isn't a range exists between the , and \\s

If you want to do a backslash match, then you need to escape it exactly three times.

Pattern DISPLAY_NAME_PATTERN = Pattern.compile("^[a-zA-Z0-9_.\\\\!~*()=+$,\\s-]{3,20}$");

Example:

System.out.println("foo-bar bar8998~*foo".matches("[a-zA-Z0-9_.\\\\!~*()=+$,\\s-]{3,20}"));   // true
System.out.println("fo".matches("[a-zA-Z0-9_.\\\\!~*()=+$,\\s-]{3,20}"));  // false

Upvotes: 1

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