CODEWITHSUNDEEP
javaregex
sanmianti
sanmianti

Reputation: 195

What is wrong with : Pattern pattern = Pattern.compile("\\");

I just want to use the regular expression to match the backslash (\) character, but it throws a PatternSyntaxException:

Exception in thread "main" java.util.regex.PatternSyntaxException: Unexpected internal error near index 1
\
 ^
    at java.util.regex.Pattern.error(Unknown Source)
    at java.util.regex.Pattern.compile(Unknown Source)
    at java.util.regex.Pattern.<init>(Unknown Source)
    at java.util.regex.Pattern.compile(Unknown Source)
    at helloworld.HelloWorld.main(HelloWorld.java:20)

Upvotes: 2

Views: 2352

Answers (1)

freedev
freedev

Reputation: 30087

You're just trying a regex using only the regex escape character \ (that's why is raised java.util.regex.PatternSyntaxException: Unexpected internal error near index 1 \)

Just to be clear, incidentally, the slash \ in Java is also the character used to identify the start of a escaped sequence (java escape characters) and has special meaning to the compiler. So if you want write a slash in a String you have to double it ("\\").

If you want write a regex that search a slash you must escape it, and translating the regex in a Java String you must double the slashes again.

So the regex for slash becomes "\\\\"

Upvotes: 2

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