Easy way to convert regex to a java compatible regex?

Question

I have a regex defined in Python/Ruby/PHP that is like this

\"(forumdisplay.php\\?.*page=%CURRENTPAGE%)\"

When I do it for Java, I have to

Answer 1

Note that this is not the Java regular expression engine that requires the double backslashes, but the Java compiler. When you write the following in Java source code:

"(forumdisplay.php\\?.*page=%CURRENTPAGE%)"

the Java compiler interprets this as the string:

(forumdisplay.php\?.*page=%CURRENTPAGE%)

The Java regular expression engine then does exactly the same thing as other regular expression engines - the question mark (because it is escaped) is treated literally.

A similar thing happens in Python - the two strings below are identical:

r"(forumdisplay.php\?.*page=%CURRENTPAGE%)"
"(forumdisplay.php\\?.*page=%CURRENTPAGE%)"

This is using the Python r notation for a "raw" string where backslashes are not interpreted by the compiler.