Java Regex Escape Characters

Question

I\'m learning Regex, and running into trouble in the implementation.

I found the RegexTestHarness on the Java Tutorials, and running it, the following s

Answer 1

My pattern is any double digit or single digit preceded by a space, followed by a period.)

Correct regex will be:

Pattern pattern = Pattern.compile("(\\s\\d|\\d{2})\\.");

Also if you're getting regex string from user input then your should call:

Pattern.quote(useInputRegex);

To escape all the regex special characters.

Also you double escaping because 1 escape is handled by String class and 2nd one is passed on to regex engine.