Question

I’m learning to use Java’s Pattern and Matcher, and this is an example code snippet in my book. It works as the author describes, but what I don’t get is why \\. ends up being a dot instead of a backslash (the \\ part) and a dot (the . part). Does the compiler not read from left to right?

import java.util.regex.*;
public class SplitTest {
   public static void main(String[] args)  {
       String input= "www.cs.cornell.edu";                          

      Pattern p = Pattern.compile("\\.");
      String pieces[] = p.split(input);
      for (int i=0; i<pieces.length; i++){
            System.out.println(pieces[i]);    
            }



   }
}

Answer 1

It’s being interpreted once when parsing the string literal, and once by the regex compiler.

"\\." -> "\." – string literal
"\." -> literal . – regex compiler