java - Difficulty with a simple regex for .obj files -

I am trying to parse lines of the form:

  command arg1 [ Arg2, ... argn]  

like:

> usemtl weasels

or

  f 1/2/3 4/5/6 7/8/9  

Here's my Reggae:

  ^ (\\ W +) ($ \\ S +) +) $  

When I parse the "usemtl weasels" line, I get the following capturing groups:

 <0> Match 0: 'USMTL Weasels' match 1: 'USMTL' match 2: 'electricity'  

Why start with another match group Location? It does not appear in Rubular. Grouping in Java Regex is a bit awkward Group 0 gives you a complete mail of your regex - all of these are regex.

Implementation is similar to what I know. But n ( n = 1) will give you n the last match of the declared group, not n got the match.

Your second match gives you 'Weasels' with a prominent space, because your pattern is empty, you declare your second group ((\\ S +) +) And this group gives you another match.

If you apply your pattern to string abcd , your group will be 0 abcd , group 1 will a , Group 2 will be bcd and group 3 will be d , because it is your third declared (internal) group (\\ S +) .