Question

I am interested in finding 7 words in a string.
These should appear in order separated by space.

Assuming that String regex has a string with the 7 words, I was interested if a match did not occur to reduce to 6,5,4 etc words.

A first regex I thought was:
\\b(?:word1(\\s+)word2(\\s+)word3(\\s+)word4(\\s+)word5(\\s+)word6(\\s+)word7)\\b

1. The above would occur by using a StringBuffer and after
   splitting the variable regex by space, I would construct the
   regular expression by append.
2. If I got no match I would loop again contructing the expression up
   to word6 etc and further reducing to word5 etc until I hit a match.

I am not sure I really like this approach.Can I improve it or do it in a more efficient way?

Answer 1

the greedy (default) will do what you want

\\b(?:word1(?:(\\s+)word2(?:(\\s+)(?:word3(\\s+)(?:word4(\\s+)(?:word5(\\s+)(?:word6(?:(\\s+)word7)?)?)?)?)?)?)?)\\b

this will first attempt to match everything and then leave off word7 then leave off word6 …