What happens is it works fine for the second line above "Master degree" as there is only 1 instance of the text, but for the other two lines the result is "greedy" as it does not stop tokenizing on matching the first instance of the items and returns instead something like "Higher education qualification ABC lorem ipsum DEF" or "Post-grad Certificate GHI lorem ipsum ABC". If I dont care about the subgroups I just keep all of them matching. Check Regex101 for the difference in number of steps between the two. The matched substring cannot be recalled from the resulting arrays elements ( 1,, n ) or from the predefined RegExp objects properties ( 1,, 9 ). I use non-capturing groups whenever possible. In these cases, non-matching groups simply wont contain.
The only difference between capture groups and non-capture groups is that the former captures. above, or in an alternative part of the expression that was not used of the match, like (bla) above. I need to extract (tokenize into columns) only "Higher education qualification" and "Master degree" and "Post-grad Certificate", etc. Non-capturing group: Matches 'x' but does not remember the match. See the Regular Expressions topic for the context of this essay. Qualification: Post-grad Certificate GHI lorem ipsum ABC Qualification: Master degree DEF lorem ipsum follows Unicode Technical Report 18: Unicode Regular Expression Guidelines. Qualification: Higher education qualification ABC lorem ipsum DEF Groups beginning with ( are pure, non-capturing groups that do not capture. If you are trying to match multiple groups the match results of each group is captured.
The real data I have is a bit more complex, but to try illustrate the challenge - given the following text: Non capturing groups Java regular expressions.
I've managed to complete 95% of the work, but there are some remaining items I just cannot get to tokenize correctly and hoping someone has an idea. What I am trying to do is tokenize out of a large block of text certain items like date of birth, nationality, job title, etc. Are non capturing groups faster 4 Answers. The regular expression a(bcb)c (capturing group) matches abcc and abc. Apologies if this has already been answered in the forums, but I have not been able to find it. An atomic group is a group that, when the regex engine exits from it, automatically throws away all backtracking positions remembered by any tokens inside the group.