Regex : Using Regex in Java 8

Question

I want to manipulate a String, my String are :

 String string = "dfwx--05-dfpixc3"

I want my output to be like :

dfwx--05
dfpixc3

So the separator is - and not --

moreover, can I solve this problem using Matcher class Pattern class ?

Because my String is variable There always a number after -- — CHARAFI Saad
– CHARAFI Saad, Commented Dec 23, 2019 at 19:41
You're using '-' as a field delimiter, and implicitly not allowing any of the fields themselves to start or end with '-'. That is, dfwx--05 is always a single field and cannot represent two fields dfwx and -05. I hope this is just a practice/learning and not in use with real data. :-) — Kaan
– Kaan, Commented Dec 23, 2019 at 20:13
Just note, that the title should be significant, not a standard one — Youcef LAIDANI
– Youcef LAIDANI, Commented Dec 23, 2019 at 21:06

Vishwa Ratna · Accepted Answer · 2019-12-24 07:23:49Z

7

You can use split with this regex \b-\b with Word Boundaries like so :

\b represents an anchor like caret (it is similar to $ and ^) matching positions where one side is a word character (like \w) and the other side is not a word character (for instance it may be the beginning of the string or a space character).

String[] split = string.split("\\b-\\b");

Because my String is variable There always a number after --

Another solution could be by using positive lookbehind, like so (?<=\d)- :

String[] split = string.split("(?<=\\d)-");

Outputs

[dfwx--05, dfpixc3]

edited Dec 24, 2019 at 7:23

Vishwa Ratna

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answered Dec 23, 2019 at 19:40

Youcef LAIDANI

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1 Comment

Vishwa Ratna Over a year ago

String str = "dfwx--05-dfpixc3"; Arrays.stream(str.split("\\b-\\b")).forEach(System.out::println); does the perfect job.

MonkeyZeus · Accepted Answer · 2019-12-23 20:59:30Z

5

You can make use of lookarounds:

(?<!-)-(?!-)

(?<!-) - make sure the preceding char is not a dash
- - make sure we are looking at a dash
(?!-) - make sure the following char is not a dash

If I'm not mistaken, the code would be:

string.split("(?<!-)-(?!-)");

I don't know which online tester is best for Java but see https://regex101.com/r/LVXDdH/1 for a PCRE example.

Thank you JGFMK for this Java specific test site:

https://repl.it/repls/ImpressionableBronzeMice

edited Dec 23, 2019 at 20:59

answered Dec 23, 2019 at 20:02

MonkeyZeus

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1 Comment

JGFMK Over a year ago

I would just do it like this. repl.it/repls/ImpressionableBronzeMice - Good point about additional dashes. I actually like your answer better personally than YCF_L's. Since it deals with the - character on it own. That in my eyes is cleaner/clearer.

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