How to split a string in java and include the delimiter

Question

I want to split this string "AHHHAAAAARTFUHLAAAAAHV" using a delimiter "AAAA" and save it to an array including the delimiter. (desired output: [AHHHA, AAAA, RTFUHLA, AAAA ,HV]). I have the following codes below but the output is not the same to my desired output.

  String y = "AHHHAAAAARTFUHLAAAAAHV";
  System.out.println(Arrays.toString(y.split("((?<=AAAA)|(?=AAAA))")));

OUPUT: [AHHH, A, AAA, A, RTFUHL, A, AAA, A, HV]

try Arrays.toString(y.split("(?=AAAA[^A]|(?<=AAAA(?=[^A])))")) ? — Pavneet_Singh
– Pavneet_Singh, Commented Mar 22, 2017 at 18:16
Your desired splitting rule is ambiguous. AHHHAAAAA could be split into either AHHH, AAAA, A or AHHHA, AAAA. What is your expected outcome for AAAAAAAAA (9 As)? AAAAA, AAAA, or A, AAAA, AAAA, or ...? — Socowi
– Socowi, Commented Mar 22, 2017 at 18:16
@Pavneet_Singh WOW! thank you that did the job! Thank you that helped a lot. — user3187367
– user3187367, Commented Mar 22, 2017 at 18:25
@Socowi I thought so. Im practically toying around the split function so i was confused. Btw thank you so much for the idea — user3187367
– user3187367, Commented Mar 22, 2017 at 18:25

Pavneet_Singh · Accepted Answer · 2017-03-22 18:51:34Z

1

You can use (?=AAAA[^A]|(?<=AAAA(?=[^A])))

(?=AAAA[^A] : look-ahead to match AAAA and a non A char

| : or

(?<=AAAA(?=[^A]))) : positive-look-behind to match AAAA with lookahead to make sure there is no A character

String y = "AHHHAAAAARTFUHLAAAAAHV";
System.out.println(Arrays.toString(y.split("(?=AAAA[^A]|(?<=AAAA(?=[^A])))")));

Output :

[AHHHA, AAAA, RTFUHLA, AAAA, HV]

edited Mar 22, 2017 at 18:51

answered Mar 22, 2017 at 18:26

Pavneet_Singh

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3 Comments

Wiktor Stribiżew Over a year ago

Maybe (?=AAAA(?!A)|(?<=AAAA(?!A))) is also good to use here.

Pavneet_Singh Over a year ago

@WiktorStribiżew i have tested negative look ahead against mine but seems like they are taking little more time though they are surely concise

Wiktor Stribiżew Over a year ago

Actually, I believe they will work differently as well. Anyway, it is just in case.

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