PatternSyntaxException while using string,match()

Question

I'm getting a pattern syntax exception in this regular expression:

[^c]*[c]{freq}[^c]*

It checks for the multiple occurrence of the letter C (equal to frequency or amount of times).

Add the stacktrace please.

Jens
– Jens

2015-08-27 11:08:39 +00:00
Commented Aug 27, 2015 at 11:08 — Jens
– Jens, Commented Aug 27, 2015 at 11:08
Tell us sample input and output.

Manwal
– Manwal

2015-08-27 11:10:10 +00:00
Commented Aug 27, 2015 at 11:10 — Manwal
– Manwal, Commented Aug 27, 2015 at 11:10

anubhava · Accepted Answer · 2015-08-27 11:20:11Z

1

You cannot use freq variable in regex like this. Build your regex as a String:

String regex = "[^c]*c{" + freq + "}[^c]*";

If c is also a variable then use:

String regex = "[^" + c + "]*" + c + "{" + freq + "}[^" + c + "]*";

RegEx Demo

edited Aug 27, 2015 at 11:20

answered Aug 27, 2015 at 11:01

anubhava

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7 Comments

Subhash Over a year ago

this solves the error but i cant get the correct out put...can you help @anubhava ? What is wrong with this regular expression..?

Subhash Over a year ago

yes .. 2 appears consecutively at least twice wg: 22 or 122 or 222 or 220

Subhash Over a year ago

here c and freq are variables ... which are defined by user.. so c=2 and freq=2 as well..srry should have mentioned..

Subhash Over a year ago

ya thnx its working...it clicked to to me as well.!!

Subhash Over a year ago

Is there a way to check these regular expression on numbers without converting them into Strings...with String.matches() or is there any other function for that..?

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