Java regex. Keep special characters only when they're surrounded by numbers

user_10919549 0
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I'm making an word frequency program and I'm trying to process text to make it manageable. I'm trying to remove all special characters except $%^*+-=,./<> which are a part of a number. I have virtually no experience with regular expressions and after reading a bunch on it, I tried using the negative lookadead and negative lookaround to get something like

   String replace =  "[^a-z0-9\\\\s] | (?<!\\d)[$%^*+\\-=,./<>_] | [$%^*+\\-=,./<>_](?!\\d)";
   text.replaceAll(replace, "");

In short I want "they're." to become "theyre" but I want "1223.444" to remain unchanged.

regex java
1 Answers

You can use

text = text.replaceAll(replace, "[\\p{P}\\p{S}&&[^$%^*+=,./<>_-]]|[$%^*+=,./<>_-](?!(?<=\\d.)\\d)", "");

Details:

  • [\p{P}\p{S}&&[^$%^*+=,./<>_-]] - a character class intersection construct that matches any punctuation (\p{P}) or symbol (\p{S}) except $, %, ^, *, +, =, ,, ., /, <, >, _ and -
  • | - or
  • [$%^*+=,./<>_-](?!(?<=\d.)\d) - a $, %, ^, *, +, =, ,, ., /, <, >, _ or - char that is not immediately followed with a digit which is in its turn not immediately preceded with a digit and any char (. is used to match the symbol/punctuation consumed with [$%^*+=,./<>_-]).
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