Matching a whole word with leading or trailing special symbols like dollar in a string

Question

I can replace dollar signs by using Matcher.quoteReplacement. I can replace words by adding boundary characters:

from = \"\\\\b\" + from + \"\         


        

Answer 1

Use unambiguous word boundaries, (? and (?!\w), instead of \b that are context dependent:

from = "(?

See the regex demo.

The (? is a negative lookbehind that fails the match if there is a non-word char immediately to the left of the current location and (?!\w) is a negative lookahead that fails the match if there is a non-word char immediately to the right of the current location. The Pattern.quote(from) is necessary to escape any special chars in the from variable.

See the Java demo:

String line = "add, $temp4, $temp40, 42";
String to = "register1";
String from = "$temp4";
String outString;

from = "(? add, register1, $temp40, 42