I'M trying to detect a regex in a string; if

Question

I'M trying to detect a regex in a string; if

detected I'd change the recognized chars with other chars,. How could I do?

I tried something like:

Pattern pattern = Pattern.compile("[^A-Za-z0-9]");
Matcher match;
risultato.append(i+"° "+element.getKey().replaceAll(pattern.pattern(),match.group())+": "+element.getValue()+"\n");

But it's not working at all (risultato is a StringBuilder)