Question

I would like to show only a-z0-9 in a string, and the other characters should be replaced by null string

String s=this.saveFileName.replaceAll("/[a-z0-9. ]/", "");

This those not work, any ideas why?

Answer 1

Try this:

String s = "abc123ABC!@#$%^;'xyz";
String newString = s.replaceAll("[^a-z0-9]", "");
//newString is now "abc123xyz"

This takes advantage of the negation (^) operator in character classes which basically says, “match everything except the following characters.”

Also, you don’t need slashes when defining Java regexes.