Question

I want to write a simple validator to throw an exception if a String contains “illegal characters”, specifically:

~, @, +, % and |

I’m searching for the cleanest way of doing this, and was hoping that there was a way to define a “blacklist” regex that might look something like:

String blacklist = "~@+%|";
String toValidate = getInputFromUser();

if(toValidate.matches(blacklist))
    throw new RuntimeException("Illegal characters found!");

However I know that the regex is incorrect. Am I heading in the right direction or am I way off base (i.e. is there a much simpler solution)? Thanks in advance!

Answer 1

The regex should be ^.*[~@+%|].*$

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Alternatively you can use [~@+%|] with find method instead of matches