regex causing logic error

Question

private final String reg2 = "[A-Z][A-Za-z0-9_]+@[a-z]+[.com|.net][.sg|.cn|.au]?";

this line of code is supposed to be the regex for an email tester. the current email I'm using to test it is Kenny@gmail.com(imaginary of course). However, it seems to be always wrong. How do I change it?

Answer 1

It will be wrong because you are using character classes instead of alternative groups.

(\.com|\.net) - this is correct.

Your regex can match "Kenny@gmail.com" after a small enhancement (see demo here):

[A-Z][A-Za-z0-9_]+@[a-z]+(?:\.com|\.net)(?:\.sg|\.cn|\.au)?

See more on alternative lists here and on character classes here.