JS regex to Java, syntax issues

Question

I have this to big regex that I use in JavaScript to validate email address.

/^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/

When I try to used them in Java, I get syntax errors.

Unclosed character class near index 154 /^(([^<>()[]\.,;:\s@\"]+(.[^<>()[]\.,;:\s@\"]+)*)|(\".+\"))@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}])|(([a-zA-Z-0-9]+.)+[a-zA-Z]{2,}))$/ ^

I'm using http://www.regexplanet.com/ to test the regex.

Is there any way to convert or escape chars or something like this? Thanks!

you do know it's very hard to get a regex to validate an email (as per RFC 822), right? ex-parrot.com/pdw/Mail-RFC822-Address.html. See discussion here: stackoverflow.com/questions/201323/… — Lucas Pottersky
– Lucas Pottersky, Commented Nov 26, 2015 at 18:15
@guest271314 If a web form was the only way someone could send data to the server, sure. But it isn't, and believing it is leaves you wide open to the most trivial of hacks. — Dave Newton
– Dave Newton, Commented Nov 26, 2015 at 18:37
@guest271314 Use both client-side validation (for immediate, high-level feedback) and server-side validation to protect your data. — Dave Newton
– Dave Newton, Commented Nov 26, 2015 at 18:56

Andreas · Accepted Answer · 2015-11-26 19:28:50Z

1

This is the JS regex as a Java string literal:

"(([^<>()\\[\\].,;:\\s@\"]+(\\.[^<>()\\[\\].,;:\\s@\"]+)*)|(\".+\"))@((\\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\])|(([a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,}))"

The anchors (^$) have been removed, since they're not needed when calling matches().

All \, except \", have been doubled.

[ inside a class ([]) needed escaping, so escape added (\\[).

. inside a class ([]) don't need escaping, so escape removed.

- inside a class ([]) don't need escaping if placed last, so moved to end.

answered Nov 26, 2015 at 19:28

Andreas

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Community · Accepted Answer · 2017-05-23 10:27:09Z

1

I scaped some characters, the result is this:

/^
    (
        (
            [^<>()\[\]\\.,;:\s@\"]+
            (\.[^<>()\[\]\\.,;:\s@\"]+)*
        )
        |
        (
            \".+\"
        )
    )

    @

    (
        (\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])
        |
        (([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,})
    )

$/

regexplanet.com:link

Seems like the problem was that there are some [ unescaped.

Anyway I encorage you to see this question: What-is-the-best-java-email-address-validation-method

edited May 23, 2017 at 10:27

CommunityBot

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answered Nov 26, 2015 at 18:48

mayo

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