Validating name through regex in Java

Question

I have to validate name using regex with the following conditions:

1.The Name should contain at least 1 word of length at least 3.

If there are more than 1 word then each word should be separated by single space and should not be empty.

The first part can be done as : [a-bA-Z]{3,}+ There are following constraints for the second one:

If there is only one word no extra space after the word should be included.
After the space there can be any number of characters.

Can anyone help me on this?

Tim Biegeleisen · Accepted Answer · 2020-02-29 09:40:23Z

3

I think this meets your requirements:

^[A-Za-z]{3,}(?: [A-Za-z]+)*$

Reading this out loud, the above pattern says to match at least one word of length 3 or more, which if alone should not be followed by whitespace. If two or more futher words be in the name, they should be separated by a single space.

answered Feb 29, 2020 at 9:40

Tim Biegeleisen

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4 Comments

JvdV Over a year ago

Sweet, I was thinking maybe using \p{L} in case you'd encounter some funky names with non-ascii characters =). Would not be uncommon over where I'm from.

kyabhft Over a year ago

I understand the first half. But what does (?: [A-Za-z]+)*$ mean?

Tim Biegeleisen Over a year ago

It means match space followed by a name, zero or more times. The ?: inside the parentheses just tells the regex engine not to bother capturing anything. Search SO on this if you have more doubts.

kyabhft Over a year ago

Got it. Thanks a lot for your help.

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