Pattern Matching

[Neh Agarwal]

I need to validate product version entered by the user. The allowed pattern is any alphanumeric and a dot, i.e allowed values are:
1
1as.1dfd
11.11.hjh etc.

I am using the pattern as ^(\\w+.?\\w+)+$
The only problem with the ablove pattern is if the user gives only 1 digit or 1 letter, it fails to be matched

Can you please suggest a valid pattern.

Thanks, Please Help!

[Henry Wong]

The only problem with the ablove pattern is if the user gives only 1 digit or 1 letter, it fails to be matched

The problem is caused by the fact that you have two word patterns (of one or more characters) -- making all words between the periods to be at least two or more characters.

You may want to make the optional period attached to a zero length look-ahead... Instead of this...

.?\\w+

try....

(\\.(?=\\w))?



And BTW, the period has special meaning in a regex -- you will need to escape it... which is what I did above.

Henry

[John de Michele]

I haven't tested this, but you may want to try ^(?:\\w+\\.?)+$

John.

[Piet Verdriet]

John de Michele wrote:I haven't tested this, but you may want to try ^(?:\\w+\\.?)+$

John.

That will also match a String like: "abc.def." (ie. a String ending with a DOT, which is not desired, if I understand the OP correctly).

[Piet Verdriet]

Neh Agarwal wrote:I need to validate product version entered by the user. The allowed pattern is any alphanumeric and a dot, i.e allowed values are:
1
1as.1dfd
11.11.hjh etc.

I am using the pattern as ^(\\w+.?\\w+)+$
The only problem with the ablove pattern is if the user gives only 1 digit or 1 letter, it fails to be matched

Can you please suggest a valid pattern.

Thanks, Please Help!

Correct, that is because you used \\w+ twice, so, the minimum length of a String must be 2 to be matched.
Also note that the short-hand-character-class \w matches an underscore as well. If this is not what you want, you should use the following character class:

"[a-zA-Z0-9]"

And the following regex will do the trick:

"^[a-zA-Z0-9]+(\\.[a-zA-Z0-9]+)*$"

[John de Michele]

Piet:

Oops! I think you're right. I forgot about the underscore and that pesky final dot.

John.

[Neh Agarwal]

Thanks a lot, it works perfectly