regular expression in java question!

[yang tao]

hi guys

i want a string with 2 lower case, 2 upper case, 2 numeric chars in any order such as, 12aaCC, a2A9cC

how can i do that in regular expression?

i am stucked here for a while!

help please

thank you
[ October 06, 2008: Message edited by: yang tao ]

[Campbell Ritchie]

Split the String into a char[] array, sort the array, create a new String, then try a regular expression.

That is one possibility; there are bound to be others.

[James Sabre]

"(?=(.*[0-9].*){2}.*)(?=(.*[a-z].*){2}.*)(?=(.*[A-Z].*){2}.*)([0-9a-zA-Z]{6})"

[Ilja Preuss]

Originally posted by James Sabre:
"(?=(.*[0-9].*){2}.*)(?=(.*[a-z].*){2}.*)(?=(.*[A-Z].*){2}.*)([0-9a-zA-Z]{6})"

That doesn't match the second example, as far as I can tell?

[yang tao]

thank you for you help

[Campbell Ritchie]

You're welcome

For the benefit of future generations of learners, please post what you used in the end.

[James Sabre]

Originally posted by Ilja Preuss:


That doesn't match the second example, as far as I can tell?

It does for me! Test code

        String regex = "(?=(.*[0-9].*){2}.*)(?=(.*[a-z].*){2}.*)(?=(.*[A-Z].*){2}.*)([0-9a-zA-Z]{6})";
        boolean result = "a2A9cC".matches(regex);
        System.out.println(result);

[Ilja Preuss]

Originally posted by James Sabre:


It does for me! Test code

        String regex = "(?=(.*[0-9].*){2}.*)(?=(.*[a-z].*){2}.*)(?=(.*[A-Z].*){2}.*)([0-9a-zA-Z]{6})";
        boolean result = "a2A9cC".matches(regex);
        System.out.println(result);

Oh, I see. Stupid me...

Clever regular expression. I wonder whether it might be a bit *too* clever, if you know what I mean...

[James Sabre]

Originally posted by Ilja Preuss:


Oh, I see. Stupid me...

Clever regular expression. I wonder whether it might be a bit *too* clever, if you know what I mean...

Esoteric - yes. Clever - not really - just a simple use of 'positive lookahead'.

[Piet Verdriet]

Originally posted by James Sabre:
"(?=(.*[0-9].*){2}.*)(?=(.*[a-z].*){2}.*)(?=(.*[A-Z].*){2}.*)([0-9a-zA-Z]{6})"

You could write it a bit more compact:

"(?=(.*[a-z]){2})(?=(.*[A-Z]){2})(?=(.*\d){2}).{6}"

since you don't need all the dot-stars, which makes it even slightly more readable!
; )

[yang tao]

lol, thank you for your solution

[James Sabre]

Originally posted by Piet Verdriet:


You could write it a bit more compact:

"(?=(.*[a-z]){2})(?=(.*[A-Z]){2})(?=(.*\d){2}).{6}"

since you don't need all the dot-stars, which makes it even slightly more readable!
; )

Yes. Much better. I had not taken the logic far enough having failed to deduce that since each of the 'look-a-heads' dictate two or more characters from their acceptance class then one just has to make sure that there are 6 characters total. Nice.

[Ilja Preuss]

Originally posted by James Sabre:

I had not taken the logic far enough having failed to deduce that since each of the 'look-a-heads' dictate two or more characters from their acceptance class then one just has to make sure that there are 6 characters total.

Perhaps you know understand what I mean by "clever"...

[James Sabre]

Originally posted by Ilja Preuss:


Perhaps you know understand what I mean by "clever"...

Though the regex I posted worked it was not 'clever'. The improved one is clever.