Finding Regex hard to learn

[Dan0100]

Hey guys,
I'm having a bit of trouble learning regex. I understand that the string.matches() method needs to match the whole string for it to return true in java.

At the moment I have this to check if there is what space at either the beginning or the end of the string. This works with the replace method but is missing something to ever return true with the matches() method:

string.matches("^[ \t]+|[ \t]+$");

All help would be greatly appreciated,
Thanks,
Dan

P.S. are there any really good resources that can teach regex I have tried google but it doesn't seem to sink in (also I am learning it in flash at the same time).

[DarrylBurke]

Hey guys,
I'm having a bit of trouble learning regex. I understand that the string.matches() method needs to match the whole string for it to return true in java.

At the moment I have this to check if there is what space at either the beginning or the end of the string. This works with the replace method but is missing something to ever return true with the matches() method:

string.matches("^[ \t]+|[ \t]+$");

The metacharacter of whitespace (presuming that's what you mean by "what space") is \s and you want to test for whitespace EITHER at the beginning OR at the end of the input. I'll presume that OR isn't an EXOR i.e. that a string with whitespace at both beginning AND end should also match.

So in plain English: match
the beginning of the input followed by whitespace followed by anything
or
anything followed by whitespace followed by the end of input

(untested -- test and report back)

"(^\\s.*)|(.*\\s$)"

Note that in a Java String literal, you have to excape the backslash with another backslash.

P.S. are there any really good resources that can teach regex I have tried google but it doesn't seem to sink in (also I am learning it in flash at the same time).

What's wrong with the very first hit on Google -- also IMO the best resource for learning RegEx?
Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns
But make sure you go through the documentation for Pattern so you don't miss out on the Java-specific constructs.

db

[Dan0100]

Thank you so much Darryl.Burke. Your regex worked perfectly.
O.K. so I guess it is just a case of me knuckling down and studying Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns.

Thank you again,
Dan