java regular expression matching

Question

What is the regular expression that can match the following 2 strings.

Hi<Dog>Hi and <Dog> in a given text.

Update:

What regex will match this one?

If you access the web site click the link below:

matches only till the first

Answer 1

Off the cuff I think it should be something like (.*)<XYZ>\1

Answer 2

Use http://www.weitz.de/regex-coach/ to check whether a regular expression matches a string

That's the only advice I can give you with the info you're giving us.

Answer 3

The pattern ^([a-z]*)<[A-Z]*>\1$ will match these strings (as seen on rubular.com):

ab<XYZ>ab
<XYZ>
bleh<FOO>bleh
<>

It will not match these:

ab<XYZ>de
x<XYZ>y
FOO<foo>FOO

That is, the pattern is something like

tag<CONTENT>tag

The same tag appears for both the "prefix" and the "suffix". Tag consists of zero or more lowercase letters. Content consists of zero or more uppercase letters. The prefix part is matched and captured by group 1, and then a backreference \1 is used to match that string again for the suffix.

The […] is a character class. Something like [aeiou] matches one of any of the lowercase vowels. [^…] is a negated character class. [^aeiou] matches one of anything but the lowercase vowels.

As a Java string literal, the pattern is "^([a-z]*)<[A-Z]*>\\1$".

Answer 4

Not sure what you try to do, but this captures all the possibly relevant groups:

([a-z]+)?(<[A-Z]+>)([a-z]+)?

Good Luck!