Java regex special construct [duplicate]

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Possible Duplicate:

What is a regex “independent capturing group”?

Which is the difference between:

• (?:X) X, as a non-capturing 开发者_如何学Pythongroup and

• (?>X) X, as an independent,

  non-capturing group

I can't figure out how to use the last.

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You might want to look at this question:

What is a regex "independent capturing group"?