Backrefrences in multi-line java regex

Question

Trying to write a stylechecker for some code and using backrefrences in Java for a multiline regex... here's what the regex looks like

.*import com.+([a-zA-Z]+Factory\.class).*\\1.*

Basically, want to find the first instance of a factory class in my code. My example code looks like this:

import com.sample.OtherClass;
import com.sample.cool.SomeFactory.class;

// other nonsense

@Import(clazz = SomeFactory.class)
// other nonsense

My expected match would be the SomeFactory.class in the @Import statement, but it doesn't pick this up... any suggestions?

Do nor forget to use Pattern.DOTALL flag when you compile a pattern. — Zefick
– Zefick, Commented Sep 21, 2017 at 16:43

anubhava · Accepted Answer · 2017-09-21 18:59:29Z

1

You can use this regex:

(?s)import\s+com.+?\.([a-zA-Z]+Factory\.class).*(\1)

In Java use:

final String regex = "(?s)import\\s+com.+?\\.([a-zA-Z]+Factory\\.class).*(\\1)";

Captured group #1 is SomeFactory.class after import line and captured group #2 is SomeFactory.class after @Import line.

answered Sep 21, 2017 at 18:59

anubhava

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