I'm currently learning regex in class, and my teacher insists on always using the `^` and `$` characters when working with the `matches()` method. However, I noticed that it seems to work fine without them. I'm confused about whether these symbols are just a best practice, if they serve a different purpose, or if there was a time in Java's history when not using them caused issues with outputs. Just to clarify, it appears that while the `matches()` method may not require them, they're necessary for the `Matcher` class to find a specific regex within a text. For instance, using `\\d{2}` returns false with `matches()`, but returns true with `find()` in `Matcher` if there are more than two digits present.
2 Answers
There's a useful overview of Java regex in the official documentation, but it can be confusing since it doesn’t clearly state which regex standard Java follows. A great way to experiment with regex is to use tools like regex101.com, which I've been using since 2014 for quick testing.
Regarding your teacher's insistence on using `^` and `$`, these characters ensure that your regex matches the entire string rather than just a part of it. Depending on your use case, you might need them, but sometimes it's unnecessary. It's often a good idea to include them to clarify your intent, even if it’s not strictly required.
Yeah, I didn’t realize the typo earlier. Thanks for confirming! My teacher gets pretty intense about it, but it seems like old advice or just a cautionary approach.
Thank you so much for the advice and the info!