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- [0-9]{4}-[0-9]{4} would allow numbers such as: 1245-7783
- [0-9]+ EUR$ would allow price tags such as: 34 EUR
- [a-z]* would allow an empty string, or any lower case word such as: yellow
- Option [A,B] would allow a selection of options: Option A, Option B or both.
Detailed Documentation on Regex can be found here: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html It is quite technical though. A good website that could help further is https://www.freeformatter.com/java-regex-tester.html where you can test them and also have a less technical documentation with examples. Hope this helps.
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