I am fairly new to using regex. I have a serial number which can take the following forms: VV-XXXXXX-P or VVXXXXXXP
If the hyphen variant is used, then the number of ‘X’ can be variable. For example 01-162-8 is equivalent to 010001628.
In order to identify the 2 formats, I have created the following regex’s:
String HYPHENS = ([0]{1}[13]{1}-[1-9]{1,6}-[0-9]{1})
String NO_HYPHENS = ([0]{1}[13]{1}[0-9]{6}[0-9]{1})
However the issue with the NO_HYPHENS variant is that it allows 0 anywhere in the sequence For example: 010010628 should not be a valid sequence because there’s a non leading 0.
Additionally, how would I create a regex that I can use to replace all 0 from the sequence but the first one? I have tried the following but it also replaces the first 0.
String code = 010001234;
code = code.replaceAll("0+", "");
How could I modify the regex’s to achieve this?
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Answer
You can use
String NO_HYPHENS = "0[13](?!0*[1-9]0)[0-9]{6}[0-9]";
code = code.replaceAll("(?!^)0(?!$)", "");
See the regex demo.
The 0[13](?!0*[1-9]0)[0-9]{6}[0-9] regex matches:
0– zero[13]– one or three(?!0*[1-9]0)– any zeros followed with a non-zero digit and then a zero is not allowed at this location[0-9]{6}– six digits[0-9]– a digit.
I understand you use it in Java with .matches, else, add ^ at the start and $ at the end.
Also, the (?!^)0(?!$) regex will match any zero that is not at the string start/end position.