How should one separate words in package names? Which of the following are correct?
com.stackoverflow.my_package(Snake Caseusing underscore)com.stackoverflow.my-package(Kebab Caseusing hyphens)com.stackoverflow.myPackage(Camel Case)com.stackoverflow.MyPackage(Pascal Case)
What is the general standard?
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Answer
Here’s what the official naming conventions document prescribes:
Packages
The prefix of a unique package name is always written in all-lowercase ASCII letters and should be one of the top-level domain names, currently
com,edu,gov,mil,net,org, or one of the English two-letter codes identifying countries as specified in ISO Standard 3166, 1981.Subsequent components of the package name vary according to an organization’s own internal naming conventions. Such conventions might specify that certain directory name components be division, department, project, machine, or login names.
Examples
com.sun.engcom.apple.quicktime.v2edu.cmu.cs.bovik.cheese
References
Note that in particular, anything following the top-level domain prefix isn’t specified by the above document. The JLS also agrees with this by giving the following examples:
com.sun.sunsoft.DOEgov.whitehouse.socks.mousefindercom.JavaSoft.jag.Oakorg.npr.pledge.driveruk.ac.city.rugby.game
The following excerpt is also relevant:
In some cases, the internet domain name may not be a valid package name. Here are some suggested conventions for dealing with these situations:
- If the domain name contains a hyphen, or any other special character not allowed in an identifier, convert it into an underscore.
- If any of the resulting package name components are keywords then append underscore to them.
- If any of the resulting package name components start with a digit, or any other character that is not allowed as an initial character of an identifier, have an underscore prefixed to the component.