GNU Java Training Wheels 1.1: Packages in J.T.W. and Java

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## 5 Packages in J.T.W. and Java

The structure of a `package` mirrors the file system. For example you can have a `package` named (for argument’s sake) `pkg` which corresponds to a folder `pkg` in your `~/jtw-tutorials` folder. You can have a sub-package called (for argument’s sake) `inner` which will reside in the folder `~/jtw-tutorials/pkg/inner`. Even though the second `package` resides inside of the first `package`, they are still considered as separate packages.

There is a naming convention that I will not bother to use that helps to give unique names to your packages. If you own a website like `davinpearson.com` you can name your packages like so: `com/davinpearson/inner/inner2` where `com/davinpearson` where `com.davinpearson.inner` and `com.davinpearson.inner.inner2` are separate packages. The fact that I own the domain name `davinpearson.com` ensures that my `package` specification `com/davinpearson` is unique. The `com` comes first because it is the actual domain name rather than the `com` extension that is unique. It is therefore non-sensible to place any code directly in the `com` folder. So in effect we are piggy-backing onto an existing standard i.e. Internet Domain Names. The same feature is exploited by Websites which ask for your email address as your login, as email addresses are unique to individual people.

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