In Java, should I create a new package, folder or source folder?

There are a few questions about so, but I'm completely unfamiliar with java development. I don't know the correct method

I have a c# solution that contains two projects (my application and a unit test project). In the application, most things are placed in folders, such as Interface, exception, etc

I tried to recreate it in Java / eclipse, but I don't know how I finally got a lot of bags. It sounds really bad I also tried to add a source folder, but it ended up outside the package

Can anyone point me in the right direction?

That is, what should I use to represent my unit test project / unit test set, and subfolders for organizing content only

Edit: it also indicates that the default package is not recommended What should I do?

Editor 2: This is what it looks like Does this look a little fuzzy? My original c# solution is on the right

Solution

In a typical Java eclipse project, you will have one or more source folders (for example, one for application code and one for unit testing)

Each folder contains a package tree, usually starting with your basic package, such as com mycompany. myapp.

To avoid name conflicts, package names usually begin with the domain name of the entity that is the author of the code, starting from the top-level domain and back (more general to more specific) In this way, the fully qualified name of each class is unique For example, if Google creates a class called list, it will be called com google. List, and it won't work with existing Java util. List interface conflict

You can include an unlimited number of packages in this base package, for example:

com.mycompany.myapp.persistence
com.mycompany.myapp.domain
com.mycompany.myapp.services
com.mycompany.myapp.web

It all depends on your project and how you want to organize your code and classes

At the logical level, packages are named with points as separators They contain Java classes

At the physical disk level, each package is a directory Java classes are included in Java files (the most common is one class per file)

In eclipse, "source folder" is a folder inside the project, which eclipse knows contains java source files When the project is built, it will be compiled and included in the output (such as jar files)

In eclipse, you usually view them at the logical level, displaying packages When you tell eclipse to "create a new package", it will create a directory for you For example, if you tell it to create com mycompany. Myproject package, which will automatically create a com folder containing the mycompany folder, which contains the myproject folder