Content in IntelliJ IDEA is a group of files that contain your source code, build scripts, tests, and documentation. These files are usually organized in a hierarchy. The top-level folder is called a content root.

Modules normally have one content root. You can add more content roots. For example, this might be useful if pieces of your code are stored in different locations on your computer.

At the same time, modules can exist without content roots. In this case, you can use them as a collection of dependencies for other modules.

The content root directory in IntelliJ IDEA is marked with the icon.

From the main menu, select File | Project StructureCtrl+Alt+Shift+S and click Project Settings | Modules.

Select the necessary module and then open the Sources tab in the right-hand part of the dialog.

Click Add Content Root and specify the folder that you want to add as a new content root.

To remove a content root, click the Remove content entry button (). IntelliJ IDEA marks the selected root as a regular folder. The folder itself and its contents will not be deleted.

Folders within a content root can be assigned to several categories.

Sources

This folder contains production code that should be compiled.

IntelliJ IDEA compiles the code within the Sources folder. That is why, do not place configuration files (the .idea folder or its content and the .iml file) to this folder. For more information about different types of settings, refer to Project, module, and global settings.

Generated Sources

The IDE considers that files in the Generated Sources folder are generated automatically rather than written manually, and can be regenerated.

Test Sources

These folders keep code related to testing separately from production code. Compilation results for sources and test sources are normally placed into different folders.

Generated Test Sources

The IDE considers that files in this folder are generated automatically rather than written manually, and can be regenerated.

Resources

(Java only) Resource files used in your application: images, configuration XML and properties files, and so on. During the build process, resource files are copied to the output folder as is by default. You can Change the output path for resource files in your project.

Similarly to sources, you can specify that your resources are generated. You can also specify which folder within the output folder your resources should be copied to.

Test Resources

These folders are for resource files associated with your test sources.

Excluded

Files in excluded folders are ignored by code completion, navigation and inspection. That is why, when you exclude a folder that you don't need at the moment, you can increase the IDE performance. Normally, compilation output folders are marked as excluded.

Apart from excluding the entire folders, you can also exclude specific files.

Marking folders as excluded doesn't affect deployment. For information on how to exclude files from deployment, refer to Exclude files and folders from uploading and downloading.

Right-click a folder in the Project tool window.

Select Mark Directory as from the context menu.

Select the necessary category.

This way, you can assign categories to subfolders as well.

To restore the previous category of a folder, right-click this folder again, select Mark Directory as, and then select Unmark as . For excluded folders, select Cancel Exclusion.

You can also configure folder categories in Project Structure | Modules | Sources.

Java files and binaries cannot be excluded.

If you don't need specific files, but you don't want to completely remove them, you can temporarily exclude these files from the project. Excluded files are ignored by code completion, navigation, and inspections.

To exclude a file, you need to mark it as a plain text file. You can always return excluded files to their original state.

Right-click the necessary file in the Project tool window.

Select Override File Type | Plain text.

Plain text files are marked with the icon.

To revert the changes, right-click the file and select Mark as from the menu.

In some cases, excluding files or folders one by one is not convenient. For example, this may be inconvenient if your source code files and files that are generated automatically (by a compiler, for instance) are placed in the same directories, and you want to exclude the generated files only. In this case, you can configure one or several name patterns for a specific content root.

If a folder or a filename located inside the selected content root matches one of the patterns, it will be marked as excluded. Objects outside the selected content root won't be affected.

All files within excluded folders will be excluded as well.

From the main menu, select File | Project Structure, or press Ctrl+Alt+Shift+S.

Click Modules under the Project Settings section, and then select a module.

If there are several content roots in this module, select the one that you want to exclude files or folders from.

In the Exclude files field located at the bottom of the dialog, enter a pattern. For example, enter *.aj*_test.go to exclude AspectJ files.

You can configure multiple patterns and separate them with the semicolon symbol (;).

Marking folders as excluded doesn't affect deployment. For information on how to exclude files from deployment, refer to Exclude files and folders from uploading and downloading.

In Java, you can assign a package prefix to a folder instead of configuring a folder structure manually. A package prefix can be assigned to source folders, generated source folders, test source folders and generated test source folders.

From the main menu, select File | Project Structure Ctrl+Alt+Shift+S and click Modules.

Select the necessary module and open the Sources tab.

In the right-hand pane, click next to Source Folders or Test Source Folders.

Specify the package prefix and click OK.

When you're building a project, the resources are copied into the compilation output folder by default. You can specify a different directory within the output folder to place resources.

This information is valid for projects that are built with the native IntelliJ IDEA builder. If you're using a build tool, such as Maven or Gradle, make all changes using the build file.

From the main menu, select File | Project Structure Ctrl+Alt+Shift+S and click Modules.

Select the necessary module and open the Sources tab.

In the right-hand pane, under Resource Folders or Test Resource Folders, click to the right of the necessary folder (folder path).

Specify the path relative to the output folder root, and click OK.