IntelliJ IDEA 2019.2 Help

Configuring projects

Projects in IntelliJ IDEA allow you to conveniently manage modules and share settings between them. These settings include an SDK, a language level, and a compiler output.

Modules are independent entities. Each module can have its own settings and can be configured to develop framework-specific applications. Modules can reference other modules, that is depend on each other.

In IntelliJ IDEA, you can integrate projects with build tools, such as Maven or Gradle. In this case, the IDE will provide you with coding assistance for editing the build file, code completion, inspections and quick-fixes, refactorings, and so on.

Invalidate caches

IntelliJ IDEA caches a great number of files, therefore the system cache may become overloaded. Sometimes the caches will never be needed again, for example, if you work with frequent short-term projects.

When you invalidate the cache, IntelliJ IDEA rebuilds all projects ever run in the current version of the IDE.

Clear the system cache

  1. From the main menu, select File | Invalidate Caches/Restart.

  2. In the Invalidate Caches dialog, select an action. You can invalidate the caches and restart the IDE, invalidate the caches without restarting the IDE, or just restart the IDE.

Path variables

Path variables are placeholders that stand for paths to resources linked to your project. They provide sharing flexibility as you do not have to reference a fixed location on your computer.

Path variables are useful if, for example, you have a third-party library defined at the project or module level, and it is stored outside the project directory or module content roots (for projects shared through VCS). Such a library is referenced by its absolute path and there is no guarantee that this path is the same on computers of your teammates. If you use a path variable, you make the path relative as each variable is configured on each computer individually.

In IntelliJ IDEA, there are some pre-defined variables:

  • $USER_HOME$: stands for your home directory.

  • $PROJECT_DIR$: stands for the directory where your project is stored.

  • $MODULE_DIR$: stands for the directory that keeps module configuration files IML.

To configure path variables, in the Settings/Preferences dialog Ctrl+Alt+S, select Appearance & Behavior | Path Variables.

Path Variables dialog

Example: create a new path variable

For example, you have a third-party library that is not stored in your project directory. If you want to make sure that the path is correct on your teammates' computers after they update the project from VCS, you can create a new variable.

  1. In the Settings/Preferences dialog (Ctrl+Alt+S), select Appearance & Behavior | Path Variables, and click the Add button.

  2. Enter the name of the new variable (for example, PATH_TO_LIB) and its value that points to the library location on your disk.

  3. Share the IML file through your version control system.

  4. After your teammates update their projects from VCS, they will change the PATH_TO_LIB variable value so that it points to the library location on their computers.

Ignore path variables

When you open a project, IntelliJ IDEA checks if there are any unresolved path variables. If the IDE detects any, it will ask you to define values for them. If for some reason you do not want to do that (for example, if you are not going to use files or directories with the unresolved path variables), you can add them to the list of ignored variables.

You can also use the list of ignored variables if, for example, a program parameter passed to the JVM in a run/debug configuration has the same format as an internal ($SOME_STRING$) path variable. In this case, you can add this parameter to the list of ignored variables in order to avoid confusion. Enter SOME_STRING to the Ignored Variables field in the Path Variables dialog.

Resource files

Resources include properties files, images, DTDs, and XML files. These files are located in the classpath of your application, and are usually loaded from the classpath using the following methods:

  • ResourceBundle.getBundle() for properties files and resource bundles

  • loadResourceAsStream() for icons and other files

When building an application, IntelliJ IDEA copies all resources into the output directory, preserving the directory structure of the resources relative to the source path. The following file types are recognized as resources by default:

The pattern of recognized resource files can be configured as a regular expression in the Compiler dialog (Settings/Preferences Ctrl+Alt+S | Build, Execution, Deployment | Compiler). Using the Resource Patterns field, you can add your own file extensions and create custom list of resources.

Last modified: 17 October 2019