The IntelliJ Platform ensures that only one instance of a service is loaded even though it is called several times.
A service must have an implementation class that is used for service instantiation. A service may also have an interface class used to obtain the service instance and provide the service's API.
The IntelliJ Platform offers three types of services: application level services (global singleton), project level services, and module level services. For the latter two, a separate instance of the service is created for each instance of its corresponding scope, see Project Model Introduction.
Project/Module level service constructors can have a
Module argument. To improve startup performance, avoid any heavy initializations in the constructor.
A service not going to be overridden does not need to be registered in plugin.xml (see Declaring a Service). Instead, annotate service class with
@Service. The service instance will be created in scope according to the caller (see Retrieving a Service).
Service class must be
Constructor injection is not supported (since it is deprecated).
If service is a PersistentStateComponent, roaming must be disabled (
roamingType = RoamingType.DISABLED).
See Project Level Service below for a sample.
Declaring a Service
To register a non- Light Service, distinct extension points are provided for each type:
com.intellij.applicationService- application level service
com.intellij.projectService- project level service
com.intellij.moduleService- module level service (not recommended, see Note above)
To expose service API, create separate class for
serviceInterface and extend it in corresponding class registered in
serviceInterface isn't specified, it's supposed to have the same value as
To provide custom implementation for test/headless environment, specify
Retrieving a Service
Getting service doesn't need a read action and can be performed from any thread. If service is requested from several threads, it will be initialized in the first thread, and other threads will be blocked until service is fully initialized.
Project Service Sample
This minimal sample shows Light Service
ProjectService interacting with another project level service
AnotherService (not shown here).
To clarify how to use services, consider the maxOpenProjects sample plugin available in the code samples.
This plugin has an application service counting the number of currently opened projects in the IDE. If this number exceeds the maximum number of simultaneously opened projects allowed by the plugin (3), it displays a warning message.
See Code Samples on how to set up and run the plugin.