# Maximum Open Projects Sample [![JetBrains IntelliJ Platform SDK Docs](https://jb.gg/badges/docs.svg)][docs] *Reference: [Plugin Services in IntelliJ SDK Docs][docs:plugin_services]* ## Quickstart Maximum Open Projects Sample implements a `ProjectManagerListener` with two methods applied to check if the current projects have been opened or closed. Each method refers to the `ProjectCountingService` service registered as an `applicationService` extension point. It provides methods to increase and decrease the global counter of the currently opened projects in the IDE. After opening each one, a message dialog is presented to the user with the current number. ### Extension Points | Name | Implementation | Extension Point Class | | --------------------------------- | ----------------------------------------------------- | --------------------- | | `com.intellij.applicationService` | [ProjectCountingService][file:ProjectCountingService] | n/a | *Reference: [Plugin Extension Points in IntelliJ SDK Docs][docs:ep]* ### Application Listeners | Name | Implementation | Listener Class | | -------- | --------------------------------------------------------- | ------------------------ | | listener | [ProjectOpenCloseListener][file:ProjectOpenCloseListener] | `ProjectManagerListener` | *Reference: [Plugin Listeners in IntelliJ SDK Docs][docs:listeners]* [docs]: https://plugins.jetbrains.com/docs/intellij/ [docs:plugin_services]: https://plugins.jetbrains.com/docs/intellij/plugin-services.html [docs:ep]: https://plugins.jetbrains.com/docs/intellij/plugin-extensions.html [docs:listeners]: https://plugins.jetbrains.com/docs/intellij/plugin-listeners.html [file:ProjectCountingService]: ./src/main/java/org/intellij/sdk/maxOpenProjects/ProjectCountingService.java [file:ProjectOpenCloseListener]: ./src/main/java/org/intellij/sdk/maxOpenProjects/ProjectOpenCloseListener.java