Developing IntelliJ IDEA Plugins: A Step‑by‑Step Guide

Before starting, install a Java SDK, be comfortable with Java (Kotlin is recommended), and download the IntelliJ IDEA Community edition from https://www.jetbrains.com/idea/download . Clone the IDEA community source code from https://github.com/JetBrains/intellij-community and read the official SDK documentation at http://www.jetbrains.org/intellij/sdk/docs .

Step 1 – Create a new plugin project

Select IntelliJ Platform Plugin as the project type and proceed through the wizard.

After the project is created, add a new Action class in a package of your choice.

Fill in the required fields in the plugin.xml (Action ID, Class Name, Name, Description, Groups). The IDE will automatically insert the new action.

<actions>
    <!-- Add your actions here -->
    <action id="com.example.MyAction" class="com.example.MyAction" text="My Action" description="My custom action">
        <add-to-group group-id="ToolsMenu" anchor="last"/>
    </action>
</actions>

The anchor attribute determines the action’s position in the menu (first, last, before, after).

Step 2 – Implement the action

@Override
public void actionPerformed(AnActionEvent e) {
    Project project = e.getProject();
    Messages.showMessageDialog(project, "helloworld", "mytitle", Messages.getInformationIcon());
}

Run the plugin; a new IDEA window opens, and selecting the action shows a HelloWorld dialog.

Advanced Topics

1. UI thread handling : Use ApplicationManager.getApplication().invokeLater(...) to update UI from background threads.

ApplicationManager.getApplication().invokeLater(new Runnable() {
    @Override
    public void run() {
        // update UI
    }
});

2. Starting background tasks : Use ProgressManager.getInstance().run(...) or BackgroundTaskQueue to execute long‑running work.

new BackgroundTaskQueue(project, "my-task-name").run(new MyTask());

3. Virtual File System (VFS) : Provides a unified API for files regardless of location (disk, archive, HTTP, git). It tracks changes and allows attaching persistent data.

4. Program Structure Interface (PSI) : Parses files and creates a rich syntax/semantic model used by many IDE features. See the official PSI documentation for details.

5. UI components : IntelliJ provides custom Swing components (tool windows, dialogs, popups, notifications, file choosers, editor components, list/tree controls) that keep plugins visually consistent with the IDE.

Refer to the official UI components guide for more information.

Conclusion

VFS and PSI are core modules for plugin development. Studying open‑source plugins and the official SDK documentation will greatly accelerate learning.