Comprehensive Guide to Developing IntelliJ IDEA Plugins: Setup, Actions, UI Thread, Background Tasks, VFS, PSI, and UI Components

Author : Gu Xuan Yu – Android developer at Tongtian Tower Technology Open Group.

Before starting development, install Java SDK, be proficient in Java (preferably Kotlin), and download the IntelliJ IDEA Community edition (required for Android Studio plugin development). Also clone the IDEA community source code and review the official SDK documentation.

Getting Started

Create a new plugin project by selecting IntelliJ Platform Plugin in the wizard and follow the steps.

1. Create a New Action

In the src package, add a new Action class and fill in the required fields in the plugin.xml wizard:

Action ID – unique identifier, usually package.ClassName

Class Name – name of the Action class

Name – text displayed in the UI

Description – brief description

Groups – the group where the action will appear

After confirming, the plugin.xml entry is automatically added:

<actions>
  <!-- Add your actions here -->
  <action id="xxx" class="xxx" text="xxx"/>
</actions>

The anchor attribute determines the action's position within the group (first, last, before, after).

2. Implement the Action Logic

Override public void actionPerformed(AnActionEvent e) and, for a simple Hello World example, show a message dialog:

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

Run the plugin; the new action appears in the IDE and displays the dialog when invoked.

3. Advanced Topics

Event Thread UI Updates

UI updates must occur on the event thread. Use ApplicationManager.getApplication().invokeLater(...) to schedule UI changes after background work.

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

Starting Background Tasks

Use ProgressManager to run long‑running operations without blocking the UI:

ProgressManager.getInstance().run(new Runnable() {
    public void run() {
        // background work
    }
});

Progress Bar Tasks

Create a class extending Task.Backgroundable and execute it via BackgroundTaskQueue :

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

Virtual File System (VFS)

VFS provides a unified API for handling files regardless of their physical location. It supports refreshing, retrieving VirtualFile instances, and attaching persistent data.

Program Structure Interface (PSI)

PSI represents the parsed structure of files, enabling syntax and semantic analysis. It is essential for language‑specific features.

UI Components

The IntelliJ platform offers many custom Swing components such as tool windows, dialogs, popups, notifications, file/class choosers, editor components, and list/tree controls, ensuring a consistent look and feel.

Conclusion

VFS and PSI are core modules for plugin development. Reviewing open‑source plugins and the official documentation helps deepen understanding.

References

AndroidStudio plugin development (HelloWorld) by huachao1001 – https://blog.csdn.net/huachao1001/article/details/53856916

IntelliJ IDEA SDK documentation – http://www.jetbrains.org/intellij/sdk/docs

IntelliJ Community source code – https://github.com/JetBrains/intellij-community