Settings Tutorial

As discussed in the Settings Guide, plugins can add Settings to IntelliJ Platform-based IDEs. The IDE displays the Settings in response to a user choosing Settings. Custom Settings are displayed and function like those native to the IDE.

Overview of Custom Settings Implementation

Using the SDK code sample settings, this tutorial illustrates the steps to creating custom application-level settings. Many IntelliJ Platform Settings implementations use fewer classes, but the settings code sample factors the functionality into three classes for clarity:

The AppSettingsConfigurable is analogous to a Controller in the MVC model – it interacts with the other two Settings classes and the IntelliJ Platform,
The AppSettings is like a Model because it stores the Settings persistently,
The AppSettingsComponent is similar to a View because it displays and captures edits to the values of the Settings.

The structure of the implementation is the same for Project Settings, but there are minor differences in the Configurable implementation and extension point (EP) declaration.

The `AppSettings` Class

The AppSettings class persistently stores the custom Settings. It is based on the IntelliJ Platform Persistence Model.

Declaring `AppSettings`

Given a Light Service is not used, the persistent data class must be declared as a Service EP in the plugin.xml file. If these were Project Settings, the com.intellij.projectService extension point would be used. However, because these are Application Settings, the com.intellij.applicationService extension point is used with the fully qualified name (FQN) of the implementation class:

<extensions defaultExtensionNs="com.intellij">
  <applicationService
      serviceImplementation="org.intellij.sdk.settings.AppSettings"/>
</extensions>

Creating the `AppSettings` Implementation

As discussed in Implementing the PersistentStateComponent Interface, AppSettings uses the pattern of implementing PersistentStateComponent parameterized by a separate state class:

@State(
    name = "org.intellij.sdk.settings.AppSettings",
    storages = @Storage("SdkSettingsPlugin.xml")
)
final class AppSettings
    implements PersistentStateComponent<AppSettings.State> {

  static class State {
    @NonNls
    public String userId = "John Smith";
    public boolean ideaStatus = false;
  }

  private State myState = new State();

  static AppSettings getInstance() {
    return ApplicationManager.getApplication()
        .getService(AppSettings.class);
  }

  @Override
  public State getState() {
    return myState;
  }

  @Override
  public void loadState(@NotNull State state) {
    myState = state;
  }

}

`@Storage` Annotation

The @State annotation, located above the class declaration, defines the data storage location. For AppSettings, the data name parameter is the FQN of the class. Using FQN is the best practice to follow and is required if custom data gets stored in the standard project or workspace files.

The storages parameter uses the @Storage annotation to define a custom filename for the AppSettings data. In this case, the file is located in the options directory of the configuration directory for the IDE.

Persistent State Class

The AppSettings implementation contains an inner state class with two public fields: a String and a boolean. Conceptually, these fields hold the name of a user and whether that person is an IntelliJ IDEA user, respectively. See Implementing the State Class for more information about how PersistentStateComponent serializes public fields.

`AppSettings` Methods

The fields are so limited and straightforward for this class that encapsulation is not used for simplicity. All that is needed for functionality is to override the two methods called by the IntelliJ Platform when a new component state is loaded (PersistentStateComponent.loadState()), and when a state is saved (PersistentStateComponent.getState()). See PersistentStateComponent for more information about these methods.

One static convenience method has been added – AppSettings.getInstance() – which allows AppSettingsConfigurable to easily acquire a reference to AppSetting.

The `AppSettingsComponent` Class

The role of the AppSettingsComponent is to provide a JPanel for the custom Settings to the IDE Settings Dialog. The AppSettingsComponent has-a JPanel, and is responsible for its lifetime. The AppSettingsComponent is instantiated by AppSettingsConfigurable.

Creating the `AppSettingsComponent` Implementation

The AppSettingsComponent defines a JPanel containing a JBTextField and a JBCheckBox to hold and display the data that maps to the data fields of AppSettings.State:

/**
 * Supports creating and managing a {@link JPanel} for the Settings Dialog.
 */
public class AppSettingsComponent {

  private final JPanel myMainPanel;
  private final JBTextField myUserNameText = new JBTextField();
  private final JBCheckBox myIdeaUserStatus = new JBCheckBox("IntelliJ IDEA user");

  public AppSettingsComponent() {
    myMainPanel = FormBuilder.createFormBuilder()
        .addLabeledComponent(new JBLabel("User name:"), myUserNameText, 1, false)
        .addComponent(myIdeaUserStatus, 1)
        .addComponentFillVertically(new JPanel(), 0)
        .getPanel();
  }

  public JPanel getPanel() {
    return myMainPanel;
  }

  public JComponent getPreferredFocusedComponent() {
    return myUserNameText;
  }

  @NotNull
  public String getUserNameText() {
    return myUserNameText.getText();
  }

  public void setUserNameText(@NotNull String newText) {
    myUserNameText.setText(newText);
  }

  public boolean getIdeaUserStatus() {
    return myIdeaUserStatus.isSelected();
  }

  public void setIdeaUserStatus(boolean newStatus) {
    myIdeaUserStatus.setSelected(newStatus);
  }

}

`AppSettingsComponent` Methods

The constructor builds the JPanel using the convenient FormBuilder and saves a reference to the JPanel. The rest of the class are simple accessors and mutators to encapsulate the UI components used on the JPanel.

The `AppSettingsConfigurable` Class

The methods of AppSettingsConfigurable are called by the IntelliJ Platform, and AppSettingsConfigurable in turn interacts with AppSettingsComponent and AppSettings.

Declaring the `AppSettingsConfigurable`

As described in Declaring Application Settings, the com.intellij.applicationConfigurable is used as the EP. An explanation of this declaration can be found in Declaring Application Settings:

<extensions defaultExtensionNs="com.intellij">
  <applicationConfigurable
      parentId="tools"
      instance="org.intellij.sdk.settings.AppSettingsConfigurable"
      id="org.intellij.sdk.settings.AppSettingsConfigurable"
      displayName="SDK: Application Settings Example"/>
</extensions>

Creating the `AppSettingsConfigurable` Implementation

The AppSettingsConfigurable class implements Configurable. The class has one field to hold a reference to the AppSettingsComponent.

/**
 * Provides controller functionality for application settings.
 */
final class AppSettingsConfigurable implements Configurable {

  private AppSettingsComponent mySettingsComponent;

  // A default constructor with no arguments is required because
  // this implementation is registered as an applicationConfigurable

  @Nls(capitalization = Nls.Capitalization.Title)
  @Override
  public String getDisplayName() {
    return "SDK: Application Settings Example";
  }

  @Override
  public JComponent getPreferredFocusedComponent() {
    return mySettingsComponent.getPreferredFocusedComponent();
  }

  @Nullable
  @Override
  public JComponent createComponent() {
    mySettingsComponent = new AppSettingsComponent();
    return mySettingsComponent.getPanel();
  }

  @Override
  public boolean isModified() {
    AppSettings.State state =
        Objects.requireNonNull(AppSettings.getInstance().getState());
    return !mySettingsComponent.getUserNameText().equals(state.userId) ||
        mySettingsComponent.getIdeaUserStatus() != state.ideaStatus;
  }

  @Override
  public void apply() {
    AppSettings.State state =
        Objects.requireNonNull(AppSettings.getInstance().getState());
    state.userId = mySettingsComponent.getUserNameText();
    state.ideaStatus = mySettingsComponent.getIdeaUserStatus();
  }

  @Override
  public void reset() {
    AppSettings.State state =
        Objects.requireNonNull(AppSettings.getInstance().getState());
    mySettingsComponent.setUserNameText(state.userId);
    mySettingsComponent.setIdeaUserStatus(state.ideaStatus);
  }

  @Override
  public void disposeUIResources() {
    mySettingsComponent = null;
  }

}

`AppSettingsConfigurable` Methods

All the methods in this class are overrides of the methods in the Configurable interface. Readers are encouraged to review the Javadoc comments for the Configurable methods. Also, review notes about IntelliJ Platform Interactions with Configurable methods.

Testing the Custom Settings Plugin

After performing the steps described above, compile and run the plugin in a Development Instance to see the custom Settings available in the Settings Dialog. Open the IDE Settings by selecting Settings | Tools | SDK: Application Settings Example. The settings are preloaded with the default values:

Now edit the settings values to "John Doe" and click the checkbox. Click the OK button to close the Settings dialog and save the changes. Exit the Development Instance.

Open the file code_samples/settings/build/idea-sandbox/config/options/SdkSettingsPlugin.xml to see the Settings persistently stored.

19 March 2025

Settings Tutorial

Overview of Custom Settings Implementation

The AppSettings Class

Declaring AppSettings

Creating the AppSettings Implementation

@Storage Annotation

Persistent State Class

AppSettings Methods

The AppSettingsComponent Class

Creating the AppSettingsComponent Implementation

AppSettingsComponent Methods

The AppSettingsConfigurable Class

Declaring the AppSettingsConfigurable

Creating the AppSettingsConfigurable Implementation

AppSettingsConfigurable Methods