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  1. JDK
  2. JDK-8120351

ListView.getSelectionModel().getSelectedItems() ObservableList: no remove notification

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    • Bug
    • Status: Resolved
    • P4
    • Resolution: Fixed
    • 8
    • 8
    • javafx

    Description

      When attaching Listeners to the getSelectedItems() ObservableList, only additions to the selected items (ie. selecting a new item) are notified, never removals (ie. deselecting an item or changing from an item to another should throw a remove for the not-anymore-selected item, and then an add for the new one).
      The following code illustrates the problem nicely:

      import javafx.application.Application;
      import javafx.collections.FXCollections;
      import javafx.collections.ListChangeListener;
      import javafx.collections.ObservableList;
      import javafx.geometry.Rectangle2D;
      import javafx.scene.Scene;
      import javafx.scene.control.ListView;
      import javafx.scene.control.SelectionMode;
      import javafx.scene.layout.StackPane;
      import javafx.scene.paint.Color;
      import javafx.stage.Screen;
      import javafx.stage.Stage;

      public final class selectedItemsTest extends Application {
      public static void main(final String[] args) {
      // Launch the JavaFX application: do initialization and call start()
      // when ready.
      Application.launch(args);
      }

      @Override
      public void start(final Stage primaryStage) throws Exception {
      final StackPane stack = new StackPane();
      final Rectangle2D screen = Screen.getPrimary().getVisualBounds();
      final Scene rootScene = new Scene(stack, screen.getWidth(), screen.getHeight(), Color.GRAY);

      final ObservableList<String> inputStreams = FXCollections.observableArrayList("1", "2", "3", "4", "5");

      final ListView<String> streams = new ListView<>();
      stack.getChildren().add(streams);

      streams.setItems(inputStreams);
      streams.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);

      final ObservableList<String> selectedInputStreams = streams.getSelectionModel().getSelectedItems();

      selectedInputStreams.addListener(new ListChangeListener<String>() {
      @Override
      public void onChanged(final Change<? extends String> change) {
      while (change.next()) {
      for (final String removed : change.getRemoved()) {
      System.out.println("Removed: " + removed);
      }

      for (final String added : change.getAddedSubList()) {
      System.out.println("Added: " + added);
      }
      }

      if (!change.getList().isEmpty()) {
      for (final String inList : change.getList()) {
      System.out.println("In list currently: " + inList);
      }
      }
      }
      });

      primaryStage.setTitle("TEST");
      primaryStage.setScene(rootScene);

      primaryStage.show();
      }
      }

      You'll notice that the list itself (getList()) is alwasy correct and reflects removals correctly, they just never get notified to the listeners, which makes it impossible to update other data-structures correctly from a listener.
      The temporary workaround I'm using is to clear() and then addAll(change.getList()), since the content of the list is, as said above, always accurate.
      This might be partially related to RT-24367, as in making getSelectedItems() a separate ObservableList in its own right from the getItems() one would solve RT-24367, and adding a Listener to remove items removed from getItems() from the getSelectedItems() list too, and add/remove from getSelectedItems() based on the UI selection, would keep behavior consistent and fix the above.
      I'm on JDK 1.8.0-ea-b102, I hope to have selected the right version. ;-)

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            jgiles Jonathan Giles
            duke J. Duke (Inactive)
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              Created:
              Updated:
              Resolved:
              Imported: