I just stumbled over an error in my ListView and found out, that the selectionModel.getSelectedItems().size() is always 1, if I selected an item, and then clear all items (or remove the selected one).

This is confusing, at least for me. I expected the size() to be 0, as it is the same state as before, if nothing was selected.

Code sample: Add 2 items, select the FIRST one, click the clear button. getSelectedItems().size() is 1 then. Strangely, if you selected the second item, the size() is 0.

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.layout.VBoxBuilder;
import javafx.stage.Stage;

public class TestApp2 extends Application {
    public static void main(String[] args) {
        Application.launch();
    }


    private ObservableList<String> items = FXCollections.observableArrayList();

    @Override
    public void start(Stage stage) throws Exception {
        final ListView<String> listView = new ListView<String>();
        listView.setItems(items);

        System.out.println(listView.getSelectionModel().getSelectedItems().size());
        Button buttonAdd = new Button("Add");
        buttonAdd.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent actionEvent) {
                items.add("Test");
            }
        });
        Button buttonClear = new Button("Clear");
        buttonClear.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent actionEvent) {
                items.clear();
                System.out.println(listView.getSelectionModel().getSelectedItems().size());
            }
        });

        Scene scene = new Scene(VBoxBuilder.create().children(listView, buttonAdd, buttonClear).build());
        stage.setScene(scene);
        stage.show();
    }
}