ChoiceBox: freeze when removing selected item from another ChoiceBox - javafx

Question

I want to use two ChoiceBoxes offering the same select items with the exception of the one selected by the other. However, after selecting options a few times, the entire java process becomes unresponsive.
Update: the issue does not occur if I use ComboBox instead of ChoiceBox. However, an explanation for why it happens would be interesting.
I have two ChoiceBoxes
#FXML private ChoiceBox<String> firstCB;
#FXML private ChoiceBox<String> secondCB;
that initially have the same selection options
firstCB.getItems().addAll(Charset.availableCharsets().keySet());
secondCB.getItems().addAll(Charset.availableCharsets().keySet());
and event listeners to remove the new selection from the other ChoiceBox's options and make the old option available again
firstCB.getSelectionModel().selectedItemProperty()
.addListener((observable, oldVal, newVal) -> {
secondCB.getItems().remove(newVal);
secondCB.getItems().add(oldVal);
});
the equivalent Swing code with JComboBoxes and the following event handler works
firstCB.addItemListener(itemEvent -> {
if (itemEvent.getStateChange() == ItemEvent.DESELECTED) {
secondCB.addItem((String) itemEvent.getItem());
} else if (itemEvent.getStateChange() == ItemEvent.SELECTED) {
secondCB.removeItem(itemEvent.getItem());
}
});
Full code:
class test.Main
public class Main extends Application {
private Parent rootPane;
#Override
public void start(Stage arg0) throws Exception {
Scene scene = new Scene(rootPane);
arg0.setScene(scene);
arg0.show();
}
#Override
public void init() throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("/main.fxml"));
rootPane = loader.load();
loader.<View>getController().init();
}
public static void main(String[] args) {
launch(args);
}
}
class test.View
public class View {
#FXML
private ChoiceBox<String> firstCB;
#FXML
private ChoiceBox<String> secondCB;
public void init() {
firstCB.getItems().addAll(Charset.availableCharsets().keySet());
secondCB.getItems().addAll(Charset.availableCharsets().keySet());
firstCB.getSelectionModel().selectedItemProperty()
.addListener((observable, oldVal, newVal) -> {
System.out.printf("[%s]firstCB selection changed%n", Thread.currentThread().getName());
secondCB.getItems().remove(newVal);
secondCB.getItems().add(oldVal);
});
// removing one of the event listeners doesn't help
secondCB.getSelectionModel().selectedItemProperty()
.addListener((observable, oldVal, newVal) -> {
System.out.printf("[%s]secondCB selection changed%n", Thread.currentThread().getName());
firstCB.getItems().remove(newVal);
firstCB.getItems().add(oldVal);
});
}
}
main.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<Pane fx:id="rootPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="90.0" prefWidth="180.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="test.View">
<children>
<ChoiceBox fx:id="firstCB" layoutX="14.0" layoutY="14.0" prefWidth="150.0" />
<ChoiceBox fx:id="secondCB" layoutX="14.0" layoutY="52.0" prefWidth="150.0" />
</children>
</Pane>

Answer 1

try this, it works fine for me
firstComboBox.valueProperty().addListener((obs, oldV, newV) -> {
secondComboBox.getItems().remove(newV);
if(oldV!= null) secondComboBox.getItems().add(oldV);
});
secondComboBox.valueProperty().addListener((obs, oldV, newV) -> {
firstComboBox.getItems().remove(newV);
if(oldV!= null) firstComboBox.getItems().add(oldV);
});
or other not best solution with observable and filtered list
public class Controller implements Initializable{
public ComboBox<String> firstComboBox;
public ComboBox<String> secondComboBox;
#Override
public void initialize(URL location, ResourceBundle resources) {
ObservableList<String> list = FXCollections.observableArrayList();
list.addAll("one", "two", "three", "four", "five");
firstComboBox.getItems().addAll(list);
secondComboBox.getItems().addAll(list);
firstComboBox.valueProperty().addListener(c -> refreshList(list, secondComboBox, firstComboBox));
secondComboBox.valueProperty().addListener(c -> refreshList(list, firstComboBox, secondComboBox));
}
private void refreshList(ObservableList<String> list, ComboBox<String> choiceBox, ComboBox<String> choiceBox2) {
String tmp = choiceBox.getValue();
FilteredList<String> filteredList = new FilteredList<>(list, string -> !string.equals(choiceBox2.getValue()));
choiceBox.setItems(filteredList);
choiceBox.setValue(tmp);
}