ChoiceBox Overview

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Updated on July 03, 2019

The

ChoiceBox

class is used to create a control which presents the user with a few choices to pick from a drop-down list. The user is only allowed to pick one of the options. When the drop-down list is not showing then the currently selected option is the only one visible. It is possible to set the

ChoiceBox


   Import Statement  

import javafx.scene.control.ChoiceBox;


   Constructors  

The
ChoiceBox


//Create an empty ChoiceBox
ChoiceBox choices = new ChoiceBox();
//Create a ChoiceBox using an observable list collection
ChoiceBox cboices = new ChoiceBox(FXCollections.observableArrayList("Apple", "Banana", "Orange", "Peach", "Pear", "Strawberry"));


   Useful Methods  

If you choose to create an empty
ChoiceBox
 items can be added later using the setItems


choices.setItems(FXCollections.observableArrayList("Apple", "Banana", "Orange", "Peach", "Pear", "Strawberry"));



And, if you want to find out what items are in a
ChoiceBox
 you can use the getItems


List options = choices.getItems();



To pick an option to be currently selected use the
setValue


choices.setValue("First");



To get the value of the option currently selected use the corresponding
getValue
 method and assign it to a String


String option = choices.getValue().toString();

Event Handling

In order to listen to events for a

ChoiceBox

object, the

SelectionModel

is used. The

ChoiceBox

uses the

SingleSelectionModel

class which only permits one option to be chosen at a time. The

selectedIndexProperty

method allows us to add a

ChangeListener


final List options = choices.getItems();
choices.getSelectionModel().selectedIndexProperty().addListener(new ChangeListener() {
 @Override public void changed(ObservableValue ov, Number oldSelected, Number newSelected) {
 
 System.out.println("Old Selected Option: " + options.get(oldSelected.intValue()));
 System.out.println("New Selected Option: " +options.get(newSelected.intValue()));
 
 } 
 });

It's also possible to show or hide the list of options without the user having to click on the

ChoiceBox

object by using the

show

and

hide

methods. In the code below a Button object is used to call the show method of a

ChoiceBox

object when the

Button


//Use a stackpane for a simple layout of the controls
StackPane root = new StackPane();
//Create Button to show the options in the ChoiceBox
Button showOptionButton = new Button("Show Options");
root.getChildren().add(showOptionButton);
root.setAlignment(showOptionButton, Pos.TOP_CENTER);
//Create the ChoiceBox with a few options
final ChoiceBox choices = new ChoiceBox(FXCollections.observableArrayList("Apple", "Banana", "Orange", "Peach", "Pear", "Strawberry"));
root.getChildren().add(choices);
//Use the ActionEvent to call the ChoiceBox show method
showOptionButton.setOnAction(new EventHandler() {
 @Override public void handle(ActionEvent e) {
 choices.show();
 }
});
//Set the Scene and put the Stage into motion..
Scene scene = new Scene(root, 300, 250);
primaryStage.setScene(scene);
primaryStage.show();

To find out about other JavaFX controls, have a look at JavaFX User Interface Controls.