ChoiceBox

A ChoiceBox is a dropdown list that lets the user select one option from a list.

Example:

Select language → Java / Python / C++

👉 Only one value can be selected at a time.

1️⃣ FXML: ChoiceBox with Label

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.ChoiceBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.VBox?>

<VBox spacing="15" alignment="CENTER" xmlns="http://javafx.com/javafx/17"
      xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.ChoiceBoxController">

    <Label text="Select your favorite fruit:"/>
    
    <ChoiceBox fx:id="fruitChoiceBox" onAction="#handleChoiceBoxAction"/>
    
    <Label fx:id="selectionLabel" text="Your selection will appear here."/>
    
</VBox>

Explanation:

• fx:id="fruitChoiceBox" → lets the controller access the ChoiceBox.
• onAction="#handleChoiceBoxAction" → calls a method whenever the selection changes.
• selectionLabel → shows the currently selected value.

2️⃣ Controller: Populate and Handle ChoiceBox

package com.example;

import javafx.collections.FXCollections;
import javafx.fxml.FXML;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.Label;

public class ChoiceBoxController {

    @FXML
    private ChoiceBox<String> fruitChoiceBox;

    @FXML
    private Label selectionLabel;

    // Initialize method is called automatically after FXML loads
    @FXML
    private void initialize() {
        // Populate ChoiceBox items
        fruitChoiceBox.setItems(FXCollections.observableArrayList(
                "Apple", "Banana", "Orange", "Mango", "Grapes"
        ));
        // Set default value
        fruitChoiceBox.setValue("Apple");
        // Show default value in label
        selectionLabel.setText("Default selection: " + fruitChoiceBox.getValue());
    }

    // Called when user changes selection
    @FXML
    private void handleChoiceBoxAction() {
        String selectedFruit = fruitChoiceBox.getValue();
        selectionLabel.setText("You selected: " + selectedFruit);
    }
}

Explanation:

1. initialize() → populate items and set a default value.
2. getValue() → get the currently selected item.
3. handleChoiceBoxAction() → dynamically updates the selectionLabel.

3️⃣ Main Class: Load FXML

package com.example;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class MainApp extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("choicebox_layout.fxml"));
        Scene scene = new Scene(loader.load(), 350, 200);
        stage.setScene(scene);
        stage.setTitle("ChoiceBox Example");
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}

✅ Extra Notes for Learning ChoiceBox:

1. Single selection only – if you need multiple selections, use ListView or ComboBox with editable option.
2. Default value is optional – if not set, the ChoiceBox is empty initially.
3. Dynamic reactions – you can trigger any code in handleChoiceBoxAction() like changing colors, updating other UI elements, or even enabling buttons.