ObservableList in JavaFX

Fri, Dec 15, 2023 2-minute read

Here is example JavaFX application that demonstrates the use of an ObservableList. This application will include a simple user interface where items can be added to or removed from the list, and the changes will be reflected in real-time on the UI.

ObservableList Example

Here’s a basic outline of the application:

Main Application Class: This class extends Application and sets up the primary stage.
UI Elements: Includes a ListView to display the ObservableList, and buttons to add or remove items.
ObservableList: A list that automatically updates the ListView when items are added or removed.

Example JavaFX Application with ObservableList

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ObservableListExample extends Application {

    private ObservableList<String> items;

    @Override
    public void start(Stage primaryStage) {
        // Initialize the ObservableList
        items = FXCollections.observableArrayList();

        // Create a ListView to display the items
        ListView<String> listView = new ListView<>(items);

        // Buttons to add and remove items
        Button addButton = new Button("Add Item");
        Button removeButton = new Button("Remove Selected Item");

        // Event Handler for addButton
        addButton.setOnAction(e -> items.add("New Item " + (items.size() + 1)));

        // Event Handler for removeButton
        removeButton.setOnAction(e -> {
            int selectedIndex = listView.getSelectionModel().getSelectedIndex();
            if (selectedIndex != -1) {
                items.remove(selectedIndex);
            }
        });

        // Layout
        VBox layout = new VBox(10, listView, addButton, removeButton);
        layout.setPadding(new javafx.geometry.Insets(10));

        // Set the scene and stage
        Scene scene = new Scene(layout, 300, 250);
        primaryStage.setTitle("ObservableList Example");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

How to Run:

Create a JavaFX Project: Set up a JavaFX project in your IDE.
Add the Code: Copy the above code into a new class file.
Run the Application: Compile and run the application.

Explanation:

The ObservableList is linked to the ListView. Any changes to the list (additions or removals) will automatically update the ListView.
The addButton adds a new item to the list.
The removeButton removes the selected item from the list.

This example is a simple demonstration of how an ObservableList works in JavaFX. You can expand on this by adding more complex data types and additional UI elements.

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