JavaFX Properties Examples

A simple JavaFX tutorial through simple snippets.

Example 1: Properties

Here are the code:

Step 1: Create Project

1. Open your favorite Java IDE.
2. In the menu go to File --> Create New Project.

Step 2: Dependencies

No dependencies are needed for this project.

Step 3: Write Code

Our code will comprise the following java files:

• PropertyExample.java

1. In your editor or IDE, create a file known as PropertyExample.java.
2. Then add the following code:

(a). PropertyExample.java

Go ahead and add the following imports:

import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.ReadOnlyDoubleProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

We will need to extend our class using the extend keyword. By doing that our class can make use of inheritance to derive properties and functions defined in the parent class.

public class PropertyExample extends Application {

Our class will have the following methods:

• void main(String[] args)
• void start(Stage primaryStage)
• void changed(ObservableValue<? extends Number> observableValue, Number oldVal, Number newVal)

First of all we will need a main method. This is the entry point of our Java application.

    public static void main(String[] args) {

In this particular class we will be overriding our void changed(ObservableValue<? extends Number> observableValue, Number oldVal, Number newVal) method.
Prepend the code>@Override</code modifier to your method. Then add implementation code as follows:

            @Override
            public void changed(ObservableValue<? extends Number> observableValue, Number oldVal, Number newVal) {
                System.out.println("widthProperty changed from " + oldVal.doubleValue() + " to " + newVal.doubleValue());
            }

Here is the full code:

package com.jenkov.javafx.properties;

import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.ReadOnlyDoubleProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class PropertyExample extends Application {

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

    public void start(Stage primaryStage) {

        Pane pane = new Pane();

        ReadOnlyDoubleProperty widthProperty = pane.widthProperty();
        widthProperty.addListener( new ChangeListener<Number> (){
            @Override
            public void changed(ObservableValue<? extends Number> observableValue, Number oldVal, Number newVal) {
                System.out.println("widthProperty changed from " + oldVal.doubleValue() + " to " + newVal.doubleValue());
            }
        });

        DoubleProperty prefWidthProperty = pane.prefWidthProperty();
        prefWidthProperty.addListener( (ObservableValue<? extends Number> prop, Number oldVal, Number newVal) -> {
            System.out.println("prefWidthProperty changed from " + oldVal.doubleValue() + " to " + newVal.doubleValue());
        });

        prefWidthProperty.set(123);

        Scene scene = new Scene(pane, 1024, 800, true);
        primaryStage.setScene(scene);
        primaryStage.setTitle("2D Example");

        primaryStage.show();
    }
}

Download

Download the code using the below links: