JavaFX Properties and Events Sample

JavaFXPropertiesSample.java

// Counter.java class

import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;

/**
 *
 * @author omers
 */
public class Counter {
    
    private IntegerProperty value = new SimpleIntegerProperty(this, "value");
    
    public final IntegerProperty valueProperty() { return value; }
    
    public final int getValue() { return valueProperty().get(); }
    
    public final void setValue(int i) { valueProperty().set(i); }
    
}


// Main.java class

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @author omers
 */
public class Main extends Application{
    
    public static void main(String [] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        // Create the counter object
        final Counter counter = new Counter();
        
        // Create a button to increment the counter value
        final Button incrementButton = new Button("Increment");
        incrementButton.setOnAction((ActionEvent event) -> { // Using lambda expression.
            counter.setValue(counter.getValue() + 1);
        });
        
        // Create the label for displaying count
        final Label countLabel = new Label("Count : ");
        
        // I attach a listener to the value property, and update the
        // label whenever it changes.
        counter.valueProperty().addListener(new ChangeListener<Number>() {
            @Override
            public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
                countLabel.setText("Count : " + newValue.intValue());
            }
        });
        
        VBox vBox = new VBox(5);
        vBox.setPadding(new Insets(12));
        vBox.getChildren().addAll(countLabel, incrementButton);
        primaryStage.setScene(new Scene(vBox));
        primaryStage.show();
    }
    
}