gistfile1.java

package com.dooapp.FXBinding.model;

import javafx.beans.binding.DoubleBinding;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.chart.XYChart;

/**
 * A simple demo class
 * Created at 20/06/13 14:44.<br>
 *
 * @author Christophe DUFOUR
 */
public class Foo {
    /**
     * A list of double values
     */
    private ObservableList<XYChart.Data<Number, Number>> values = FXCollections.observableArrayList(new XYChart.Data<Number, Number>(0.3d, 0.3d), new XYChart.Data<Number, Number>(0.1d, 0.1d), new XYChart.Data<Number, Number>(0.2d, 0.2d));
    /**
     * A list of double values
     */
    public ObservableList<XYChart.Data<Number, Number>> values() {
        return values;
    }
    /**
     * the average value of all XValue of Data in values
     *
     * @see #values()
     */
    private DoubleBinding averageBinding = new DoubleBinding() {
        {
            //call #computeValue every time #values() changes
            super.bind(values());
        }
        @Override
        protected double computeValue() {
            double result = 0;
            if (values().isEmpty()) {
                return result;
            }
            for (XYChart.Data<Number, Number> d : values()) {
                result += d.getXValue().doubleValue();
            }
            return result / values().size();
        }
    };
    /**
     * the average value of all double in values
     *
     * @see #values()
     */
    public DoubleBinding averageBinding() {
        return averageBinding;
    }
    /**
     * Just a main to show a demo
     *
     * @param args args
     */
    public static void main(String[] args) {
        Foo foo = new Foo();
        System.out.println(foo.averageBinding().get()); //Should print 0.2
        foo.values().add(new XYChart.Data<Number, Number>(-3d, -3d));
        System.out.println(foo.averageBinding().get()); //Should print -0.6
        foo.values().get(0).setXValue(30d);
        System.out.println(foo.averageBinding().get()); //Should not print -0.6
    }
}