How do I listen for bean’s property change event?

In this example we’ll listen to bean’s property change event. We create a small bean named MyBean, adds attributes and getter/setter. We want to know or to get notified when the bean property name is changed.

First we need the add a PropertyChangeSupport field to the bean, with this object we will fire the property change event. When we need to listen for the change we have to create an implementation of a PropertyChangeListener. In this example we’ll just use the MyBean class as the listener.

The PropertyChangeListener has a method called propertyChange and inside this method we’ll implement the code to get the event fired by the PropertyChangeSupport.

package org.kodejava.bean;

import java.beans.PropertyChangeSupport;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeEvent;

public class MyBean implements PropertyChangeListener, Serializable {
    private Long id;
    private String name;

    private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);

    public MyBean() {

     * This method gets called when a bound property is changed.
     * @param evt A PropertyChangeEvent object describing the event source
     *            and the property that has changed.
    public void propertyChange(PropertyChangeEvent evt) {
        System.out.println("Name      = " + evt.getPropertyName());
        System.out.println("Old Value = " + evt.getOldValue());
        System.out.println("New Value = " + evt.getNewValue());

    public static void main(String[] args) {
        MyBean bean = new MyBean();
        bean.setName("My Initial Value");
        bean.setName("My New Value");
        bean.setName("My Yet Another Value");

    //~ --------------------------------------------- Bean's Getters and Setters

    public Long getId() {
        return id;

    public void setId(Long id) { = id;

    public String getName() {
        return name;

    public void setName(String name) {
        String oldValue =; = name;

        // Fires a property change event
        pcs.firePropertyChange("name", oldValue, name);


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