Java Bean - addPropertyChangeListener

[Amirr Rafique]

Hi mates

How addPropertyChangeListener() method will be called in a java bean. Please see below a simple Java bean. Please help me to understand this concept.

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
public class State {
    public static final int       NOTRUN   = 0;
    public static final int       FINISHED = 1;
    private final PropertyChangeSupport changes  = new PropertyChangeSupport( this );
    private String                name;
    private int                   state;
    public State() {     
    }
    
    public State(final String name) {
        this.name = name;
        this.state = State.NOTRUN;
    }
 
    public String getName() {
        return this.name;
    }
 
    public int getState() {
        return this.state;
    }
 
    public void setState(final int newState) {
        final int oldState = this.state;
        this.state = newState;
        this.changes.firePropertyChange( "state",
                                         oldState,
                                         newState );
    }
 
    public boolean inState(final String name,
                           final int state) {
        return this.name.equals( name ) && this.state == state;
    }
 
    public String toString() {
        switch ( this.state ) {
            case NOTRUN :
                return this.name + "[" + "NOTRUN" + "]";
            case FINISHED :
            default :
                return this.name + "[" + "FINISHED" + "]";
        }
    }
 
    public void addPropertyChangeListener(final PropertyChangeListener l) {
        this.changes.addPropertyChangeListener( l );
    }
 
    public void removePropertyChangeListener(final PropertyChangeListener l) {
        this.changes.removePropertyChangeListener( l );
    }
}