Package org.loboevolution.net

Class AbstractBean

java.lang.Object
org.loboevolution.net.AbstractBean
Direct Known Subclasses:
NameValuePair
public abstract class AbstractBean extends Object

A convenience class from which to extend all non-visual JavaBeans. It manages the PropertyChange notification system, making it relatively trivial to add support for property change events in getters/setters.

A non-visual java bean is a Java class that conforms to the JavaBean patterns to allow visual manipulation of the bean's properties and event handlers at design-time.

Here is a simple example bean that contains one property, foo, and the proper pattern for implementing property change notification: 

  public class ABean extends JavaBean {
    private String foo;

    public void setFoo(final String newFoo) {
      String old = getFoo();
      this.foo = newFoo;
      firePropertyChange("foo", old, getFoo());
   }

    public String getFoo() {
      return foo;
   }
 }

You will notice that "getFoo()" is used in the setFoo method rather than accessing "foo" directly for the gets. This is done intentionally so that if a subclass overrides getFoo() to return, for instance, a constant value the property change notification system will continue to work properly.

The firePropertyChange method takes into account the old value and the new value. Only if the two differ will it fire a property change event. So you can be assured from the above code fragment that a property change event will only occur if old is indeed different from getFoo()

JavaBean also supports VetoablePropertyChange events. These events are similar to PropertyChange events, except a special exception can be used to veto changing the property. For example, perhaps the property is changing from "fred" to "red", but a listener deems that "red" is unexceptable. In this case, the listener can fire a veto exception and the property must remain "fred". * Author rbair

  • Constructor Details

    • AbstractBean

      protected AbstractBean()
      Creates a new instance of JavaBean.

    • AbstractBean

      protected AbstractBean(PropertyChangeSupport pcs, VetoableChangeSupport vcs)
      Creates a new instance of JavaBean, using the supplied PropertyChangeSupport and VetoableChangeSupport delegates. Neither of these may be null.
      Parameters:
      pcs - the pcs
      vcs - the vcs

  • Method Details

    • addPropertyChangeListener

      public void addPropertyChangeListener(PropertyChangeListener listener)
      Add a PropertyChangeListener to the listener list. The listener is registered for all properties. The same listener object may be added more than once, and will be called as many times as it is added. If listener is null, no exception is thrown and no action is taken.
      Parameters:
      listener - The PropertyChangeListener to be added

    • removePropertyChangeListener

      public void removePropertyChangeListener(PropertyChangeListener listener)
      Remove a PropertyChangeListener from the listener list. This removes a PropertyChangeListener that was registered for all properties. If listener was added more than once to the same event source, it will be notified one less time after being removed. If listener is null, or was never added, no exception is thrown and no action is taken.
      Parameters:
      listener - The PropertyChangeListener to be removed

    • getPropertyChangeListeners

      public PropertyChangeListener[] getPropertyChangeListeners()
      Gets the property change listeners.
      Returns:
      the property change listeners

    • addPropertyChangeListener

      public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
      Add a PropertyChangeListener for a specific property. The listener will be invoked only when a call on firePropertyChange names that specific property. The same listener object may be added more than once. For each property, the listener will be invoked the number of times it was added for that property. If propertyName or listener is null, no exception is thrown and no action is taken.
      Parameters:
      propertyName - The name of the property to listen on.
      listener - The PropertyChangeListener to be added

    • removePropertyChangeListener

      public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener)
      Remove a PropertyChangeListener for a specific property. If listener was added more than once to the same event source for the specified property, it will be notified one less time after being removed. If propertyName is null, no exception is thrown and no action is taken. If listener is null, or was never added for the specified property, no exception is thrown and no action is taken.
      Parameters:
      propertyName - The name of the property that was listened on.
      listener - The PropertyChangeListener to be removed

    • getPropertyChangeListeners

      public PropertyChangeListener[] getPropertyChangeListeners(String propertyName)
      Returns an array of all the listeners which have been associated with the named property.
      Parameters:
      propertyName - The name of the property being listened to
      Returns:
      all of the PropertyChangeListeners associated with the named property. If no such listeners have been added, or if propertyName is null, an empty array is returned.

    • firePropertyChange

      protected void firePropertyChange(String propertyName, Object oldValue, Object newValue)
      Report a bound property update to any registered listeners. No event is fired if old and new are equal and non-null.

      This is merely a convenience wrapper around the more general firePropertyChange method that takes PropertyChangeEvent value.

      Parameters:
      propertyName - The programmatic name of the property that was changed.
      oldValue - The old value of the property.
      newValue - The new value of the property.

    • firePropertyChange

      protected void firePropertyChange(PropertyChangeEvent evt)
      Fire an existing PropertyChangeEvent to any registered listeners. No event is fired if the given event's old and new values are equal and non-null.
      Parameters:
      evt - The PropertyChangeEvent object.

    • fireIndexedPropertyChange

      protected void fireIndexedPropertyChange(String propertyName, int index, Object oldValue, Object newValue)
      Report a bound indexed property update to any registered listeners.

      No event is fired if old and new values are equal and non-null.

      This is merely a convenience wrapper around the more general firePropertyChange method that takes PropertyChangeEvent value.

      Parameters:
      propertyName - The programmatic name of the property that was changed.
      index - index of the property element that was changed.
      oldValue - The old value of the property.
      newValue - The new value of the property.

    • hasPropertyChangeListeners

      protected boolean hasPropertyChangeListeners(String propertyName)
      Check if there are any listeners for a specific property, including those registered on all properties. If propertyName is null, only check for listeners registered on all properties.
      Parameters:
      propertyName - the property name.
      Returns:
      true if there are one or more listeners for the given property

    • hasVetoableChangeListeners

      protected boolean hasVetoableChangeListeners(String propertyName)
      Check if there are any listeners for a specific property, including those registered on all properties. If propertyName is null, only check for listeners registered on all properties.
      Parameters:
      propertyName - the property name.
      Returns:
      true if there are one or more listeners for the given property

    • addVetoableChangeListener

      public void addVetoableChangeListener(VetoableChangeListener listener)
      Add a VetoableListener to the listener list. The listener is registered for all properties. The same listener object may be added more than once, and will be called as many times as it is added. If listener is null, no exception is thrown and no action is taken.
      Parameters:
      listener - The VetoableChangeListener to be added

    • removeVetoableChangeListener

      public void removeVetoableChangeListener(VetoableChangeListener listener)
      Remove a VetoableChangeListener from the listener list. This removes a VetoableChangeListener that was registered for all properties. If listener was added more than once to the same event source, it will be notified one less time after being removed. If listener is null, or was never added, no exception is thrown and no action is taken.
      Parameters:
      listener - The VetoableChangeListener to be removed

    • getVetoableChangeListeners

      public VetoableChangeListener[] getVetoableChangeListeners()
      Gets the vetoable change listeners.
      Returns:
      the vetoable change listeners

    • addVetoableChangeListener

      public void addVetoableChangeListener(String propertyName, VetoableChangeListener listener)
      Add a VetoableChangeListener for a specific property. The listener will be invoked only when a call on fireVetoableChange names that specific property. The same listener object may be added more than once. For each property, the listener will be invoked the number of times it was added for that property. If propertyName or listener is null, no exception is thrown and no action is taken.
      Parameters:
      propertyName - The name of the property to listen on.
      listener - The VetoableChangeListener to be added

    • removeVetoableChangeListener

      public void removeVetoableChangeListener(String propertyName, VetoableChangeListener listener)
      Remove a VetoableChangeListener for a specific property. If listener was added more than once to the same event source for the specified property, it will be notified one less time after being removed. If propertyName is null, no exception is thrown and no action is taken. If listener is null, or was never added for the specified property, no exception is thrown and no action is taken.
      Parameters:
      propertyName - The name of the property that was listened on.
      listener - The VetoableChangeListener to be removed

    • getVetoableChangeListeners

      public VetoableChangeListener[] getVetoableChangeListeners(String propertyName)
      Returns an array of all the listeners which have been associated with the named property.
      Parameters:
      propertyName - The name of the property being listened to
      Returns:
      all the VetoableChangeListeners associated with the named property. If no such listeners have been added, or if propertyName is null, an empty array is returned.

    • fireVetoableChange

      protected void fireVetoableChange(String propertyName, Object oldValue, Object newValue) throws PropertyVetoException
      Report a vetoable property update to any registered listeners. If anyone vetos the change, then fire a new event reverting everyone to the old value and then rethrow the PropertyVetoException.

      No event is fired if old and new are equal and non-null.

      Parameters:
      propertyName - The programmatic name of the property that is about to change..
      oldValue - The old value of the property.
      newValue - The new value of the property.
      Throws:
      PropertyVetoException - if the recipient wishes the property change to be rolled back.
      PropertyVetoException - if any.

    • fireVetoableChange

      protected void fireVetoableChange(PropertyChangeEvent evt) throws PropertyVetoException
      Fire a vetoable property update to any registered listeners. If anyone vetos the change, then fire a new event reverting everyone to the old value and then rethrow the PropertyVetoException.

      No event is fired if old and new are equal and non-null.

      Parameters:
      evt - The PropertyChangeEvent to be fired.
      Throws:
      PropertyVetoException - if the recipient wishes the property change to be rolled back.
      PropertyVetoException - if any.