com.jgoodies.binding

Class PresentationModel<B>

Implemented Interfaces:
Observable, Serializable

public class PresentationModel<B>
extends Model

The standard base class to implement the Presentation Model pattern, that represents the state and behavior of a presentation independently of the GUI components used in the interface. This pattern is described in Martin Fowler's upcoming addition to his "Patterns of Enterprise Application Architecture". More details around this implementation of the Presentation Model pattern and a 3-tier Swing client architecture with a presentation model layer can be found in the JGoodies Binding presentation. This architecture is supported by the JGoodies Binding library. The PresentationModel pattern is known to users of VisualWorks Smalltalk as ApplicationModel.

This class minimizes the effort required to bind, edit, buffer, and observe the bound properties of an exchangeable bean. Therefore it provides five groups of features that are described below:

  1. adapt bean properties,
  2. change the adapted bean,
  3. buffer values,
  4. observe the buffering state, and
  5. track changes in adapted bean properties.

Typically this class will be extended to add custom models, Actions, presentation logic, model operations and other higher-level behavior. However, in simple cases you can use this class as-is. Several methods are intended to be used as-is and a typical subclass should not modify them. For example #isChanged, #isBuffering, #getBean, #setBean, #getBeanChannel, #getModel, #getBufferedModel, #getTriggerChannel, #setTriggerChannel, #triggerCommit and #triggerFlush.

Adapting Bean Properties
The method getModel(String) vends ValueModels that adapt a bound bean property of an exchangeable bean. These ValueModels will be requested from an underlying BeanAdapter. To get such a model you specify the name of the bean property. All properties adapted must be read-write and must comply with the Java Bean coding conventions. In case you need to adapt a read-only or write-only property, or if the bean uses custom names for the reader and writer, use getModel(String,String,String). Also note that you must not mix calls to these methods for the same property name. For details see the JavaDoc class comment in BeanAdapter.

Changing the Adapted Bean
The adapted bean is not stored in this PresentationModel. Instead it is held by a ValueModel, the bean channel - just as in the PropertyAdapter and BeanAdapter. This indirection enables you to manage the adapted bean outside of this PresentationModel, and it enables you to share bean channels between multiple PresentationModels, PropertyAdapters, and BeanAdapters. The bean channel is used by all adapting models created by the factory methods #getModel. You can get and set the current bean by means of #getBean and #setBean. Or you can set a new value to the bean channel.

PresentationModel fires three PropertyChangeEvents if the bean changes: beforeBean, bean and afterBean. This is useful when sharing a bean channel and you must perform an operation before or after other listeners handle a bean change. Since you cannot rely on the order listeners will be notified, only the beforeBean and afterBean events are guaranteed to be fired before and after the bean change is fired. Note that #getBean() returns the new bean before any of these three PropertyChangeEvents is fired. Therefore listeners that handle these events must use the event's old and new value to determine the old and new bean. The order of events fired during a bean change is:

  1. the bean channel fires a value change,
  2. this model fires a beforeBean change,
  3. this model fires the bean change,
  4. this model fires an afterBean change.
Buffering Values
At the core of this feature are the methods getBufferedModel(String) that vend BufferedValueModels that wrap an adapted bean property. The buffer can be committed or flushed using #triggerCommit and #triggerFlush respectively.

The trigger channel is provided as a bound Java bean property triggerChannel that must be a non-null ValueModel with values of type Boolean. Attempts to read or write other value types may be rejected with runtime exceptions. By default the trigger channel is initialized as an instance of Trigger. As an alternative it can be set in the constructor.

Observing the Buffering State
This class also provides support for observing the buffering state of the BufferedValueModels created with this model. The buffering state is useful for UI actions and operations that are enabled or disabled if there are pending changes, for example on OK or APPLY button. API users can request the buffering state via #isBuffering and can observe the bound property buffering.

Tracking Changes in the Adapted Bean
PresentationModel provides support for observing bean property changes and it tracks all changes to report the overall changed state. The latter is useful to detect whether the bean has changed at all, for example to mark the bean as dirty, so it will be updated in a database. API users can request the changed state via #isChanged and can observe the bound property changed. If you want to track changes of other ValueModels, bean properties, or of submodels, register them using #observeChanged. To reset the changed state invoke #resetChanged. In case you track the changed state of submodels you should override #resetChanged to reset the changed state in these submodels.

The changed state changes once only (from false to true). If you need instant notifications about changes in the properties of the target bean, you can register PropertyChangeListeners with this model. This is useful if you change the bean and don't want to move your listeners from one bean to the other. And it's useful if you want to observe multiple bean properties at the same time. These listeners are managed by the method set #addBeanPropertyChangeListener and #removeBeanPropertyChangeListener. Listeners registered via these methods will be removed from the old bean before the bean changes and will be re-added after the new bean has been set. Therefore these listeners will be notified about changes only if the current bean changes a property. They won't be notified if the bean changes - and in turn the property value. If you want to observes property changes caused by bean changes too, register with the adapting ValueModel as returned by #getModel(String).

Instance Creation
PresentationModel can be instantiated using four different constructors: you can specify the target bean directly, or you can provide a bean channel to access the bean indirectly. In the latter case you specify a ValueModel that holds the bean that in turn holds the adapted property. In both cases the target bean is accessed indirectly through the bean channel. In both cases you can specify a custom trigger channel, or you can use a default trigger channel.

Note: This PresentationModel provides bound bean properties and you can register and unregister PropertyChangeListers as usual using #addPropertyChangeListener and #removePropertyChangeListener. Do not mix up the model listeners with the listeners registered with the bean.

Warning: PresentationModels register a PropertyChangeListener with the target bean. Hence, a bean has a reference to all PresentationModels that hold it as target bean. To avoid memory leaks it is recommended to remove this listener if the bean lives much longer than the PresentationModel, enabling the garbage collector to remove the PresentationModel. Setting a PresentationModel's target bean to null removes this listener, which in turn clears the reference from the bean to the PresentationModel. To do so, you can call setBean(null) or set the bean channel's value to null. As an alternative you can use event listener lists in your beans that implement references with WeakReference. Setting the bean to null has side effects, which is fine in most cases. However, you can release all listeners by calling #release.

TODO: Further improve the class comment.

TODO: Consider adding a feature to ensure that update notifications are performed in the event dispatch thread. In case the adapted bean is changed in a thread other than the event dispatch thread, such a feature would help complying with Swing's single thread rule. The feature could be implemented by an extended PropertyChangeSupport.

TODO: I plan to improve the support for adapting beans that do not fire PropertyChangeEvents. This affects the classes PropertyAdapter, BeanAdapter, and PresentationModel. Basically the PropertyAdapter and the BeanAdapter's internal SimplePropertyAdapter's shall be able to optionally self-fire a PropertyChangeEvent in case the bean does not. There are several downsides with self-firing events compared to bound bean properties. See Issue 49 for more information about the downsides.

The observeChanges constructor parameter shall be replaced by a more fine-grained choice to not observe (former observeChanges=false), to observe bound properties (former observeChanges=true), and a new setting for self-firing PropertyChangeEvents if a value is set. The latter case may be further split up to specify how the self-fired PropertyChangeEvent is created:

  1. oldValue=null, newValue=null
  2. oldValue=null, newValue=the value set
  3. oldValue=value read before the set, newValue=the value set
  4. oldValue=value read before the set, newValue=value read after the set
Version:
$Revision: 1.20 $
Author:
Karsten Lentzsch
See Also:
BeanAdapter, ValueModel, PropertyAdapter, Trigger

Field Summary

static String
PROPERTYNAME_AFTER_BEAN
The property name used in the PropertyChangeEvent that is fired after the bean property fires its PropertyChangeEvent.
static String
PROPERTYNAME_BEAN
The name of the read-write bound property that holds the target bean.
static String
PROPERTYNAME_BEFORE_BEAN
The property name used in the PropertyChangeEvent that is fired before the bean property fires its PropertyChangeEvent.
static String
PROPERTYNAME_BUFFERING
The name of the read-only bound bean property that indicates whether one of the buffered models is buffering.
static String
PROPERTYNAME_CHANGED
The name of the read-only bound bean property that indicates whether one of the observed models has changed.
static String
PROPERTYNAME_TRIGGERCHANNEL
The name of the read-write bound bean property for the trigger channel that is shared by all PropertyAdapters that are created via #getBufferedModel.

Constructor Summary

PresentationModel(B bean)
Constructs a PresentationModel that adapts properties of the given bean.
PresentationModel(B bean, ValueModel triggerChannel)
Constructs a PresentationModel on the given bean using the given trigger channel.
PresentationModel(ValueModel beanChannel)
Constructs a PresentationModel on the given bean channel.
PresentationModel(ValueModel beanChannel, ValueModel triggerChannel)
Constructs a PresentationModel on the given bean channel using the given trigger channel.

Method Summary

void
addBeanPropertyChangeListener(PropertyChangeListener listener)
Adds a PropertyChangeListener to the list of bean listeners.
void
addBeanPropertyChangeListener(String propertyName, PropertyChangeListener listener)
Adds a PropertyChangeListener to the list of bean listeners for a specific property.
void
afterBeanChange(B oldBean, B newBean)
The underlying BeanAdapter has changed the target bean.
void
beforeBeanChange(B oldBean, B newBean)
The underlying BeanAdapter is about to change the bean.
protected BeanAdapter
createBeanAdapter(ValueModel beanChannel)
Creates and returns a BeanAdapter for the given bean channel.
B
getBean()
Returns the bean that holds the adapted properties.
ValueModel
getBeanChannel()
Returns the ValueModel that holds the bean that in turn holds the adapted properties.
PropertyChangeListener[]
getBeanPropertyChangeListeners()
Returns an array of all the property change listeners registered on this component.
PropertyChangeListener[]
getBeanPropertyChangeListeners(String propertyName)
Returns an array of all the listeners which have been associated with the named property.
ComponentValueModel
getBufferedComponentModel(String propertyName)
Looks up or creates a buffered component adapter to the read-write property with the given name on this PresentationModel's bean channel.
BufferedValueModel
getBufferedModel(String propertyName)
Looks up or creates a buffered adapter to the read-write property with the given name on this PresentationModel's bean channel.
BufferedValueModel
getBufferedModel(String propertyName, String getterName, String setterName)
Looks up or creates a buffered adapter to the read-write property with the given name on this PresentationModel's bean channel using the specified getter and setter name to read and write values.
Object
getBufferedValue(String propertyName)
Returns the value of specified buffered bean property.
ComponentValueModel
getComponentModel(String propertyName)
Looks up and lazily creates a ComponentValueModel that adapts the bound property with the specified name.
AbstractValueModel
getModel(String propertyName)
Looks up and lazily creates a ValueModel that adapts the bound property with the specified name.
AbstractValueModel
getModel(String propertyName, String getterName, String setterName)
Looks up and lazily creates a ValueModel that adapts the bound property with the given name.
ValueModel
getTriggerChannel()
Returns a ValueModel that can be shared and used to trigger commit and flush events in BufferedValueModels.
Object
getValue(String propertyName)
Returns the value of specified bean property, null if the current bean is null.
boolean
isBuffering()
Answers whether any of the buffered models is buffering.
boolean
isChanged()
Answers whether one of the registered ValueModels has changed since the changed state has been reset last time.
void
observeChanged(Object bean, String propertyName)
Observes the specified readable bound bean property in the given bean.
void
observeChanged(ValueModel valueModel)
Observes value changes in the given ValueModel.
void
release()
Removes the PropertyChangeHandler from the observed bean, if the bean is not null.
void
removeBeanPropertyChangeListener(PropertyChangeListener listener)
Removes a PropertyChangeListener from the list of bean listeners.
void
removeBeanPropertyChangeListener(String propertyName, PropertyChangeListener listener)
Removes a PropertyChangeListener from the listener list for a specific property.
void
resetChanged()
Resets this model's changed state to false.
void
retractInterestFor(Object bean, String propertyName)
Retracts interest for the specified readable bound bean property in the given bean.
void
retractInterestFor(ValueModel valueModel)
Retracts interest for value changes in the given ValueModel.
void
setBean(B newBean)
Sets a new bean as content of the bean channel.
void
setBufferedValue(String propertyName, Object newValue)
Buffers the given value for the specified bean property.
protected void
setChanged(boolean newValue)
void
setTriggerChannel(ValueModel newTriggerChannel)
Sets the given ValueModel as this model's new trigger channel.
void
setValue(String propertyName, Object newValue)
Sets the given new value for the specified bean property.
void
setVetoableValue(String propertyName, Object newValue)
Sets a new value for the specified bean property.
void
triggerCommit()
Sets the trigger channel to true which in turn triggers commit events in all BufferedValueModels that share this trigger.
void
triggerFlush()
Sets the trigger channel to false which in turn triggers flush events in all BufferedValueModels that share this trigger.

Methods inherited from class com.jgoodies.binding.beans.Model

addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, equals, fireIndexedPropertyChange, fireIndexedPropertyChange, fireIndexedPropertyChange, fireMultiplePropertiesChanged, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener

Field Details

PROPERTYNAME_AFTER_BEAN

public static final String PROPERTYNAME_AFTER_BEAN
The property name used in the PropertyChangeEvent that is fired after the bean property fires its PropertyChangeEvent. Useful to perform an operation after listeners that handle the bean change are notified. See also the class comment.

PROPERTYNAME_BEAN

public static final String PROPERTYNAME_BEAN
The name of the read-write bound property that holds the target bean.
See Also:
getBean(), setBean(Object)

PROPERTYNAME_BEFORE_BEAN

public static final String PROPERTYNAME_BEFORE_BEAN
The property name used in the PropertyChangeEvent that is fired before the bean property fires its PropertyChangeEvent. Useful to perform an operation before listeners that handle the bean change are notified. See also the class comment.

PROPERTYNAME_BUFFERING

public static final String PROPERTYNAME_BUFFERING
The name of the read-only bound bean property that indicates whether one of the buffered models is buffering.

PROPERTYNAME_CHANGED

public static final String PROPERTYNAME_CHANGED
The name of the read-only bound bean property that indicates whether one of the observed models has changed.

PROPERTYNAME_TRIGGERCHANNEL

public static final String PROPERTYNAME_TRIGGERCHANNEL
The name of the read-write bound bean property for the trigger channel that is shared by all PropertyAdapters that are created via #getBufferedModel.

Constructor Details

PresentationModel

public PresentationModel(B bean)
Constructs a PresentationModel that adapts properties of the given bean.

Installs a default bean channel that checks the identity not equity to ensure that listeners are unregistered properly if the old and new bean are equal but not the same.

Installs a Trigger as initial trigger channel.

Parameters:
bean - the bean that holds the properties to adapt

PresentationModel

public PresentationModel(B bean,
                         ValueModel triggerChannel)
Constructs a PresentationModel on the given bean using the given trigger channel. The bean provides the properties to adapt.

Installs a default bean channel that checks the identity not equity to ensure that listeners are unregistered properly if the old and new bean are equal but not the same.

The trigger channel is shared by all buffered models that are created using #getBufferedModel. It can be replaced by any other Boolean ValueModel later. Note that PresentationModel observes trigger value changes, not value state. Therefore you must ensure that customer triggers report value changes when asked to commit or flush. See the Trigger implementation for an example.

Parameters:
bean - the bean that holds the properties to adapt
triggerChannel - the ValueModel that triggers commit and flush events

PresentationModel

public PresentationModel(ValueModel beanChannel)
Constructs a PresentationModel on the given bean channel. This channel holds a bean that in turn holds the properties to adapt.

It is strongly recommended that the bean channel checks the identity not equity. This ensures that listeners are unregistered properly if the old and new bean are equal but not the same.

The trigger channel is initialized as a Trigger. It may be replaced by any other Boolean ValueModel later. Note that PresentationModel observes trigger value changes, not value state. Therefore you must ensure that customer triggers report value changes when asked to commit or flush. See the Trigger implementation for an example.

Parameters:
beanChannel - the ValueModel that holds the bean

PresentationModel

public PresentationModel(ValueModel beanChannel,
                         ValueModel triggerChannel)
Constructs a PresentationModel on the given bean channel using the given trigger channel. The bean channel holds a bean that in turn holds the properties to adapt.

It is strongly recommended that the bean channel checks the identity not equity. This ensures that listeners are unregistered properly if the old and new bean are equal but not the same.

The trigger channel is shared by all buffered models that are created using #buffer. It can be replaced by any other Boolean ValueModel later. Note that PresentationModel observes trigger value changes, not value state. Therefore you must ensure that customer triggers report value changes when asked to commit or flush. See the Trigger implementation for an example.

Parameters:
beanChannel - the ValueModel that holds the bean
triggerChannel - the ValueModel that triggers commit and flush events

Method Details

addBeanPropertyChangeListener

public void addBeanPropertyChangeListener(PropertyChangeListener listener)
Adds a PropertyChangeListener to the list of bean listeners. The listener is registered for all bound properties of the target bean.

The listener will be notified if and only if this BeanAdapter's current bean changes a property. It'll not be notified if the bean changes.

If listener is null, no exception is thrown and no action is performed.

Parameters:
listener - the PropertyChangeListener to be added

addBeanPropertyChangeListener

public void addBeanPropertyChangeListener(String propertyName,
                                          PropertyChangeListener listener)
Adds a PropertyChangeListener to the list of bean listeners for a specific property. The specified property may be user-defined.

The listener will be notified if and only if this BeanAdapter's current bean changes the specified property. It'll not be notified if the bean changes. If you want to observe property changes and bean changes, you may observe the ValueModel that adapts this property - as returned by #getModel(String).

Note that if the bean is inheriting a bound property, then no event will be fired in response to a change in the inherited property.

If listener is null, no exception is thrown and no action is performed.

Parameters:
propertyName - one of the property names listed above
listener - the PropertyChangeListener to be added

afterBeanChange

public void afterBeanChange(B oldBean,
                            B newBean)
The underlying BeanAdapter has changed the target bean. Allows to perform actions after the bean changed. For example you can re-add listeners that were removed in #beforeBeanChange. Or you can reset values, reset custom changed state, set fields to null etc.

The default behavior resets the change tracker's changed state and fires a PropertyChangeEvent for the property #PROPERTYNAME_AFTER_BEAN. Note: Subclasses that override this method must invoke super or perform the same behavior.

This method is invoked by the BeanChangeHandler listening to the afterBean non-readable property of the BeanAdapter.

Parameters:
oldBean - the bean that was adapted before the change
newBean - the bean that is already the new target bean

beforeBeanChange

public void beforeBeanChange(B oldBean,
                             B newBean)
The underlying BeanAdapter is about to change the bean. Allows to perform actions before the bean change happens. For example you can remove listeners that shall not be notified if adapted properties change just because of the bean change. Or you can reset values, set fields to null etc.

The default behavior fires a PropertyChangeEvent for property #PROPERTYNAME_BEFORE_BEAN. Note: Subclasses that override this method must invoke super or perform the same behavior.

This method is invoked by the BeanChangeHandler listening to the beforeBean non-readable property of the BeanAdapter.

Parameters:
oldBean - the bean before the change
newBean - the bean that will be adapted after the change

createBeanAdapter

protected BeanAdapter createBeanAdapter(ValueModel beanChannel)
Creates and returns a BeanAdapter for the given bean channel. For compatibility with the 1.0.x, 1.1.x, and 1.2.x series, this default implementation creates a BeanAdapter that always observes the bean. Subclasses may override to observe only observable beans.

Here's an example code for a custom implementation:

  boolean observe =
        (beanChannel == null)
     || (beanChannel.getValue() == null)
     || BeanUtils.supportsBoundProperties((beanChannel.getValue().getClass());
  return new BeanAdapter(beanChannel, observe);
  

A future implementation shall return a BeanAdapter-like interface, not a BeanAdapter.

Parameters:
beanChannel - the ValueModel that holds the bean
Returns:
the created bean adapter
Since:
1.3


getBeanChannel

public ValueModel getBeanChannel()
Returns the ValueModel that holds the bean that in turn holds the adapted properties. This bean channel is shared by the PropertyAdapters created by the factory methods #getModel and #getBufferedModel.
Returns:
the ValueModel that holds the bean that in turn holds the adapted properties
See Also:
getBean(), setBean(Object)



getBufferedComponentModel

public ComponentValueModel getBufferedComponentModel(String propertyName)
Looks up or creates a buffered component adapter to the read-write property with the given name on this PresentationModel's bean channel. Creates a ComponentValueModel that wraps a BufferedValueModel that in turn wraps a ValueModel that adapts the bean property with the specified name. The buffered model uses this PresentationModel's trigger channel to listen for commit and flush events. The ComponentValueModel allows to set component state in this presentation model.

The created ComponentValueModel is stored in a Map. Hence subsequent calls to this method with the same property name return the same ComponentValueModel.

To prevent potential runtime errors this method eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getBufferedModel(String, String, String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method you must not call #getBufferedModel(String, String, String) with a non-null getter or setter name. And vice versa, once you've called the latter method with a non-null getter or setter name, you must not call this method.

Parameters:
propertyName - the name of the read-write property to adapt
Returns:
a ComponentValueModel that wraps a buffered adapter to the property with the given name on this model's bean channel using this model's trigger channel
Since:
1.1

getBufferedModel

public BufferedValueModel getBufferedModel(String propertyName)
Looks up or creates a buffered adapter to the read-write property with the given name on this PresentationModel's bean channel. Creates a BufferedValueModel that wraps a ValueModel that adapts the bean property with the specified name. The buffered model uses this PresentationModel's trigger channel to listen for commit and flush events.

The created BufferedValueModel is stored in a Map. Hence subsequent calls to this method with the same property name return the same BufferedValueModel.

To prevent potential runtime errors this method eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getBufferedModel(String, String, String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method you must not call #getBufferedModel(String, String, String) with a non-null getter or setter name. And vice versa, once you've called the latter method with a non-null getter or setter name, you must not call this method.

Parameters:
propertyName - the name of the read-write property to adapt
Returns:
a buffered adapter to the property with the given name on this model's bean channel using this model's trigger channel

getBufferedModel

public BufferedValueModel getBufferedModel(String propertyName,
                                           String getterName,
                                           String setterName)
Looks up or creates a buffered adapter to the read-write property with the given name on this PresentationModel's bean channel using the specified getter and setter name to read and write values. Creates a BufferedValueModel that wraps a ValueModel that adapts the bean property with the specified name. The buffered model uses this PresentationModel's trigger channel to listen for commit and flush events.

The created BufferedValueModel is stored in a Map so it can be looked up if it is requested multiple times.

To prevent potential runtime errors this method eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getBufferedModel(String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method with a non-null getter or setter name, you must not call #getBufferedModel(String). And vice versa, once you've called the latter method you must not call this method with a non-null getter or setter name.

Parameters:
propertyName - the name of the property to adapt
getterName - the name of the method that reads the value
setterName - the name of the method that sets the value
Returns:
a buffered adapter to the property with the given name on this model's bean channel using this model's trigger channel

getBufferedValue

public Object getBufferedValue(String propertyName)
Returns the value of specified buffered bean property. It is a shorthand for writing
getBufferedModel(propertyName).getValue()
As a side-effect, this method may create a buffered model.
Parameters:
propertyName - the name of the property to be read
Returns:
the value of the adapted bean property, null if the bean is null
Since:
1.1

getComponentModel

public ComponentValueModel getComponentModel(String propertyName)
Looks up and lazily creates a ComponentValueModel that adapts the bound property with the specified name. Uses the standard Bean introspection to look up the getter and setter names.

Subsequent calls to this method with the same property name return the same ComponentValueModel.

To prevent potential runtime errors it eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getModel(String, String, String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method you must not call #getModel(String, String, String) with a non-null getter or setter name. And vice versa, once you've called the latter method with a non-null getter or setter name, you must not call this method.

This returned ComponentValueModel provides convenience type converter method from AbstractValueModel and allows to modify GUI state such as enabled, visible, and editable in this presentation model. This can significantly shrink the source code necessary to handle GUI state changes.

Parameters:
propertyName - the name of the property to adapt
Returns:
a ValueModel that adapts the property with the specified name
Since:
1.1

getModel

public AbstractValueModel getModel(String propertyName)
Looks up and lazily creates a ValueModel that adapts the bound property with the specified name. Uses the Bean introspection to look up the getter and setter names.

Subsequent calls to this method with the same property name return the same ValueModel.

To prevent potential runtime errors it eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getModel(String, String, String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method you must not call #getModel(String, String, String) with a non-null getter or setter name. And vice versa, once you've called the latter method with a non-null getter or setter name, you must not call this method.

This method uses a return type of AbstractValueModel, not a ValueModel. This makes the AbstractValueModel convenience type converters available, which can significantly shrink the source code necessary to read and write values from/to these models.

Parameters:
propertyName - the name of the property to adapt
Returns:
a ValueModel that adapts the property with the specified name

getModel

public AbstractValueModel getModel(String propertyName,
                                   String getterName,
                                   String setterName)
Looks up and lazily creates a ValueModel that adapts the bound property with the given name. Unlike #getModel(String) this method bypasses the Bean Introspection and uses the given getter and setter names to setup the access to the adapted Bean property.

Subsequent calls to this method with the same parameters will return the same ValueModel.

To prevent potential runtime errors this method eagerly looks up the associated PropertyDescriptor if the target bean is not null.

For each property name all calls to this method and to #getModel(String) must use the same getter and setter names. Attempts to violate this constraint will be rejected with an IllegalArgumentException. Especially once you've called this method with a non-null getter or setter name, you must not call #getModel(String). And vice versa, once you've called the latter method you must not call this method with a non-null getter or setter name.

This method uses a return type of AbstractValueModel, not a ValueModel. This makes the AbstractValueModel convenience type converters available, which can significantly shrink the source code necessary to read and write values from/to these models.

Parameters:
propertyName - the name of the property to adapt
getterName - the name of the method that reads the value
setterName - the name of the method that sets the value
Returns:
a ValueModel that adapts the property with the specified name

getTriggerChannel

public ValueModel getTriggerChannel()
Returns a ValueModel that can be shared and used to trigger commit and flush events in BufferedValueModels. The trigger channel's value changes to true in #triggerCommit and it changes to false in #triggerFlush.

This trigger channel is used to commit and flush values in the BufferedValueModels returned by #getBufferedModel.

Returns:
this model's trigger channel

getValue

public Object getValue(String propertyName)
Returns the value of specified bean property, null if the current bean is null.

This operation is supported only for readable bean properties.

Parameters:
propertyName - the name of the property to be read
Returns:
the value of the adapted bean property, null if the bean is null
Since:
1.1

isBuffering

public boolean isBuffering()
Answers whether any of the buffered models is buffering. Useful to enable and disable UI actions and operations that depend on the buffering state.
Returns:
true if any of the buffered models is buffering, false, if all buffered models write-through



observeChanged

public void observeChanged(ValueModel valueModel)
Observes value changes in the given ValueModel.
Parameters:
valueModel - the ValueModel to observe

release

public void release()
Removes the PropertyChangeHandler from the observed bean, if the bean is not null. Also removes all listeners from the bean that have been registered with #addBeanPropertyChangeListener before.

PresentationModels have a PropertyChangeListener registered with the target bean. Hence, a bean has a reference to all PresentationModels that hold it as bean. To avoid memory leaks it is recommended to remove this listener, if the bean lives much longer than the PresentationModel, enabling the garbage collector to remove the PresentationModel. To do so, you can call setBean(null) or set the bean channel's value to null. As an alternative you can use event listener lists in your beans that implement references with WeakReference.

Setting the bean to null has side-effects, for example the model fires a change event for the bound property bean and other properties. And the value of ValueModel's vent by this model may change. However, typically this is fine and setting the bean to null is the first choice for removing the reference from the bean to the PresentationModel. Another way to clear the reference from the target bean is to call this #release method. It has no side-effects, but the PresentationModel must not be used anymore once #release has been called.

Since:
1.2
See Also:
setBean(Object), java.lang.ref.WeakReference





retractInterestFor

public void retractInterestFor(ValueModel valueModel)
Retracts interest for value changes in the given ValueModel.
Parameters:
valueModel - the ValueModel to observe


setBufferedValue

public void setBufferedValue(String propertyName,
                             Object newValue)
Buffers the given value for the specified bean property. It is a shorthand for writing
getBufferedModel(propertyName).setValue(newValue)
As a side-effect, this method may create a buffered model.
Parameters:
propertyName - the name of the property to set
newValue - the value to set
Since:
1.1

setChanged

protected void setChanged(boolean newValue)

setTriggerChannel

public void setTriggerChannel(ValueModel newTriggerChannel)
Sets the given ValueModel as this model's new trigger channel. Sets the new trigger channel in all existing BufferedValueModels that have been created using #getBufferedModel. Subsequent invocations of #triggerCommit and #triggerFlush will trigger commit and flush events using the new trigger channel.
Parameters:
newTriggerChannel - the ValueModel to be set as this model's new trigger channel

setValue

public void setValue(String propertyName,
                     Object newValue)
Sets the given new value for the specified bean property. Does nothing if this adapter's bean is null. If the setter associated with the propertyName throws a PropertyVetoException, it is silently ignored.

Notifies the associated value change listeners if the bean reports a property change. Note that a bean may suppress PropertyChangeEvents if the old and new value are the same, or if the old and new value are equal.

This operation is supported only for writable bean properties.

Parameters:
propertyName - the name of the property to set
newValue - the value to set
Since:
1.1

setVetoableValue

public void setVetoableValue(String propertyName,
                             Object newValue)
            throws PropertyVetoException
Sets a new value for the specified bean property. Does nothing if the bean is null. If the setter associated with the propertyName throws a PropertyVetoException, this methods throws the same exception.

Notifies the associated value change listeners if the bean reports a property change. Note that a bean may suppress PropertyChangeEvents if the old and new value are the same, or if the old and new value are equal.

This operation is supported only for writable bean properties.

Parameters:
propertyName - the name of the property to set
newValue - the value to set
Since:
1.1



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