org.jdesktop.beansbinding
Class BeanProperty<S,V>

java.lang.Object
  org.jdesktop.beansbinding.Property<S,V>
      org.jdesktop.beansbinding.PropertyHelper<S,V>
          org.jdesktop.beansbinding.BeanProperty<S,V>

Type Parameters:

S - the type of source object that this BeanProperty operates on

V - the type of value that this BeanProperty represents

public final class BeanProperty<S,V>
extends PropertyHelper<S,V>

An implementation of Property that uses a simple dot-separated path syntax to address Java Beans properties of source objects. For example, to create a property representing the firstName property of an obect:

    BeanProperty.create("firstName");

Or to create a property representing the firstName property of an object's mother property:

    BeanProperty.create("mother.firstName");
 

An instance of BeanProperty is immutable and can be used with different source objects. When a PropertyStateListener is added to a BeanProperty for a given source object, the BeanProperty starts listening to all objects along the path (based on that source object) for change notification, and reflects any changes by notifying the listener associated with the property for that source object. So, in the second example above, if a PropertyStateListener is added to the property for an object Duke, the PropertyStateListener is notified when either Duke's mother changes (if the new mother's name is different), or Duke's mother's firstName changes.

It is very important that any bean properties addressed via a BeanProperty follow the Java Beans specification, including firing property change notification; otherwise, BeanProperty cannot respond to change. As some beans outside of your control may not follow the Java Beans specification, BeanProperty always checks the BeanAdapterFactory to see if a delegate provider has been registered to provide a delegate bean to take the place of an object for a given property. See the ext package level documentation for more details.

When there are no PropertyStateListeners installed on a BeanProperty for a given source, all Property methods act by traversing the entire path from the source to the end point, thereby always providing "live" information. On the contrary, when there are PropertyStateListeners installed, the beans along the path (including the final value) are cached, and only updated upon notification of change from a bean. Again, this makes it very important that any bean property that could change along the path fires property change notification.

Readability of a BeanProperty for a given source is defined as follows: A BeanProperty is readable for a given source if and only if a) each bean in the path, starting with the source, defines a Java Beans getter method for the the property to be read on it AND b) each bean in the path, starting with the source and ending with the bean on which we read the final property, is non-null. The final value being null does not affect the readability.

So, in the second example given earlier, the BeanProperty is readable for (@code Duke} when all of the following are true: Duke defines a Java Beans getter for mother, Duke's mother defines a Java Beans getter for firstName, Duke is non-null, Duke's mother is non-null. The BeanProperty is therefore unreadable when any of the following is true: Duke does not define a Java Beans getter for mother, Duke's mother does not define a Java Beans getter for firstName, Duke is null, Duke's mother is null.

Writeability of a BeanProperty for a given source is defined as follows: A BeanProperty is writeable for a given source if and only if a) each bean in the path, starting with the source and ending with the bean on which we set the final property, defines a Java Beans getter method for the property to be read on it AND b) the bean on which we set the final property defines a Java Beans setter for the property to be set on it AND c) each bean in the path, starting with the source and ending with the bean on which we set the final property, is non-null. The final value being null does not affect the writeability.

So, in the second example given earlier, the BeanProperty is writeable for Duke when all of the following are true: Duke defines a Java Beans getter for mother, Duke's mother defines a Java Beans setter for firstName, Duke is non-null, Duke's mother is non-null. The BeanProperty is therefore unreadable when any of the following is true: Duke does not define a Java Beans getter for mother, Duke's mother does not define a Java Beans setter for firstName, Duke is null, Duke's mother is null.

In addition to working on Java Beans properties, any object in the path can be an instance of Map. In this case, the Map's get method is used with the property name as the getter, and the Map's put method is used with the property name as the setter. BeanProperty can only respond to changes in Maps if they are instances of ObservableMap.

Some methods in this class document that they can throw PropertyResolutionException if an exception occurs while trying to resolve the path. The throwing of this exception represents an abnormal condition and if listeners are installed for the given source object, leaves the BeanProperty in an inconsistent state for that source object. A BeanProperty should not be used again for that same source object after such an exception without first removing all listeners associated with the BeanProperty for that source object.

Method Summary

static <S,V> BeanProperty<S,V>	create(Property<S,?> baseProperty, java.lang.String path) Creates an instance of BeanProperty for the given base property and path.
static <S,V> BeanProperty<S,V>	create(java.lang.String path) Creates an instance of BeanProperty for the given path.
V	getValue(S source) Returns the value of this Property for the given source.
java.lang.Class<? extends V>	getWriteType(S source) Returns the type of object that is suitable for setting as the value of this Property by calls to setValue.
boolean	isReadable(S source) Returns whether or not the Property is readable for the given source.
boolean	isWriteable(S source) Returns whether or not the Property is writeable for the given source.
protected void	listeningStarted(S source) Called when this PropertyHelper changes from having no listeners installed for the given source object to having listeners installed for the given source object.
protected void	listeningStopped(S source) Called when this PropertyHelper changes from having listeners installed for the given source object to having no listeners installed for the given source object.
void	setValue(S source, V value) Sets the value of this Property for the given source.
java.lang.String	toString() Returns a string representation of the BeanProperty.

Methods inherited from class org.jdesktop.beansbinding.PropertyHelper

addPropertyStateListener, firePropertyStateChange, getPropertyStateListeners, isListening, removePropertyStateListener

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

create

public static final <S,V> BeanProperty<S,V> create(java.lang.String path)

Creates an instance of BeanProperty for the given path.

Parameters:

path - the path

Returns:

an instance of BeanProperty for the given path

Throws:

java.lang.IllegalArgumentException - if the path is null, or contains no property names

create

public static final <S,V> BeanProperty<S,V> create(Property<S,?> baseProperty,
                                                   java.lang.String path)

Creates an instance of BeanProperty for the given base property and path. The path is relative to the value of the base property.

Parameters:

baseProperty - the base property

path - the path

Returns:

an instance of BeanProperty for the given base property and path

Throws:

java.lang.IllegalArgumentException - if the path is null, or contains no property names

getWriteType

public java.lang.Class<? extends V> getWriteType(S source)

Returns the type of object that is suitable for setting as the value of this Property by calls to setValue.

See the class level documentation for the definition of writeability.

Specified by:

getWriteType in class PropertyHelper<S,V>

Parameters:

source - the source object on which to operate

Returns:

the type of object suitable for setting as the value

Throws:

java.lang.UnsupportedOperationException - if the Property is not writeable for the given source

PropertyResolutionException - if an exception occurs while resolving the path

See Also:

setValue(S, V), isWriteable(S)

getValue

public V getValue(S source)

Returns the value of this Property for the given source.

See the class level documentation for the definition of readability.

Specified by:

getValue in class PropertyHelper<S,V>

Parameters:

source - the source object on which to operate

Returns:

the value of this Property for the given source

Throws:

java.lang.UnsupportedOperationException - if the Property is not readable for the given source

PropertyResolutionException - if an exception occurs while resolving the path

See Also:

isReadable(S)

setValue

public void setValue(S source,
                     V value)

Sets the value of this Property for the given source.

See the class level documentation for the definition of writeability.

Specified by:

setValue in class PropertyHelper<S,V>

Parameters:

source - the source object on which to operate

value - the new value for the Property

Throws:

java.lang.UnsupportedOperationException - if the Property is not writeable for the given source

PropertyResolutionException - if an exception occurs while resolving the path

See Also:

isWriteable(S), getWriteType(S)

isReadable

public boolean isReadable(S source)

Returns whether or not the Property is readable for the given source.

See the class level documentation for the definition of readability.

Specified by:

isReadable in class PropertyHelper<S,V>

Parameters:

source - the source object on which to operate

Returns:

whether or not the Property is readable for the given source.

Throws:

java.lang.UnsupportedOperationException

PropertyResolutionException - if an exception occurs while resolving the path

See Also:

isWriteable(S)

isWriteable

public boolean isWriteable(S source)

Returns whether or not the Property is writeable for the given source.

See the class level documentation for the definition of writeability.

Specified by:

isWriteable in class PropertyHelper<S,V>

Parameters:

source - the source object on which to operate

Returns:

whether or not the Property is writeable for the given source.

Throws:

java.lang.UnsupportedOperationException

PropertyResolutionException - if an exception occurs while resolving the path

See Also:

isReadable(S)

listeningStarted

protected final void listeningStarted(S source)

Description copied from class: PropertyHelper

Called when this PropertyHelper changes from having no listeners installed for the given source object to having listeners installed for the given source object. This is the ideal time for subclasses to install any listeners needed to track change on the source object.

Overrides:

listeningStarted in class PropertyHelper<S,V>

See Also:

PropertyHelper.listeningStopped(S)

listeningStopped

protected final void listeningStopped(S source)

Description copied from class: PropertyHelper

Called when this PropertyHelper changes from having listeners installed for the given source object to having no listeners installed for the given source object. This is the ideal time for subclasses to remove any listeners that they've installed to track changes on the source object.

Overrides:

listeningStopped in class PropertyHelper<S,V>

See Also:

PropertyHelper.listeningStopped(S)

toString

public java.lang.String toString()

Returns a string representation of the BeanProperty. This method is intended to be used for debugging purposes only, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this BeanProperty