javafx.beans.binding

Class ObjectBinding<T>

java.lang.Object

javafx.beans.binding.ObjectExpression<T>

javafx.beans.binding.ObjectBinding<T>

Type Parameters:

T - the type of the wrapped Object

All Implemented Interfaces:

Binding<T>

Direct Known Subclasses:

When.ObjectCondition

public abstract class ObjectBinding<T>
extends ObjectExpression<T>
implements Binding<T>

Base class that provides most of the functionality needed to implement a Binding of an Object.

ObjectBinding provides a simple invalidation-scheme. An extending class can register dependencies by calling bind(Observable...). If One of the registered dependencies becomes invalid, this ObjectBinding is marked as invalid. With unbind(Observable...) listening to dependencies can be stopped.

To provide a concrete implementation of this class, the method computeValue() has to be implemented to calculate the value of this binding based on the current state of the dependencies. It is called when get() is called for an invalid binding.

See DoubleBinding for an example how this base class can be extended.

Since:

JavaFX 2.0

See Also:

Binding, ObjectExpression

Field Summary

Fields

Modifier and Type	Field and Description
private <any>	helper
private BindingHelperObserver	observer
private boolean	valid
private T	value

Constructor Summary

Constructors

Constructor and Description
ObjectBinding()

Method Summary

Modifier and Type	Method and Description
void	addListener(<any> listener)
void	addListener(InvalidationListener listener)
protected void	bind(Observable... dependencies) Start observing the dependencies for changes.
protected abstract T	computeValue() Calculates the current value of this binding.
void	dispose() A default implementation of dispose() that is empty.
T	get() Returns the result of computeValue().
<any>	getDependencies() A default implementation of getDependencies() that returns an empty javafx.collections.ObservableList.
void	invalidate() Mark a binding as invalid.
boolean	isValid() Checks if a binding is valid.
protected void	onInvalidating() The method onInvalidating() can be overridden by extending classes to react, if this binding becomes invalid.
void	removeListener(<any> listener)
void	removeListener(InvalidationListener listener)
java.lang.String	toString() Returns a string representation of this ObjectBinding object.
protected void	unbind(Observable... dependencies) Stop observing the dependencies for changes.

Methods inherited from class javafx.beans.binding.ObjectExpression

asString, asString, asString, getValue, isEqualTo, isNotEqualTo, isNotNull, isNull, objectExpression

Methods inherited from class java.lang.Object

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

Field Detail

value

private T value

valid

private boolean valid

observer

private BindingHelperObserver observer

helper

private <any> helper

Constructor Detail

ObjectBinding

public ObjectBinding()

Method Detail

addListener

public void addListener(InvalidationListener listener)

removeListener

public void removeListener(InvalidationListener listener)

addListener

public void addListener(<any> listener)

removeListener

public void removeListener(<any> listener)

bind

protected final void bind(Observable... dependencies)

Start observing the dependencies for changes. If the value of one of the dependencies changes, the binding is marked as invalid.

Parameters:

dependencies - the dependencies to observe

unbind

protected final void unbind(Observable... dependencies)

Stop observing the dependencies for changes.

Parameters:

dependencies - the dependencies to stop observing

dispose

public void dispose()

A default implementation of dispose() that is empty.

Specified by:

dispose in interface Binding<T>

getDependencies

public <any> getDependencies()

A default implementation of getDependencies() that returns an empty javafx.collections.ObservableList.

Specified by:

getDependencies in interface Binding<T>

Returns:

an empty ObservableList

get

public final T get()

Returns the result of computeValue(). The method computeValue() is only called if the binding is invalid. The result is cached and returned if the binding did not become invalid since the last call of get().

Returns:

the current value

onInvalidating

protected void onInvalidating()

The method onInvalidating() can be overridden by extending classes to react, if this binding becomes invalid. The default implementation is empty.

invalidate

public final void invalidate()

Description copied from interface: Binding

Mark a binding as invalid. This forces the recalculation of the value of the Binding next time it is request.

Specified by:

invalidate in interface Binding<T>

isValid

public final boolean isValid()

Description copied from interface: Binding

Checks if a binding is valid.

Specified by:

isValid in interface Binding<T>

Returns:

true if the Binding is valid, false otherwise

computeValue

protected abstract T computeValue()

Calculates the current value of this binding.

Classes extending ObjectBinding have to provide an implementation of computeValue.

Returns:

the current value

toString

public java.lang.String toString()

Returns a string representation of this ObjectBinding object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this ObjectBinding object.