Module javafx.base

Package javafx.beans.binding

Class BooleanBinding

java.lang.Object

javafx.beans.binding.BooleanExpression

javafx.beans.binding.BooleanBinding

All Implemented Interfaces:

Binding<Boolean>, Observable, ObservableBooleanValue, ObservableValue<Boolean>

public abstract class BooleanBinding
extends BooleanExpression
implements Binding<Boolean>

Base class that provides most of the functionality needed to implement a Binding of a boolean value.

BooleanBinding provides a simple invalidation-scheme. An extending class can register dependencies by calling bind(Observable...). If One of the registered dependencies becomes invalid, this BooleanBinding 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, BooleanExpression

Constructor Summary

Constructors

Constructor	Description
BooleanBinding()	Sole constructor

Method Summary

Modifier and Type	Method	Description
protected void	bind(Observable... dependencies)	Start observing the dependencies for changes.
protected abstract boolean	computeValue()	Calculates the current value of this binding.
void	dispose()	A default implementation of dispose() that is empty.
boolean	get()	Returns the result of computeValue().
ObservableList<?>	getDependencies()	A default implementation of getDependencies() that returns an empty ObservableList.
protected void	onInvalidating()	The method onInvalidating() can be overridden by extending classes to react, if this binding becomes invalid.
String	toString()	Returns a string representation of this BooleanBinding object.
protected void	unbind(Observable... dependencies)	Stop observing the dependencies for changes.

Methods declared in interface javafx.beans.binding.Binding

invalidate, isValid

Methods declared in class javafx.beans.binding.BooleanExpression

and, asObject, asString, booleanExpression, booleanExpression, isEqualTo, isNotEqualTo, not, or

Methods declared in class java.lang.Object

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

Methods declared in interface javafx.beans.Observable

addListener, removeListener

Methods declared in interface javafx.beans.value.ObservableValue

addListener, getValue, removeListener

Constructor Detail

BooleanBinding

public BooleanBinding()

Sole constructor

Method Detail

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<Boolean>

getDependencies

public ObservableList<?> getDependencies()

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

Specified by:

getDependencies in interface Binding<Boolean>

Returns:

an empty ObservableList

get

public final boolean 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().

Specified by:

get in interface ObservableBooleanValue

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.

computeValue

protected abstract boolean computeValue()

Calculates the current value of this binding.

Classes extending BooleanBinding have to provide an implementation of computeValue.

Returns:

the current value

toString

public String toString()

Returns a string representation of this BooleanBinding object.

Overrides:

toString in class Object

Returns:

a string representation of this BooleanBinding object.