JavaFX 24 · com.sun.javafx.binding.FlatMappedBinding

A binding holding the value of an indirect source. The indirect source results from applying a mapping to the given source.

Implementation:

In a flat mapped binding there are always two subscriptions involved:

The subscription on its source
The subscription on the value resulting from the mapping of the source: the indirect source

The subscription on its given source is present when this binding itself is observed and not present otherwise.

The subscription on the indirect source must change whenever the value of the given source changes or is invalidated. More specifically, when the given source is invalidated the indirect subscription should be removed, and when it is revalidated it should resubscribe to the newly calculated indirect source. The binding avoids resubscribing when only the value of the indirect source changes.

Field Summary

Modifier and Type	Field and Description
private ObservableValue<? extends T>	indirectSource
private Subscription	indirectSourceSubscription
private final Function<? super S, ? extends ObservableValue<? extends T>>	mapper
private final ObservableValue<S>	source

Access	Constructor and Description
public	FlatMappedBinding(ObservableValue<S> source, Function<? super S, ? extends ObservableValue<? extends T>> mapper)

Method Summary

Modifier and Type	Method and Description
protected T	computeValue() Implements abstract javafx.beans.binding.ObjectBinding.computeValue. Calculates the current value of this binding.
private void	invalidateAll() Called when the primary source changes.
protected Subscription	observeSources() Implements abstract com.sun.javafx.binding.LazyObjectBinding.observeSources. Called when this binding was previously not observed and a new observer was added.
private void	unsubscribeIndirectSource()

Inherited from com.sun.javafx.binding.LazyObjectBinding:: addListener addListener allowValidation removeListener removeListener

Field Detail

indirectSource	back to summary
private ObservableValue<? extends T> indirectSource

indirectSourceSubscription	back to summary
private Subscription indirectSourceSubscription

mapper	back to summary
private final Function<? super S, ? extends ObservableValue<? extends T>> mapper

source	back to summary
private final ObservableValue<S> source

Constructor Detail

FlatMappedBinding	back to summary
public FlatMappedBinding(ObservableValue<S> source, Function<? super S, ? extends ObservableValue<? extends T>> mapper)

Method Detail

computeValue back to summary

computeValue	back to summary
protected T computeValue() Implements abstract javafx.beans.binding.ObjectBinding.computeValue. Doc from javafx.beans.binding.ObjectBinding.computeValue. Calculates the current value of this binding. Classes extending `ObjectBinding` have to provide an implementation of `computeValue`. Returns:T the current value Annotations @Override

protected T computeValue()

Implements abstract javafx.beans.binding.ObjectBinding.computeValue.

Doc from javafx.beans.binding.ObjectBinding.computeValue.

Calculates the current value of this binding.

Classes extending ObjectBinding have to provide an implementation of computeValue.

Returns:T

the current value

Annotations

@Override

invalidateAll back to summary

invalidateAll	back to summary
private void invalidateAll() Called when the primary source changes. Invalidates this binding and unsubscribes the indirect source to avoid holding a strong reference to it. If the binding becomes valid later, `computeValue()` will subscribe to a newly calculated indirect source. Note that this only needs to be called for changes of the primary source; changes in the indirect source only need to invalidate this binding without also unsubscribing, as it would be wasteful to resubscribe to the same indirect source for each invalidation of that source.

private void invalidateAll()

Called when the primary source changes. Invalidates this binding and unsubscribes the indirect source to avoid holding a strong reference to it. If the binding becomes valid later, computeValue() will subscribe to a newly calculated indirect source.

Note that this only needs to be called for changes of the primary source; changes in the indirect source only need to invalidate this binding without also unsubscribing, as it would be wasteful to resubscribe to the same indirect source for each invalidation of that source.

observeSources back to summary

observeSources	back to summary
protected Subscription observeSources() Implements abstract com.sun.javafx.binding.LazyObjectBinding.observeSources. Doc from com.sun.javafx.binding.LazyObjectBinding.observeSources. Called when this binding was previously not observed and a new observer was added. Implementors must return a `Subscription` which will be cancelled when this binding no longer has any observers. Returns:Subscription a `Subscription` which will be cancelled when this binding no longer has any observers, never null Annotations @Override

protected Subscription observeSources()

Implements abstract com.sun.javafx.binding.LazyObjectBinding.observeSources.

Doc from com.sun.javafx.binding.LazyObjectBinding.observeSources.

Called when this binding was previously not observed and a new observer was added. Implementors must return a Subscription which will be cancelled when this binding no longer has any observers.

Returns:Subscription

a Subscription which will be cancelled when this binding no longer has any observers, never null