Module javafx.base

Package javafx.beans.binding

Interface Binding<T>

Type Parameters:

T - the type of the wrapped value

All Superinterfaces:

Observable, ObservableValue<T>

All Known Subinterfaces:

NumberBinding

All Known Implementing Classes:

BooleanBinding, DoubleBinding, FloatBinding, IntegerBinding, ListBinding, LongBinding, MapBinding, ObjectBinding, SetBinding, StringBinding

public interface Binding<T>
extends ObservableValue<T>

A Binding calculates a value that depends on one or more sources. The sources are usually called the dependency of a binding. A binding observes its dependencies for changes and updates its value automatically.

While a dependency of a binding can be anything, it is almost always an implementation of ObservableValue. Binding implements ObservableValue allowing to use it in another binding. With that one can assemble very complex bindings from simple bindings.

All bindings in the JavaFX runtime are calculated lazily. That means, if a dependency changes, the result of a binding is not immediately recalculated, but it is marked as invalid. Next time the value of an invalid binding is requested, it is recalculated.

It is recommended to use one of the base classes defined in this package (e.g. DoubleBinding) to define a custom binding, because these classes already provide most of the needed functionality. See DoubleBinding for an example.

Since:

JavaFX 2.0

See Also:

• DoubleBinding

Method Summary

Modifier and Type	Method	Description
void	dispose()	Signals to the Binding that it will not be used anymore and any references can be removed.
ObservableList<?>	getDependencies()	Returns the dependencies of a binding in an unmodifiable ObservableList.
void	invalidate()	Mark a binding as invalid.
boolean	isValid()	Checks if a binding is valid.

Methods declared in interface javafx.beans.Observable

addListener, removeListener, subscribe

Methods declared in interface javafx.beans.value.ObservableValue

addListener, flatMap, getValue, map, orElse, removeListener, subscribe, subscribe, when

Method Details

isValid

boolean isValid()

Checks if a binding is valid.

Returns:

true if the Binding is valid, false otherwise

invalidate

void invalidate()

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

getDependencies

ObservableList<?> getDependencies()

Returns the dependencies of a binding in an unmodifiable ObservableList. The implementation is optional. The main purpose of this method is to support developers during development. It allows to explore and monitor dependencies of a binding during runtime.

Because this method should not be used in production code, it is recommended to implement this functionality as sparse as possible. For example if the dependencies do not change, each call can generate a new ObservableList, avoiding the necessity to store the result.

Returns:

an unmodifiable ObservableList of the dependencies

dispose

void dispose()

Signals to the Binding that it will not be used anymore and any references can be removed. A call of this method usually results in the binding stopping to observe its dependencies by unregistering its listener(s). The implementation is optional.

All bindings in our implementation use instances of WeakInvalidationListener, which means usually a binding does not need to be disposed. But if you plan to use your application in environments that do not support WeakReferences you have to dispose unused Bindings to avoid memory leaks.