JavaFX 24 · javafx.beans.binding.DoubleBinding · APIdia, the JavaDoc alternative

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

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

Below is a simple example of a DoubleBinding calculating the square- root of a javafx.beans.value.ObservableNumberValue moo.


final ObservableDoubleValue moo = ...;

DoubleBinding foo = new DoubleBinding() {

    {
        super.bind(moo);
    }

    @Override
    protected double computeValue() {
        return Math.sqrt(moo.getValue());
    }
};

Following is the same example with implementations for the optional methods Binding#getDependencies() and Binding#dispose().


final ObservableDoubleValue moo = ...;

DoubleBinding foo = new DoubleBinding() {

    {
        super.bind(moo);
    }

    @Override
    protected double computeValue() {
        return Math.sqrt(moo.getValue());
    }

    @Override
    public ObservableList<?> getDependencies() {
        return FXCollections.singletonObservableList(moo);
    }

    @Override
    public void dispose() {
        super.unbind(moo);
    }
};

Modifier and Type	Field and Description
private ExpressionHelper<Number>	helper
private BindingHelperObserver	observer Invalidation listener used for observing dependencies.
private boolean	valid
private double	value

Constructor Summary

Access	Constructor and Description
public	DoubleBinding() Creates a default `DoubleBinding`.

Method Summary

Modifier and Type	Method and Description
public void	addListener(InvalidationListener The listener to register listener) Implements javafx.beans.Observable.addListener. Adds an `InvalidationListener` which will be notified whenever the `Observable` becomes invalid.
public void	addListener(ChangeListener<? super Number> The listener to register listener) Implements javafx.beans.value.ObservableValue.addListener. Adds a `ChangeListener` which will be notified whenever the value of the `ObservableValue` changes.
protected final void	bind(Observable... the dependencies to observe dependencies) Start observing the dependencies for changes.
protected abstract double	Returns: the current value computeValue() Calculates the current value of this binding.
public void	dispose() Implements javafx.beans.binding.Binding.dispose. A default implementation of `dispose()` that is empty.
public final double	Returns: the current value get() Implements javafx.beans.value.ObservableDoubleValue.get. Returns the result of `computeValue()`.
public ObservableList<?>	Returns: an empty `ObservableList` getDependencies() Implements javafx.beans.binding.Binding.getDependencies. A default implementation of `getDependencies()` that returns an empty `javafx.collections.ObservableList`.
public final void	invalidate() Implements javafx.beans.binding.Binding.invalidate. Mark a binding as invalid.
public final boolean	isValid() Implements javafx.beans.binding.Binding.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.
public void	removeListener(InvalidationListener The listener to remove listener) Implements javafx.beans.Observable.removeListener. Removes the given listener from the list of listeners, that are notified whenever the value of the `Observable` becomes invalid.
public void	removeListener(ChangeListener<? super Number> The listener to remove listener) Implements javafx.beans.value.ObservableValue.removeListener. Removes the given listener from the list of listeners that are notified whenever the value of the `ObservableValue` changes.
public String	Returns: a string representation of this `DoubleBinding` object. toString() Overrides java.lang.Object.toString. Returns a string representation of this `DoubleBinding` object.
protected final void	unbind(Observable... the dependencies to stop observing dependencies) Stop observing the dependencies for changes.

Field Detail

helper	back to summary
private ExpressionHelper<Number> helper

observer	back to summary
private BindingHelperObserver observer Invalidation listener used for observing dependencies. This is never cleared once created as there is no way to determine when all dependencies that were previously bound were removed in one or more calls to `unbind(Observable...)`.

valid	back to summary
private boolean valid

value	back to summary
private double value

Constructor Detail

DoubleBinding	back to summary
public DoubleBinding() Creates a default `DoubleBinding`.

Method Detail

addListener back to summary

addListener	back to summary
public void addListener(InvalidationListener listener) Implements javafx.beans.Observable.addListener. Doc from javafx.beans.Observable.addListener. Adds an `InvalidationListener` which will be notified whenever the `Observable` becomes invalid. If the same listener is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness. Note that the same actual `InvalidationListener` instance may be safely registered for different `Observables`. The `Observable` stores a strong reference to the listener which will prevent the listener from being garbage collected and may result in a memory leak. It is recommended to either unregister a listener by calling `removeListener` after use or to use an instance of `WeakInvalidationListener` avoid this situation. Parameters listener:InvalidationListener The listener to register Annotations @Override

public void addListener(InvalidationListener listener)

Implements javafx.beans.Observable.addListener.

Doc from javafx.beans.Observable.addListener.

Adds an InvalidationListener which will be notified whenever the Observable becomes invalid. If the same listener is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness.

Note that the same actual InvalidationListener instance may be safely registered for different Observables.

The Observable stores a strong reference to the listener which will prevent the listener from being garbage collected and may result in a memory leak. It is recommended to either unregister a listener by calling removeListener after use or to use an instance of WeakInvalidationListener avoid this situation.

Parameters

listener:InvalidationListener: The listener to register

Annotations

@Override

addListener back to summary

addListener	back to summary
public void addListener(ChangeListener<? super Number> listener) Implements javafx.beans.value.ObservableValue.addListener. Doc from javafx.beans.value.ObservableValue.addListener. Adds a `ChangeListener` which will be notified whenever the value of the `ObservableValue` changes. If the same listener is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness. Note that the same actual `ChangeListener` instance may be safely registered for different `ObservableValues`. The `ObservableValue` stores a strong reference to the listener which will prevent the listener from being garbage collected and may result in a memory leak. It is recommended to either unregister a listener by calling `removeListener` after use or to use an instance of `WeakChangeListener` avoid this situation. Parameters listener:ChangeListener<? super Number> The listener to register Annotations @Override

public void addListener(ChangeListener<? super Number> listener)

Implements javafx.beans.value.ObservableValue.addListener.

Doc from javafx.beans.value.ObservableValue.addListener.

Adds a ChangeListener which will be notified whenever the value of the ObservableValue changes. If the same listener is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness.

Note that the same actual ChangeListener instance may be safely registered for different ObservableValues.

The ObservableValue stores a strong reference to the listener which will prevent the listener from being garbage collected and may result in a memory leak. It is recommended to either unregister a listener by calling removeListener after use or to use an instance of WeakChangeListener avoid this situation.

Parameters

listener:ChangeListener<? super Number>: The listener to register

Annotations

@Override

bind	back to summary
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:Observable[] the dependencies to observe

bind

back to summary

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:Observable[]: the dependencies to observe

computeValue back to summary

computeValue	back to summary
protected abstract double computeValue() Calculates the current value of this binding. Classes extending `DoubleBinding` have to provide an implementation of `computeValue`. Returns:double the current value

protected abstract double computeValue()

Calculates the current value of this binding.

Classes extending DoubleBinding have to provide an implementation of computeValue.

Returns:double: the current value

dispose back to summary

dispose	back to summary
public void dispose() Implements javafx.beans.binding.Binding.dispose. A default implementation of `dispose()` that is empty. Annotations @Override

public void dispose()

Implements javafx.beans.binding.Binding.dispose.

A default implementation of dispose() that is empty.

Annotations

@Override

get back to summary

get	back to summary
public final double get() Implements javafx.beans.value.ObservableDoubleValue.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:double the current value Annotations @Override

public final double get()

Implements javafx.beans.value.ObservableDoubleValue.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:double

the current value

Annotations

@Override

getDependencies back to summary

getDependencies	back to summary
public ObservableList<?> getDependencies() Implements javafx.beans.binding.Binding.getDependencies. A default implementation of `getDependencies()` that returns an empty `javafx.collections.ObservableList`. Returns:ObservableList<?> an empty `ObservableList` Annotations @Override

public ObservableList<?> getDependencies()

Implements javafx.beans.binding.Binding.getDependencies.

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

Returns:ObservableList<?>

an empty ObservableList

Annotations

@Override

invalidate back to summary

invalidate	back to summary
public final void invalidate() Implements javafx.beans.binding.Binding.invalidate. Doc from javafx.beans.binding.Binding.invalidate. Mark a binding as invalid. This forces the recalculation of the value of the `Binding` next time it is request. Annotations @Override

public final void invalidate()

Implements javafx.beans.binding.Binding.invalidate.

Doc from javafx.beans.binding.Binding.invalidate.

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

Annotations

@Override

isValid back to summary

isValid	back to summary
public final boolean isValid() Implements javafx.beans.binding.Binding.isValid. Doc from javafx.beans.binding.Binding.isValid. Checks if a binding is valid. Returns:boolean `true` if the `Binding` is valid, `false` otherwise Annotations @Override

public final boolean isValid()

Implements javafx.beans.binding.Binding.isValid.

Doc from javafx.beans.binding.Binding.isValid.

Checks if a binding is valid.

Returns:boolean

true if the Binding is valid, false otherwise

Annotations

@Override

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

removeListener back to summary

removeListener	back to summary
public void removeListener(InvalidationListener listener) Implements javafx.beans.Observable.removeListener. Doc from javafx.beans.Observable.removeListener. Removes the given listener from the list of listeners, that are notified whenever the value of the `Observable` becomes invalid. If the given listener has not been previously registered (i.e. it was never added) then this method call is a no-op. If it had been previously added then it will be removed. If it had been added more than once, then only the first occurrence will be removed. Parameters listener:InvalidationListener The listener to remove Annotations @Override

public void removeListener(InvalidationListener listener)

Implements javafx.beans.Observable.removeListener.

Doc from javafx.beans.Observable.removeListener.

Removes the given listener from the list of listeners, that are notified whenever the value of the Observable becomes invalid.

If the given listener has not been previously registered (i.e. it was never added) then this method call is a no-op. If it had been previously added then it will be removed. If it had been added more than once, then only the first occurrence will be removed.

Parameters

listener:InvalidationListener: The listener to remove

Annotations

@Override

removeListener back to summary

removeListener	back to summary
public void removeListener(ChangeListener<? super Number> listener) Implements javafx.beans.value.ObservableValue.removeListener. Doc from javafx.beans.value.ObservableValue.removeListener. Removes the given listener from the list of listeners that are notified whenever the value of the `ObservableValue` changes. If the given listener has not been previously registered (i.e. it was never added) then this method call is a no-op. If it had been previously added then it will be removed. If it had been added more than once, then only the first occurrence will be removed. Parameters listener:ChangeListener<? super Number> The listener to remove Annotations @Override

public void removeListener(ChangeListener<? super Number> listener)

Implements javafx.beans.value.ObservableValue.removeListener.

Doc from javafx.beans.value.ObservableValue.removeListener.

Removes the given listener from the list of listeners that are notified whenever the value of the ObservableValue changes.

Parameters

listener:ChangeListener<? super Number>: The listener to remove

Annotations

@Override

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns a string representation of this `DoubleBinding` object. Returns:String a string representation of this `DoubleBinding` object. Annotations @Override

public String toString()

Overrides java.lang.Object.toString.

Returns a string representation of this DoubleBinding object.

Returns:String

a string representation of this DoubleBinding object.

Annotations

@Override

unbind	back to summary
protected final void unbind(Observable... dependencies) Stop observing the dependencies for changes. Parameters dependencies:Observable[] the dependencies to stop observing

unbind

back to summary

protected final void unbind(Observable... dependencies)

Stop observing the dependencies for changes.

Parameters

dependencies:Observable[]: the dependencies to stop observing

public abstract Class DoubleBinding

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail