public abstract class DoubleBinding extends DoubleExpression implements NumberBinding
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 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);
}
};
Binding,
NumberBinding,
DoubleExpression| Constructor and Description |
|---|
DoubleBinding() |
| Modifier and Type | Method and Description |
|---|---|
void |
addListener(ChangeListener<? super Number> listener)
Adds a
ChangeListener which will be notified whenever the value
of the ObservableValue changes. |
void |
addListener(InvalidationListener listener)
Adds an
InvalidationListener which will be notified whenever the
Observable becomes invalid. |
protected void |
bind(Observable... dependencies)
Start observing the dependencies for changes.
|
protected abstract double |
computeValue()
Calculates the current value of this binding.
|
void |
dispose()
A default implementation of
dispose() that is empty. |
double |
get()
Returns the result of
computeValue(). |
ObservableList<?> |
getDependencies()
A default implementation of
getDependencies() that returns an
empty 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(ChangeListener<? super Number> listener)
Removes the given listener from the list of listeners, that are notified
whenever the value of the
ObservableValue changes. |
void |
removeListener(InvalidationListener listener)
Removes the given listener from the list of listeners, that are notified
whenever the value of the
Observable becomes invalid. |
String |
toString()
Returns a string representation of this
DoubleBinding object. |
protected void |
unbind(Observable... dependencies)
Stop observing the dependencies for changes.
|
add, add, add, add, add, asObject, divide, divide, divide, divide, divide, doubleExpression, doubleExpression, doubleValue, floatValue, getValue, intValue, longValue, multiply, multiply, multiply, multiply, multiply, negate, subtract, subtract, subtract, subtract, subtractasString, asString, asString, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, lessThan, lessThan, lessThan, lessThan, lessThan, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, numberExpressionclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitadd, add, add, add, add, asString, asString, asString, divide, divide, divide, divide, divide, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, greaterThanOrEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, isNotEqualTo, lessThan, lessThan, lessThan, lessThan, lessThan, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, lessThanOrEqualTo, multiply, multiply, multiply, multiply, multiply, negate, subtract, subtract, subtract, subtract, subtractdoubleValue, floatValue, intValue, longValuegetValuepublic void addListener(InvalidationListener listener)
ObservableInvalidationListener 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.
addListener in interface Observablelistener - The listener to registerObservable.removeListener(InvalidationListener)public void removeListener(InvalidationListener listener)
ObservableObservable 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.
removeListener in interface Observablelistener - The listener to removeObservable.addListener(InvalidationListener)public void addListener(ChangeListener<? super Number> listener)
ObservableValueChangeListener 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.
addListener in interface ObservableValue<Number>listener - The listener to registerObservableValue.removeListener(ChangeListener)public void removeListener(ChangeListener<? super Number> listener)
ObservableValueObservableValue 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.
removeListener in interface ObservableValue<Number>listener - The listener to removeObservableValue.addListener(ChangeListener)protected final void bind(Observable... dependencies)
dependencies - the dependencies to observeprotected final void unbind(Observable... dependencies)
dependencies - the dependencies to stop observingpublic void dispose()
dispose() that is empty.public ObservableList<?> getDependencies()
getDependencies() that returns an
empty ObservableList.getDependencies in interface Binding<Number>ObservableListpublic final double get()
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().get in interface ObservableDoubleValueprotected void onInvalidating()
public final void invalidate()
BindingBinding next time it is request.invalidate in interface Binding<Number>public final boolean isValid()
Bindingprotected abstract double computeValue()
Classes extending DoubleBinding have to provide an implementation
of computeValue.
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