- java.lang.Object
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- javafx.beans.binding.NumberExpressionBase
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- javafx.beans.binding.DoubleExpression
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- javafx.beans.binding.DoubleBinding
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- All Implemented Interfaces:
Binding<Number>
,NumberBinding
,NumberExpression
,Observable
,ObservableDoubleValue
,ObservableNumberValue
,ObservableValue<Number>
public abstract class DoubleBinding extends DoubleExpression implements NumberBinding
Base class that provides most of the functionality needed to implement aBinding
of adouble
value.DoubleBinding
provides a simple invalidation-scheme. An extending class can register dependencies by callingbind(Observable...)
. If One of the registered dependencies becomes invalid, thisDoubleBinding
is marked as invalid. Withunbind(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 whenget()
is called for an invalid binding.Below is a simple example of a
DoubleBinding
calculating the square- root of aObservableNumberValue
moo
.final ObservableDoubleValue moo = ...; DoubleBinding foo = new DoubleBinding() { { super.bind(moo); } @Override protected double computeValue() { return Math.sqrt(moo.getValue()); } };
Binding.getDependencies()
andBinding.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); } };
- Since:
- JavaFX 2.0
- See Also:
Binding
,NumberBinding
,DoubleExpression
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Constructor Summary
Constructors Constructor Description DoubleBinding()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description 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 ofdispose()
that is empty.double
get()
Returns the result ofcomputeValue()
.ObservableList<?>
getDependencies()
A default implementation ofgetDependencies()
that returns an emptyObservableList
.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 thisDoubleBinding
object.protected void
unbind(Observable... dependencies)
Stop observing the dependencies for changes.-
Methods declared in interface javafx.beans.binding.Binding
invalidate, isValid
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Methods declared in class javafx.beans.binding.DoubleExpression
asObject, doubleExpression, doubleExpression
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Methods declared in interface javafx.beans.binding.NumberExpression
add, 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, subtract
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Methods declared in class javafx.beans.binding.NumberExpressionBase
numberExpression
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Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Methods declared in interface javafx.beans.Observable
addListener, removeListener
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Methods declared in interface javafx.beans.value.ObservableNumberValue
doubleValue, floatValue, intValue, longValue
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Methods declared in interface javafx.beans.value.ObservableValue
addListener, getValue, removeListener
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Method Detail
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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
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unbind
protected final void unbind(Observable... dependencies)
Stop observing the dependencies for changes.- Parameters:
dependencies
- the dependencies to stop observing
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dispose
public void dispose()
A default implementation ofdispose()
that is empty.
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getDependencies
public ObservableList<?> getDependencies()
A default implementation ofgetDependencies()
that returns an emptyObservableList
.- Specified by:
getDependencies
in interfaceBinding<Number>
- Returns:
- an empty
ObservableList
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get
public final double get()
Returns the result ofcomputeValue()
. The methodcomputeValue()
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 ofget()
.- Specified by:
get
in interfaceObservableDoubleValue
- Returns:
- the current value
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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.
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computeValue
protected abstract double computeValue()
Calculates the current value of this binding.Classes extending
DoubleBinding
have to provide an implementation ofcomputeValue
.- Returns:
- the current value
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