Properties and Binding

Properties
and
Binding
Dr. Ahmad Zaeri
Faculty of Computer Engineering
University of Isfahan

JavaBean
• Default Constructor
• Property
• Private Field
• Setter
• Getter
• Use Naming Conventions !
2

JavaFX Property
• A class that contains properties with some new method naming conventions !
Returns the current value
of the amountDue property
Set the value property
of the amountDue property
New convention !
Returns the amountDue property itself !
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Built-in Properties
• javafx.beans.property.*
• Classes, which end in “Property”
• Classes that all have the ability to be bound
IntegerProperty
BooleanProperty
StringProperty
ListProperty
ObjectProperty
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Binding
• When objects participate in bindings, changes made to one object will
automatically be reflected in another object.
• To synchronize changes between two values.
• There are many types of binding so …
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• High level :
• Fluent API
Types of binding
• A Simple Approach
• Binding Class
• High/Low level :
a simple way to create bindings
• ChangeListener Interface
• InvalidationListener Interface
• Low level :
• Using one of the binding classes and overriding its computeValue()
method
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High Level :
A Simple Approach …
• Unidirectional Binding:
Direct change in x causes exception!
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High Level :
A Simple Approach …(cont’d)
• Bidirectional Binding
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High Level:
Fluent API
Exposes methods on the various dependency objects .
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High Level:
Bindings Class
Provides static factory methods.
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Key interfaces of the
JavaFX properties and bindings framework
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Key interfaces of the
JavaFX properties and bindings framework(cont’d
• The Observable interface fires the change notifications
and
the InvalidationListener interface receives them.
• The ObservableValue interface fires the change notifications
and
the ChangeListener interface receives them.
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High/Low Level :
Eagerly…
Add a change listener to be notified when the property's value has changed.
See slide 3 !
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High/Low Level :
Lazily…
• By changing the value of a property, the binding becomes invalid, and the
invalidation listener will fire.
• When a change occurs, the value is not immediately recomputed.
• Recomputation happens later, if and when the value is subsequently requested.
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High/Low Level :
Lazily…
Makes the binding invalid
The binding is now invalid
The binding is now invalid
Make the binding valid
Make invalid …
Make valid …
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Low Level:
This allows the developer to use primitives and more-complex math operations.
• Use a derived NumberBinding class such as a DoubleBinding class.
• Override its computeValue() method
• you can use the familiar operators such as * and - to formulate complex
math equations:
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Low Level:
Example …
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Another Example …
See BindingExpressions.java Example in the “Properties and
Binding” package.
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Now let’s see Binding in
LogEdit !
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Resources
• JavaFX Properties and Binding Tutorial, Release 8
• JavaFX 2.0 Introduction By Example
• Pro JavaFX 2.0
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