Package org.jdesktop.swingbinding

Class JListBinding<E,​SS,​TS>

  • Type Parameters:
    E - the type of elements in the source List
    SS - the type of source object (on which the source property resolves to List)
    TS - the type of target object (on which the target property resolves to JList)
    public final class JListBinding<E,​SS,​TS>
extends AutoBinding<SS,​List<E>,​TS,​List>
    Binds a List of objects to act as the elements of a JList. Each object in the source List provides one element in the JList. By setting a DetailBinding you can specify the property to use to derive each list element from its corresponding object in the source List. The default DetailBinding uses the objects directly. Instances of JListBinding are obtained by calling one of the createJListBinding methods in the SwingBindings class.

    Here is an example of creating a binding from a List of Person objects to a JList: 

    
    // create the person list
    List people = createPersonList();

    // create the binding from List to JList
    JListBinding lb = SwingBindings.createJListBinding(READ, people, jList);

    // define the property to be used to derive list elements
    ELProperty fullNameP = ELProperty.create("${firstName} ${lastName}");

    // add the detail binding
    lb.setDetailBinding(fullNameP);

    // realize the binding
    lb.bind();

    The JList target of a JListBinding acts as a live view of the objects in the source List, regardless of the update strategy (the meaning of the update strategy is clarified later in this document). JListBinding listens to the property specified for any DetailBinding, for all objects in the List, and updates the values displayed in the JList in response to change. If the List is an instance of ObservableList, then changes to the List contents (such as adding, removing or replacing an object) are also reflected in the JList. Important: Changing the contents of a non-observable List while it is participating in a JListBinding is unsupported, resulting in undefined behavior and possible exceptions.

    JListBinding requires extra clarification on the operation of the refresh and save methods and the meaning of the update strategy. The target property of a JListBinding is not the target JList property provided in the constructor, but rather a private synthetic property representing the List of objects to show in the target JList. This synthetic property is readable/writeable only when the JListBinding is bound and the target JList property is readable with a non-null value.

    It is this private synthetic property on which the refresh and save methods operate; meaning that these methods simply cause syncing between the value of the source List property and the value of the synthetic target property (representing the List to be shown in the target JList). These methods do not, therefore, have anything to do with refreshing values in the JList. Likewise, the update strategy, which simply controls when refresh and save are automatically called, also has nothing to do with refreshing values in the JList.

    Note: At the current time, the READ_WRITE update strategy is not useful for JListBinding. To prevent unwanted confusion, READ_WRITE is translated to READ by JListBinding's constructor.

    JListBinding works by installing a custom model on the target JList, as appropriate, to represent the source List. The model is installed on a target JList with the first succesful call to refresh with that JList as the target. Subsequent calls to refresh update the elements in this already-installed model. The model is uninstalled from a target JList when either the JListBinding is unbound or when the target JList property changes to no longer represent that JList. Note: When the model is uninstalled from a JList, it is replaced with a DefaultListModel, in order to leave the JList functional.

    Some of the above is easier to understand with an example. Let's consider a JListBinding (binding), with update strategy READ, between a property representing a List (listP) and a property representing a JList (jListP). listP and jListP both start off readable, referring to a non-null List and non-null JList respectively. Let's look at what happens for each of a sequence of events:

    SequenceEventResult
    1 explicit call to binding.bind() - synthetic target property becomes readable/writeable
    - refresh() is called
    - model is installed on target JList, representing list of objects
    2 listP changes to a new List - refresh() is called
    - model is updated with new list of objects
    3 jListP changes to a new JList - model is uninstalled from old JList
    4 explicit call to binding.refresh() - model is installed on target JList, representing list of objects
    5 listP changes to a new List - refresh() is called
    - model is updated with new list of objects
    6 explicit call to binding.unbind() - model is uninstalled from target JList

    Notice that in step 3, when the value of the JList property changed, the new JList did not automatically get the model with the elements applied to it. A change to the target value should not cause an AutoBinding to sync the target from the source. Step 4 forces a sync by explicitly calling refresh. Alternatively, it could be caused by any other action that results in a refresh (for example, the source property changing value, or an explicit call to unbind followed by bind).

    DetailBindings are managed by the JList. They are not to be explicitly bound, unbound, added to a BindingGroup, or accessed in a way that is not allowed for a managed binding.

    In addition to binding the elements of a JList, it is possible to bind to the selection of a JList. When binding to the selection of a JList backed by a JListBinding, the selection is always in terms of elements from the source List, regardless of any DetailBinding specified. See the list of interesting swing properties in the package summary for more details.

    Author:
    Shannon Hickey

    • Constructor Detail

      • JListBinding

        protected JListBinding​(AutoBinding.UpdateStrategy strategy,
                       SS sourceObject,
                       Property<SS,​List<E>> sourceListProperty,
                       TS targetObject,
                       Property<TS,​? extends JList> targetJListProperty,
                       String name)
        Constructs an instance of JListBinding.
        Parameters:
        strategy - the update strategy
        sourceObject - the source object
        sourceListProperty - a property on the source object that resolves to the List of elements
        targetObject - the target object
        targetJListProperty - a property on the target object that resolves to a JList
        name - a name for the JListBinding
        Throws:
        IllegalArgumentException - if the source property or target property is null

    • Method Detail

      • setDetailBinding

        public JListBinding.DetailBinding setDetailBinding​(Property<E,​?> detailProperty)
        Creates a DetailBinding and sets it as the DetailBinding for this JListBinding. A DetailBinding specifies the property of the objects in the source List to be used as the elements of the JList. If the detailProperty parameter is null, the DetailBinding specifies that the objects themselves be used.
        Parameters:
        detailProperty - the property with which to derive each list value from its corresponding object in the source List
        Returns:
        the DetailBinding

      • setDetailBinding

        public JListBinding.DetailBinding setDetailBinding​(Property<E,​?> detailProperty,
                                                   String name)
        Creates a named DetailBinding and sets it as the DetailBinding for this JListBinding. A DetailBinding specifies the property of the objects in the source List to be used as the elements of the JList. If the detailProperty parameter is null, the DetailBinding specifies that the objects themselves be used.
        Parameters:
        detailProperty - the property with which to derive each list value from its corresponding object in the source List
        Returns:
        the DetailBinding

      • getDetailBinding

        public JListBinding.DetailBinding getDetailBinding()
        Returns the DetailBinding for this JListBinding. A DetailBinding specifies the property of the source List elements to be used as the elements of the JList.
        Returns:
        the DetailBinding
        See Also:
        setDetailBinding(Property, String)