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## com.jgoodies.binding.extras
Class SelectionInList2

    java.lang.Object
      com.jgoodies.binding.beans.Model
          com.jgoodies.binding.list.ListHolder
              com.jgoodies.binding.extras.SelectionInList2

All Implemented Interfaces:
  Observable, Serializable, ListModel

    public final class SelectionInList2

extends ListHolder

Represents a selection in a List. Provides bound bean properties for the list, the selection, the selection index, and the selection empty state. Selection changes fire an event only if the old and new value are not equal. If you need to compare the identity you can use and observe the selection index instead of the selection or value.

Note: This class is not yet part of the binary Binding library; it comes with the Binding distributions as an extra. The API is work in progress and may change without notice; this class may even be completely removed from future distributions. If you want to use this class, you may consider copying it into your codebase.

The SelectionInList2 uses three ValueModels to hold the list, the selection and selection index and provides bound bean properties for these models. You can access, observe and replace these ValueModels. This is useful to connect a SelectionInList2 with other ValueModels; for example you can use the SelectionInList2's selection holder as bean channel for a PresentationModel. See the Binding tutorial classes for examples on how to connect a SelectionInList2 with a PresentationModel.

This class also implements the `ListModel` interface that allows API users to observe fine grained changes in the structure and contents of the list. Hence instances of this class can be used directly as model of a JList. If you want to use a SelectionInList2 with a JComboBox or JTable, you can convert the SelectionInList2 to the associated component model interfaces using the adapter classes `ComboBoxAdapter` and `AbstractTableAdapter` respectively. These classes are part of the Binding library too.

Unlike the older SelectionInList, the SelectionInList2 supports only `List`s as content of its List holder. The SelectionInListModel supports `ListModel`s as content of its ListModel holder. The SelectionInList2 and SelectionInListModel differ in how precise they can fire events about changes to the content and structure of the underlying List or ListModel content. The SelectionInList2 can only report that the List changes completely; this is done by emitting a PropertyChangeEvent for the list property. Also, a `ListDataEvent` is fired that reports a complete change. The SelectionInListModel reports the same PropertyChangeEvent. But fine grained changes in the ListModel will be forwarded as fine grained changes in the content, added and removed elements.

If the List or ListModel content doesn't change at all, or if it always changes completely, there's no differences between the SelectionInListModel and the SelectionInList2. But if the list structure or content changes, the ListModel reports more fine grained events to registered ListDataListeners, which in turn allows list views to chooser better user interface gestures: for example, a table with scroll pane may retain the current selection and scroll offset.

An example for the benefit of fine grained ListDataEvents is the asynchronous transport of list elements from a server to a client. Let's say you transport the list elements in portions of 10 elements to improve the application's responsiveness. The user can then work with the SelectionInListModel as soon as the ListModel gets populated. If at a later time more elements are added to the ListModel, the SelectionInListModel can retain the selection index (and selection) and will just report a ListDataEvent about the interval added. JList, JTable and JComboBox will then just add the new elements at the end of the list presentation.

If you want to combine List operations and the ListModel change reports, you may consider using an implementation that combines these two interfaces, for example `ArrayListModel` or `LinkedListModel`.

This binding library provides some help for firing PropertyChangeEvents if the old ListModel and new ListModel are equal but not the same. Class `ExtendedPropertyChangeSupport` allows to permanently or individually check the identity (using `==`) instead of checking the equity (using `#equals`). Class `Model` uses this extended property change support. And class `ValueHolder` uses it too and can be configured to always test the identity.

This class inherits public convenience methods for firing ListDataEvents, see the methods `#fireContentsChanged`, `#fireIntervalAdded`, and `#fireIntervalRemoved`. These are automatically invoked if the list holder holds a ListModel that fires these events. If on the other hand the underlying List or ListModel does not fire a required ListDataEvent, you can use these methods to notify presentations about a change. It is recommended to avoid sending duplicate ListDataEvents; hence check if the underlying ListModel fires the necessary events or not. Typically an underlying ListModel will fire the add and remove events; but often it'll lack an event if the (seletcted) contents has changed. A convenient way to indicate that change is `#fireSelectedContentsChanged`. See the tutorial's AlbumManagerModel for an example how to use this feature.

Constraints: The list holder holds instances of `List`, the selection holder values of type `Object` and the selection index holder of type `Integer`. The selection index holder must hold non-null index values; however, when firing an index value change event, both the old and new value may be null. If the ListModel changes, the underyling ValueModel must fire a PropertyChangeEvent.

Since:
  1.1
Version:
  $Revision: 1.5 $
Author:
  Karsten Lentzsch
See Also:
  `SelectionInListModel`, `ValueModel`, `List`, `ListModel`, `ComboBoxAdapter`, `AbstractTableAdapter`, `ExtendedPropertyChangeSupport`, `Model`, `ValueHolder`, Serialized Form

Field Summary
`static String` | `PROPERTYNAME_SELECTION` The name of the bound read-write selection property.
`static String` | `PROPERTYNAME_SELECTION_EMPTY` The name of the bound read-only selectionEmpty property.
`static String` | `PROPERTYNAME_SELECTION_HOLDER` The name of the bound read-write selection holder property.
`static String` | `PROPERTYNAME_SELECTION_INDEX` The name of the bound read-write selectionIndex property.
`static String` | `PROPERTYNAME_SELECTION_INDEX_HOLDER` The name of the bound read-write selection index holder property.

Fields inherited from class com.jgoodies.binding.list.ListHolder
`list, PROPERTYNAME_LIST, PROPERTYNAME_LIST_HOLDER`

Constructor Summary
`SelectionInList2()` Constructs a SelectionInList2 with an empty initial ArrayList using defaults for the selection holder and selection index holder.
`SelectionInList2(List list)` Constructs a SelectionInList2 on the given List using defaults for the selection holder and selection index holder.
`SelectionInList2(List list, ValueModel selectionHolder)` Constructs a SelectionInList2 on the given List and selection holder using a default selection index holder.
`SelectionInList2(List list, ValueModel selectionHolder, ValueModel selectionIndexHolder)` Constructs a SelectionInList2 on the given List, selection holder, and selection index holder.
`SelectionInList2(Object[] listItems)` Constructs a SelectionInList2 on the given item array using defaults for the selection holder and selection index holder.
`SelectionInList2(Object[] listItems, ValueModel selectionHolder)` Constructs a SelectionInList2 on the given item array and selection holder using a default selection index holder.
`SelectionInList2(Object[] listItems, ValueModel selectionHolder, ValueModel selectionIndexHolder)` Constructs a SelectionInList2 on the given item array and selection holder using a default selection index holder.
`SelectionInList2(ValueModel listHolder)` Constructs a SelectionInList2 on the given list holder using defaults for the selection holder and selection index holder.
`SelectionInList2(ValueModel listHolder, ValueModel selectionHolder)` Constructs a SelectionInList2 on the given list holder, selection holder and selection index holder.
`SelectionInList2(ValueModel listHolder, ValueModel selectionHolder, ValueModel selectionIndexHolder)` Constructs a SelectionInList2 on the given list holder, selection holder and selection index holder.

Method Summary
`void` | `clearSelection()` Clears the selection of this SelectionInList2 - if any.
`void` | `fireSelectedContentsChanged()` Notifies all registered ListDataListeners that the contents of the selected list item - if any - has changed.
`Object` | `getSelection()` Looks up and returns the current selection using the current selection index.
`ValueModel` | `getSelectionHolder()` Returns the selection holder.
`int` | `getSelectionIndex()` Returns the selection index.
`ValueModel` | `getSelectionIndexHolder()` Returns the selection index holder.
`boolean` | `hasSelection()` Checks and answers if an element is selected.
`boolean` | `isSelectionEmpty()` Checks and answers whether the selection is empty or not.
`void` | `setSelection(Object newSelection)` Sets the first list element that equals the given new selection as new selection.
`void` | `setSelectionHolder(ValueModel newSelectionHolder)` Sets a new selection holder.
`void` | `setSelectionIndex(int newSelectionIndex)` Sets a new selection index.
`void` | `setSelectionIndexHolder(ValueModel newSelectionIndexHolder)` Sets a new selection index holder.
`protected void` | `updateList(List oldList, List newList)` Updates the selection index and fires a property change for the list and a contents change event.

Methods inherited from class com.jgoodies.binding.list.ListHolder
`addListDataListener, fireContentsChanged, fireIntervalAdded, fireIntervalRemoved, fireListChanged, getElementAt, getList, getListDataListeners, getListHolder, getSize, getSize, isEmpty, removeListDataListener, setList, setListHolder`

Methods inherited from class com.jgoodies.binding.beans.Model
`addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, equals, fireMulticastPropertyChange, fireMultiplePropertiesChanged, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, fireVetoableChange, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### PROPERTYNAME_SELECTION

    public static final String PROPERTYNAME_SELECTION

  The name of the bound read-write selection property.

  See Also:
    Constant Field Values

### PROPERTYNAME_SELECTION_EMPTY

    public static final String PROPERTYNAME_SELECTION_EMPTY

  The name of the bound read-only selectionEmpty property.

  See Also:
    Constant Field Values

### PROPERTYNAME_SELECTION_HOLDER

    public static final String PROPERTYNAME_SELECTION_HOLDER

  The name of the bound read-write selection holder property.

  See Also:
    Constant Field Values

### PROPERTYNAME_SELECTION_INDEX

    public static final String PROPERTYNAME_SELECTION_INDEX

  The name of the bound read-write selectionIndex property.

  See Also:
    Constant Field Values

### PROPERTYNAME_SELECTION_INDEX_HOLDER

    public static final String PROPERTYNAME_SELECTION_INDEX_HOLDER

  The name of the bound read-write selection index holder property.

  See Also:
    Constant Field Values

Constructor Detail

### SelectionInList2

    public SelectionInList2()

  Constructs a SelectionInList2 with an empty initial ArrayList using defaults for the selection holder and selection index holder.

### SelectionInList2

    public SelectionInList2(Object[] listItems)

  Constructs a SelectionInList2 on the given item array using defaults for the selection holder and selection index holder. The specified array will be converted to a List.

  Changes to the list "write through" to the array, and changes to the array contents will be reflected in the list.

  Parameters:
    `listItems` - the array of initial items
  Throws:
    `NullPointerException` - if `listItems` is `null`

### SelectionInList2

    public SelectionInList2(Object[] listItems,
                            ValueModel selectionHolder)

  Constructs a SelectionInList2 on the given item array and selection holder using a default selection index holder. The specified array will be converted to a List.

  Changes to the list "write through" to the array, and changes to the array contents will be reflected in the list.

  Parameters:
    `listItems` - the array of initial items
    `selectionHolder` - holds the selection
  Throws:
    `NullPointerException` - if `listItems` or `selectionHolder` is `null`

### SelectionInList2

    public SelectionInList2(Object[] listItems,
                            ValueModel selectionHolder,
                            ValueModel selectionIndexHolder)

  Constructs a SelectionInList2 on the given item array and selection holder using a default selection index holder. The specified array will be converted to a List.

  Changes to the list "write through" to the array, and changes to the array contents will be reflected in the list.

  Parameters:
    `listItems` - the array of initial items
    `selectionHolder` - holds the selection
    `selectionIndexHolder` - holds the selection index
  Throws:
    `NullPointerException` - if `listItems`, `selectionHolder`, or `selectionIndexHolder` is `null`

### SelectionInList2

    public SelectionInList2(List list)

  Constructs a SelectionInList2 on the given List using defaults for the selection holder and selection index holder.

  Parameters:
    `list` - the initial list

### SelectionInList2

    public SelectionInList2(List list,
                            ValueModel selectionHolder)

  Constructs a SelectionInList2 on the given List and selection holder using a default selection index holder.

  Parameters:
    `list` - the initial list
    `selectionHolder` - holds the selection
  Throws:
    `NullPointerException` - if `selectionHolder` is `null`

### SelectionInList2

    public SelectionInList2(List list,
                            ValueModel selectionHolder,
                            ValueModel selectionIndexHolder)

  Constructs a SelectionInList2 on the given List, selection holder, and selection index holder.

  Parameters:
    `list` - the initial list
    `selectionHolder` - holds the selection
    `selectionIndexHolder` - holds the selection index
  Throws:
    `NullPointerException` - if `selectionHolder`, or `selectionIndexHolder` is `null`

### SelectionInList2

    public SelectionInList2(ValueModel listHolder)

  Constructs a SelectionInList2 on the given list holder using defaults for the selection holder and selection index holder.

  Parameters:
    `listHolder` - holds the list
  Throws:
    `NullPointerException` - if `listHolder` is `null`

### SelectionInList2

    public SelectionInList2(ValueModel listHolder,
                            ValueModel selectionHolder)

  Constructs a SelectionInList2 on the given list holder, selection holder and selection index holder.

  Parameters:
    `listHolder` - holds the list
    `selectionHolder` - holds the selection
  Throws:
    `NullPointerException` - if `listHolder` or `selectionHolder` is `null`

### SelectionInList2

    public SelectionInList2(ValueModel listHolder,
                            ValueModel selectionHolder,
                            ValueModel selectionIndexHolder)

  Constructs a SelectionInList2 on the given list holder, selection holder and selection index holder.

  Parameters:
    `listHolder` - holds the list
    `selectionHolder` - holds the selection
    `selectionIndexHolder` - holds the selection index
  Throws:
    `NullPointerException` - if `listHolder`, `selectionHolder`, or `selectionIndexHolder` is `null`
    `IllegalArgumentException` - if the listHolder contents is neither a List nor a ListModel

Method Detail

### getSelection

    public Object getSelection()

  Looks up and returns the current selection using the current selection index. Returns `null` if no object is selected or if the list has no elements.

  Returns:
    the current selection, `null` if none is selected

### setSelection

    public void setSelection(Object newSelection)

  Sets the first list element that equals the given new selection as new selection. Does nothing if the list is empty.

  Parameters:
    `newSelection` - the object to be set as new selection

### getSelectionHolder

    public ValueModel getSelectionHolder()

  Returns the selection holder.

  Returns:
    the selection holder

### setSelectionHolder

    public void setSelectionHolder(ValueModel newSelectionHolder)

  Sets a new selection holder. Does nothing if the new is the same as before. The selection remains unchanged and is still driven by the selection index holder. It's just that future index changes will update the new selection holder and that future selection holder changes affect the selection index.

  Parameters:
    `newSelectionHolder` - the selection holder to set
  Throws:
    `NullPointerException` - if the new selection holder is null

### getSelectionIndex

    public int getSelectionIndex()

  Returns the selection index.

  Returns:
    the selection index
  Throws:
    `NullPointerException` - if the selection index holder has a null Object set

### setSelectionIndex

    public void setSelectionIndex(int newSelectionIndex)

  Sets a new selection index. Does nothing if it is the same as before.

  Parameters:
    `newSelectionIndex` - the selection index to be set
  Throws:
    `IndexOutOfBoundsException` - if the new selection index is outside the bounds of the list

### getSelectionIndexHolder

    public ValueModel getSelectionIndexHolder()

  Returns the selection index holder.

  Returns:
    the selection index holder

### setSelectionIndexHolder

    public void setSelectionIndexHolder(ValueModel newSelectionIndexHolder)

  Sets a new selection index holder. Does nothing if the new is the same as before.

  Parameters:
    `newSelectionIndexHolder` - the selection index holder to set
  Throws:
    `NullPointerException` - if the new selection index holder is null
    `IllegalArgumentException` - if the value of the new selection index holder is null

### hasSelection

    public boolean hasSelection()

  Checks and answers if an element is selected.

  Returns:
    true if an element is selected, false otherwise

### isSelectionEmpty

    public boolean isSelectionEmpty()

  Checks and answers whether the selection is empty or not. Unlike #hasSelection, the underlying property #selectionEmpty for this method is bound. I.e. you can observe this property using a PropertyChangeListener to update UI state.

  Returns:
    true if nothing is selected, false if there's a selection
  See Also:
    `clearSelection()`, `hasSelection()`

### clearSelection

    public void clearSelection()

  Clears the selection of this SelectionInList2 - if any.

### fireSelectedContentsChanged

    public void fireSelectedContentsChanged()

  Notifies all registered ListDataListeners that the contents of the selected list item - if any - has changed. Useful to update a presentation after editing the selection. See the tutorial's AlbumManagerModel for an example how to use this feature.

  If the list holder holds a ListModel, this SelectionInList2 listens to ListDataEvents fired by that ListModel, and forwards these events by invoking the associated `#fireXXX` method, which in turn notifies all registered ListDataListeners. Therefore if you fire ListDataEvents in an underlying ListModel, you don't need this method and should not use it to avoid sending duplicate ListDataEvents.

  See Also:
    `ListModel`, `ListDataListener`, `ListDataEvent`

### updateList

    protected void updateList(List oldList,
                              List newList)

  Updates the selection index and fires a property change for the list and a contents change event.

  Overrides:
    `updateList` in class `ListHolder`
  Parameters:
    `oldList` - the old List content
    `newList` - the new List content

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Copyright © 2002-2006 JGoodies Karsten Lentzsch. All Rights Reserved.