# Class DefaultListSelectionModel

java.lang.Object
javax.swing.DefaultListSelectionModel

All Implemented Interfaces:
  `Serializable, Cloneable, ListSelectionModel`

public class DefaultListSelectionModel extends Object implements ListSelectionModel, Cloneable, Serializable
Default data model for list selections.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans has been added to the `java.beans` package. Please see `XMLEncoder`.

Since:
  1.2
See Also:
  - `ListSelectionModel`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected boolean`
  `leadAnchorNotificationEnabled`
  Whether or not the lead anchor notification is enabled.
  `protected EventListenerList`
  `listenerList`
  The list of listeners.

  ### Fields declared in interface ListSelectionModel

  `MULTIPLE_INTERVAL_SELECTION, SINGLE_INTERVAL_SELECTION, SINGLE_SELECTION`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DefaultListSelectionModel()`
  Constructs a `DefaultListSelectionModel`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `addListSelectionListener(ListSelectionListener l)`
  Add a listener to the list that's notified each time a change to the selection occurs.
  `void`
  `addSelectionInterval(int index0, int index1)`
  Changes the selection to be the set union of the current selection and the indices between `index0` and `index1` inclusive.
  `void`
  `clearSelection()`
  Change the selection to the empty set.
  `Object`
  `clone()`
  Returns a clone of this selection model with the same selection.
  `protected void`
  `fireValueChanged(boolean isAdjusting)`
  Notifies listeners that we have ended a series of adjustments.
  `protected void`
  `fireValueChanged(int firstIndex, int lastIndex)`
  Notifies `ListSelectionListeners` that the value of the selection, in the closed interval `firstIndex`, `lastIndex`, has changed.
  `protected void`
  `fireValueChanged(int firstIndex, int lastIndex, boolean isAdjusting)`
  Notifies `ListSelectionListeners` that the value of the selection, in the closed interval `firstIndex`, `lastIndex`, has changed and if this is the final change in the series of adjustments.
  `int`
  `getAnchorSelectionIndex()`
  Return the first index argument from the most recent call to setSelectionInterval(), addSelectionInterval() or removeSelectionInterval().
  `int`
  `getLeadSelectionIndex()`
  Return the second index argument from the most recent call to setSelectionInterval(), addSelectionInterval() or removeSelectionInterval().
  `<T extends EventListener>
  T[]`
  `getListeners(Class<T> listenerType)`
  Returns an array of all the objects currently registered as `FooListener`s upon this model.
  `ListSelectionListener[]`
  `getListSelectionListeners()`
  Returns an array of all the list selection listeners registered on this `DefaultListSelectionModel`.
  `int`
  `getMaxSelectionIndex()`
  Returns the last selected index or -1 if the selection is empty.
  `int`
  `getMinSelectionIndex()`
  Returns the first selected index or -1 if the selection is empty.
  `int`
  `getSelectionMode()`
  Returns the current selection mode.
  `boolean`
  `getValueIsAdjusting()`
  Returns `true` if the selection is undergoing a series of changes.
  `void`
  `insertIndexInterval(int index, int length, boolean before)`
  Insert length indices beginning before/after index.
  `boolean`
  `isLeadAnchorNotificationEnabled()`
  Returns the value of the `leadAnchorNotificationEnabled` flag.
  `boolean`
  `isSelectedIndex(int index)`
  Returns true if the specified index is selected.
  `boolean`
  `isSelectionEmpty()`
  Returns true if no indices are selected.
  `void`
  `moveLeadSelectionIndex(int leadIndex)`
  Set the lead selection index, leaving all selection values unchanged.
  `void`
  `removeIndexInterval(int index0, int index1)`
  Remove the indices in the interval index0,index1 (inclusive) from the selection model.
  `void`
  `removeListSelectionListener(ListSelectionListener l)`
  Remove a listener from the list that's notified each time a change to the selection occurs.
  `void`
  `removeSelectionInterval(int index0, int index1)`
  Changes the selection to be the set difference of the current selection and the indices between `index0` and `index1` inclusive.
  `void`
  `setAnchorSelectionIndex(int anchorIndex)`
  Set the anchor selection index, leaving all selection values unchanged.
  `void`
  `setLeadAnchorNotificationEnabled(boolean flag)`
  Sets the value of the leadAnchorNotificationEnabled flag.
  `void`
  `setLeadSelectionIndex(int leadIndex)`
  Sets the lead selection index, ensuring that values between the anchor and the new lead are either all selected or all deselected.
  `void`
  `setSelectionInterval(int index0, int index1)`
  Changes the selection to be between `index0` and `index1` inclusive.
  `void`
  `setSelectionMode(int selectionMode)`
  Sets the selection mode.
  `void`
  `setValueIsAdjusting(boolean isAdjusting)`
  Sets the `valueIsAdjusting` property, which indicates whether or not upcoming selection changes should be considered part of a single change.
  `String`
  `toString()`
  Returns a string that displays and identifies this object's properties.

  ### Methods declared in class Object

  `equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

  ### Methods declared in interface ListSelectionModel

  `getSelectedIndices, getSelectedItemsCount`

- ## Field Details

  - ### listenerList

    protected EventListenerList listenerList
    The list of listeners.

  - ### leadAnchorNotificationEnabled

    protected boolean leadAnchorNotificationEnabled
    Whether or not the lead anchor notification is enabled.

- ## Constructor Details

  - ### DefaultListSelectionModel

    public DefaultListSelectionModel()
    Constructs a `DefaultListSelectionModel`.

- ## Method Details

  - ### getMinSelectionIndex

    public int getMinSelectionIndex()
    Returns the first selected index or -1 if the selection is empty.
    Specified by:
      `getMinSelectionIndex` in interface `ListSelectionModel`
    Returns:
      the first selected index or -1 if the selection is empty.

  - ### getMaxSelectionIndex

    public int getMaxSelectionIndex()
    Returns the last selected index or -1 if the selection is empty.
    Specified by:
      `getMaxSelectionIndex` in interface `ListSelectionModel`
    Returns:
      the last selected index or -1 if the selection is empty.

  - ### getValueIsAdjusting

    public boolean getValueIsAdjusting()
    Returns `true` if the selection is undergoing a series of changes.
    Specified by:
      `getValueIsAdjusting` in interface `ListSelectionModel`
    Returns:
      true if the selection is undergoing a series of changes
    See Also:
      - `ListSelectionModel.setValueIsAdjusting(boolean)`

  - ### getSelectionMode

    public int getSelectionMode()
    Returns the current selection mode.
    Specified by:
      `getSelectionMode` in interface `ListSelectionModel`
    Returns:
      the current selection mode
    See Also:
      - `ListSelectionModel.setSelectionMode(int)`

  - ### setSelectionMode

    public void setSelectionMode(int selectionMode)
    Sets the selection mode. The following list describes the accepted selection modes:
    - `ListSelectionModel.SINGLE_SELECTION` - Only one list index can be selected at a time. In this mode, `setSelectionInterval` and `addSelectionInterval` are equivalent, both replacing the current selection with the index represented by the second argument (the "lead").
    - `ListSelectionModel.SINGLE_INTERVAL_SELECTION` - Only one contiguous interval can be selected at a time. In this mode, `addSelectionInterval` behaves like `setSelectionInterval` (replacing the current selection), unless the given interval is immediately adjacent to or overlaps the existing selection, and can therefore be used to grow it.
    - `ListSelectionModel.MULTIPLE_INTERVAL_SELECTION` - In this mode, there's no restriction on what can be selected.
    Specified by:
      `setSelectionMode` in interface `ListSelectionModel`
    Parameters:
      `selectionMode` - the selection mode
    Throws:
      `IllegalArgumentException` - if the selection mode isn't one of those allowed
    See Also:
      - `ListSelectionModel.getSelectionMode()`

  - ### isSelectedIndex

    public boolean isSelectedIndex(int index)
    Returns true if the specified index is selected.
    Specified by:
      `isSelectedIndex` in interface `ListSelectionModel`
    Parameters:
      `index` - an index
    Returns:
      `true` if the specified index is selected

  - ### isSelectionEmpty

    public boolean isSelectionEmpty()
    Returns true if no indices are selected.
    Specified by:
      `isSelectionEmpty` in interface `ListSelectionModel`
    Returns:
      `true` if no indices are selected.

  - ### addListSelectionListener

    public void addListSelectionListener(ListSelectionListener l)
    Add a listener to the list that's notified each time a change to the selection occurs.
    Specified by:
      `addListSelectionListener` in interface `ListSelectionModel`
    Parameters:
      `l` - the ListSelectionListener
    See Also:
      - `ListSelectionModel.removeListSelectionListener(ListSelectionListener)`
      - `ListSelectionModel.setSelectionInterval(int, int)`
      - `ListSelectionModel.addSelectionInterval(int, int)`
      - `ListSelectionModel.removeSelectionInterval(int, int)`
      - `ListSelectionModel.clearSelection()`
      - `ListSelectionModel.insertIndexInterval(int, int, boolean)`
      - `ListSelectionModel.removeIndexInterval(int, int)`

  - ### removeListSelectionListener

    public void removeListSelectionListener(ListSelectionListener l)
    Remove a listener from the list that's notified each time a change to the selection occurs.
    Specified by:
      `removeListSelectionListener` in interface `ListSelectionModel`
    Parameters:
      `l` - the ListSelectionListener
    See Also:
      - `ListSelectionModel.addListSelectionListener(ListSelectionListener)`

  - ### getListSelectionListeners

    public ListSelectionListener[] getListSelectionListeners()
    Returns an array of all the list selection listeners registered on this `DefaultListSelectionModel`.
    Returns:
      all of this model's `ListSelectionListener`s or an empty array if no list selection listeners are currently registered
    Since:
      1.4
    See Also:
      - `addListSelectionListener(ListSelectionListener)`
      - `removeListSelectionListener(ListSelectionListener)`

  - ### fireValueChanged

    protected void fireValueChanged(boolean isAdjusting)
    Notifies listeners that we have ended a series of adjustments.
    Parameters:
      `isAdjusting` - true if this is the final change in a series of adjustments

  - ### fireValueChanged

    protected void fireValueChanged(int firstIndex, int lastIndex)
    Notifies `ListSelectionListeners` that the value of the selection, in the closed interval `firstIndex`, `lastIndex`, has changed.
    Parameters:
      `firstIndex` - the first index in the interval
      `lastIndex` - the last index in the interval

  - ### fireValueChanged

    protected void fireValueChanged(int firstIndex, int lastIndex, boolean isAdjusting)
    Notifies `ListSelectionListeners` that the value of the selection, in the closed interval `firstIndex`, `lastIndex`, has changed and if this is the final change in the series of adjustments.
    Parameters:
      `firstIndex` - the first index in the interval
      `lastIndex` - the last index in the interval
      `isAdjusting` - true if this is the final change in a series of adjustments
    See Also:
      - `EventListenerList`

  - ### getListeners

    public <T extends EventListener> T[] getListeners(Class<T> listenerType)
    Returns an array of all the objects currently registered as `FooListener`s upon this model. `FooListener`s are registered using the `addFooListener` method.

    You can specify the `listenerType` argument with a class literal, such as `FooListener.class`. For example, you can query a `DefaultListSelectionModel` instance `m` for its list selection listeners with the following code:

        ListSelectionListener[] lsls = (ListSelectionListener[])(m.getListeners(ListSelectionListener.class));

    If no such listeners exist, this method returns an empty array.
    Type Parameters:
      `T` - the type of `EventListener` class being requested
    Parameters:
      `listenerType` - the type of listeners requested; this parameter should specify an interface that descends from `java.util.EventListener`
    Returns:
      an array of all objects registered as `FooListener`s on this model, or an empty array if no such listeners have been added
    Throws:
      `ClassCastException` - if `listenerType` doesn't specify a class or interface that implements `java.util.EventListener`
    Since:
      1.3
    See Also:
      - `getListSelectionListeners()`

  - ### setLeadAnchorNotificationEnabled

    public void setLeadAnchorNotificationEnabled(boolean flag)
    Sets the value of the leadAnchorNotificationEnabled flag.
    Parameters:
      `flag` - boolean value for `leadAnchorNotificationEnabled`
    See Also:
      - `isLeadAnchorNotificationEnabled()`

  - ### isLeadAnchorNotificationEnabled

    public boolean isLeadAnchorNotificationEnabled()
    Returns the value of the `leadAnchorNotificationEnabled` flag. When `leadAnchorNotificationEnabled` is true the model generates notification events with bounds that cover all the changes to the selection plus the changes to the lead and anchor indices. Setting the flag to false causes a narrowing of the event's bounds to include only the elements that have been selected or deselected since the last change. Either way, the model continues to maintain the lead and anchor variables internally. The default is true.

    Note: It is possible for the lead or anchor to be changed without a change to the selection. Notification of these changes is often important, such as when the new lead or anchor needs to be updated in the view. Therefore, caution is urged when changing the default value.

    Returns:
      the value of the `leadAnchorNotificationEnabled` flag
    See Also:
      - `setLeadAnchorNotificationEnabled(boolean)`

  - ### clearSelection

    public void clearSelection()
    Change the selection to the empty set. If this represents a change to the current selection then notify each ListSelectionListener.
    Specified by:
      `clearSelection` in interface `ListSelectionModel`
    See Also:
      - `ListSelectionModel.addListSelectionListener(ListSelectionListener)`

  - ### setSelectionInterval

    public void setSelectionInterval(int index0, int index1)
    Changes the selection to be between `index0` and `index1` inclusive. `index0` doesn't have to be less than or equal to `index1`.

    In `SINGLE_SELECTION` selection mode, only the second index is used.

    If this represents a change to the current selection, then each `ListSelectionListener` is notified of the change.

    If either index is `-1`, this method does nothing and returns without exception. Otherwise, if either index is less than `-1`, an `IndexOutOfBoundsException` is thrown.

    Specified by:
      `setSelectionInterval` in interface `ListSelectionModel`
    Parameters:
      `index0` - one end of the interval.
      `index1` - other end of the interval
    Throws:
      `IndexOutOfBoundsException` - if either index is less than `-1` (and neither index is `-1`)
    See Also:
      - `addListSelectionListener(ListSelectionListener)`

  - ### addSelectionInterval

    public void addSelectionInterval(int index0, int index1)
    Changes the selection to be the set union of the current selection and the indices between `index0` and `index1` inclusive.

    In `SINGLE_SELECTION` selection mode, this is equivalent to calling `setSelectionInterval`, and only the second index is used. In `SINGLE_INTERVAL_SELECTION` selection mode, this method behaves like `setSelectionInterval`, unless the given interval is immediately adjacent to or overlaps the existing selection, and can therefore be used to grow it.

    If this represents a change to the current selection, then each `ListSelectionListener` is notified of the change. Note that `index0` doesn't have to be less than or equal to `index1`.

    If either index is `-1`, this method does nothing and returns without exception. Otherwise, if either index is less than `-1`, an `IndexOutOfBoundsException` is thrown.

    Specified by:
      `addSelectionInterval` in interface `ListSelectionModel`
    Parameters:
      `index0` - one end of the interval.
      `index1` - other end of the interval
    Throws:
      `IndexOutOfBoundsException` - if either index is less than `-1` (and neither index is `-1`)
    See Also:
      - `addListSelectionListener(ListSelectionListener)`
      - `setSelectionInterval(int, int)`

  - ### removeSelectionInterval

    public void removeSelectionInterval(int index0, int index1)
    Changes the selection to be the set difference of the current selection and the indices between `index0` and `index1` inclusive. `index0` doesn't have to be less than or equal to `index1`.

    In `SINGLE_INTERVAL_SELECTION` selection mode, if the removal would produce two disjoint selections, the removal is extended through the greater end of the selection. For example, if the selection is `0-10` and you supply indices `5,6` (in any order) the resulting selection is `0-4`.

    If this represents a change to the current selection, then each `ListSelectionListener` is notified of the change.

    If either index is `-1`, this method does nothing and returns without exception. Otherwise, if either index is less than `-1`, an `IndexOutOfBoundsException` is thrown.

    Specified by:
      `removeSelectionInterval` in interface `ListSelectionModel`
    Parameters:
      `index0` - one end of the interval
      `index1` - other end of the interval
    Throws:
      `IndexOutOfBoundsException` - if either index is less than `-1` (and neither index is `-1`)
    See Also:
      - `addListSelectionListener(ListSelectionListener)`

  - ### insertIndexInterval

    public void insertIndexInterval(int index, int length, boolean before)
    Insert length indices beginning before/after index. If the value at index is itself selected and the selection mode is not SINGLE_SELECTION, set all of the newly inserted items as selected. Otherwise leave them unselected. This method is typically called to sync the selection model with a corresponding change in the data model.
    Specified by:
      `insertIndexInterval` in interface `ListSelectionModel`
    Parameters:
      `index` - the beginning of the interval
      `length` - the length of the interval
      `before` - if `true`, interval inserts before the `index`, otherwise, interval inserts after the `index`
    Throws:
      `IndexOutOfBoundsException` - if either `index` or `length` is negative

  - ### removeIndexInterval

    public void removeIndexInterval(int index0, int index1)
    Remove the indices in the interval index0,index1 (inclusive) from the selection model. This is typically called to sync the selection model width a corresponding change in the data model. Note that (as always) index0 need not be <= index1.
    Specified by:
      `removeIndexInterval` in interface `ListSelectionModel`
    Parameters:
      `index0` - the beginning of the interval
      `index1` - the end of the interval
    Throws:
      `IndexOutOfBoundsException` - if either index is negative

  - ### setValueIsAdjusting

    public void setValueIsAdjusting(boolean isAdjusting)
    Sets the `valueIsAdjusting` property, which indicates whether or not upcoming selection changes should be considered part of a single change. The value of this property is used to initialize the `valueIsAdjusting` property of the `ListSelectionEvent`s that are generated.

    For example, if the selection is being updated in response to a user drag, this property can be set to `true` when the drag is initiated and set to `false` when the drag is finished. During the drag, listeners receive events with a `valueIsAdjusting` property set to `true`. At the end of the drag, when the change is finalized, listeners receive an event with the value set to `false`. Listeners can use this pattern if they wish to update only when a change has been finalized.

    Setting this property to `true` begins a series of changes that is to be considered part of a single change. When the property is changed back to `false`, an event is sent out characterizing the entire selection change (if there was one), with the event's `valueIsAdjusting` property set to `false`.

    Specified by:
      `setValueIsAdjusting` in interface `ListSelectionModel`
    Parameters:
      `isAdjusting` - the new value of the property
    See Also:
      - `ListSelectionModel.getValueIsAdjusting()`
      - `ListSelectionEvent.getValueIsAdjusting()`

  - ### toString

    public String toString()
    Returns a string that displays and identifies this object's properties.
    Overrides:
      `toString` in class `Object`
    Returns:
      a `String` representation of this object

  - ### clone

    public Object clone() throws CloneNotSupportedException
    Returns a clone of this selection model with the same selection. `listenerLists` are not duplicated.
    Overrides:
      `clone` in class `Object`
    Returns:
      a clone of this instance.
    Throws:
      `CloneNotSupportedException` - if the selection model does not both (a) implement the Cloneable interface and (b) define a `clone` method.
    See Also:
      - `Cloneable`

  - ### getAnchorSelectionIndex

    public int getAnchorSelectionIndex()
    Return the first index argument from the most recent call to setSelectionInterval(), addSelectionInterval() or removeSelectionInterval(). The most recent index0 is considered the "anchor" and the most recent index1 is considered the "lead". Some interfaces display these indices specially, e.g. Windows95 displays the lead index with a dotted yellow outline.
    Specified by:
      `getAnchorSelectionIndex` in interface `ListSelectionModel`
    Returns:
      the anchor selection index
    See Also:
      - `ListSelectionModel.getLeadSelectionIndex()`
      - `ListSelectionModel.setSelectionInterval(int, int)`
      - `ListSelectionModel.addSelectionInterval(int, int)`

  - ### getLeadSelectionIndex

    public int getLeadSelectionIndex()
    Return the second index argument from the most recent call to setSelectionInterval(), addSelectionInterval() or removeSelectionInterval().
    Specified by:
      `getLeadSelectionIndex` in interface `ListSelectionModel`
    Returns:
      the lead selection index.
    See Also:
      - `ListSelectionModel.getAnchorSelectionIndex()`
      - `ListSelectionModel.setSelectionInterval(int, int)`
      - `ListSelectionModel.addSelectionInterval(int, int)`

  - ### setAnchorSelectionIndex

    public void setAnchorSelectionIndex(int anchorIndex)
    Set the anchor selection index, leaving all selection values unchanged. If leadAnchorNotificationEnabled is true, send a notification covering the old and new anchor cells.
    Specified by:
      `setAnchorSelectionIndex` in interface `ListSelectionModel`
    Parameters:
      `anchorIndex` - the anchor selection index
    See Also:
      - `getAnchorSelectionIndex()`
      - `setLeadSelectionIndex(int)`

  - ### moveLeadSelectionIndex

    public void moveLeadSelectionIndex(int leadIndex)
    Set the lead selection index, leaving all selection values unchanged. If leadAnchorNotificationEnabled is true, send a notification covering the old and new lead cells.
    Parameters:
      `leadIndex` - the new lead selection index
    Since:
      1.5
    See Also:
      - `setAnchorSelectionIndex(int)`
      - `setLeadSelectionIndex(int)`
      - `getLeadSelectionIndex()`

  - ### setLeadSelectionIndex

    public void setLeadSelectionIndex(int leadIndex)
    Sets the lead selection index, ensuring that values between the anchor and the new lead are either all selected or all deselected. If the value at the anchor index is selected, first clear all the values in the range [anchor, oldLeadIndex], then select all the values in the range [anchor, newLeadIndex], where oldLeadIndex is the old leadIndex and newLeadIndex is the new one.

    If the value at the anchor index is not selected, do the same thing in reverse selecting values in the old range and deselecting values in the new one.

    Generate a single event for this change and notify all listeners. For the purposes of generating minimal bounds in this event, do the operation in a single pass; that way the first and last index inside the ListSelectionEvent that is broadcast will refer to cells that actually changed value because of this method. If, instead, this operation were done in two steps the effect on the selection state would be the same but two events would be generated and the bounds around the changed values would be wider, including cells that had been first cleared only to later be set.

    This method can be used in the `mouseDragged` method of a UI class to extend a selection.

    Specified by:
      `setLeadSelectionIndex` in interface `ListSelectionModel`
    Parameters:
      `leadIndex` - the lead selection index
    See Also:
      - `getLeadSelectionIndex()`
      - `setAnchorSelectionIndex(int)`