ListSelectionModel.java

/* ListSelectionModel.java -- 
   Copyright (C) 2002, 2006, Free Software Foundation, Inc.

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package javax.swing;

import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

/**
 * A model that tracks the selection status of a list of items.  Each item in 
 * the list is identified by a zero-based index only, so the model can be used
 * to track the selection status of any type of list.  The model 
 * supports three modes:
 * <ul>
 * <li><code>SINGLE_SELECTION</code> - only one item in the list may be 
 *     selected;</li>
 * <li><code>SINGLE_INTERVAL_SELECTION</code> - only one interval in the list 
 *     may be selected;</li>
 * <li><code>MULTIPLE_INTERVAL_SELECTION</code> - any combination of items in 
 *     the list may be selected.</li>
 * </ul>
 * The model uses an event notification mechanism to notify listeners (see 
 * {@link ListSelectionListener}) about updates to the selection model.
 * <p>
 * This model is used to track row selections in the {@link JList} component,
 * and row and column selections in the {@link JTable} component.
 */
public interface ListSelectionModel
{
  
  /**
   * A selection mode in which only one item can be selected.
   * 
   * @see #setSelectionMode(int)
   */
  int SINGLE_SELECTION = 0;

  /**
   * A selection mode in which a single interval can be selected (an interval
   * is a range containing one or more contiguous items).
   * 
   * @see #setSelectionMode(int)
   */
  int SINGLE_INTERVAL_SELECTION = 1;

  /**
   * A selection mode in which any combination of items can be selected.
   * 
   * @see #setSelectionMode(int)
   */
  int MULTIPLE_INTERVAL_SELECTION = 2;

  /**
   * Sets the selection mode.
   * <p>
   * FIXME: The spec is silent about what happens to existing selections, for
   * example when changing from an interval selection to single selection.
   * 
   * @param mode  one of {@link #SINGLE_SELECTION}, 
   *     {@link #SINGLE_INTERVAL_SELECTION} and 
   *     {@link #MULTIPLE_INTERVAL_SELECTION}.
   *     
   * @see #getSelectionMode()
   * 
   * @throws IllegalArgumentException if <code>mode</code> is not one of the
   *     specified values.
   */
  void setSelectionMode(int mode);

  /**
   * Returns the selection mode, which is one of {@link #SINGLE_SELECTION}, 
   * {@link #SINGLE_INTERVAL_SELECTION} and 
   * {@link #MULTIPLE_INTERVAL_SELECTION}.
   * 
   * @return The selection mode.
   * 
   * @see #setSelectionMode(int)
   */
  int getSelectionMode();

  /**
   * Clears the current selection from the model.  If the selection state 
   * changes (that is, the existing selection is non-empty) a 
   * {@link ListSelectionEvent} should be sent to all registered listeners.
   * <p>
   * FIXME: what happens to the anchor and lead selection indices (the spec
   * is silent about this)?  See:
   * <p>
   * http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4334792
   */
  void clearSelection();

  /**
   * Returns the lowest selected index, or <code>-1</code> if there is no 
   * selection.
   * 
   * @return The lowest selected index.
   * 
   * @see #getMaxSelectionIndex()
   */
  int getMinSelectionIndex();

  /**
   * Returns the highest selected index, or <code>-1</code> if there is no
   * selection.
   * 
   * @return The highest selected index.
   * 
   * @see #getMinSelectionIndex()
   */
  int getMaxSelectionIndex();

  /**
   * Returns <code>true</code> if the specified item is selected, and 
   * <code>false</code> otherwise.  Special note: if <code>index</code> is 
   * negative, this method should return <code>false</code> (no exception 
   * should be thrown).
   * 
   * @param index  the item index (zero-based).
   * 
   * @return <code>true</code> if the specified item is selected, and 
   *     <code>false</code> otherwise.
   */
  boolean isSelectedIndex(int index);

  /**
   * Returns <code>true</code> if there is no selection, and <code>false</code>
   * otherwise.
   * 
   * @return  <code>true</code> if there is no selection, and 
   *     <code>false</code> otherwise.
   */
  boolean isSelectionEmpty();

  /**
   * Sets the selection interval to the specified range (note that 
   * <code>anchor</code> can be less than, equal to, or greater than 
   * <code>lead</code>).  If this results in the selection being changed, 
   * a {@link ListSelectionEvent} is sent to all registered listeners.
   * <p>
   * If the selection mode is {@link #SINGLE_SELECTION}, only the 
   * <code>lead</code> item is selected.
   * 
   * @param anchor  the anchor index.
   * @param lead  the lead index.
   */
  void setSelectionInterval(int anchor, int lead);

  /**
   * Marks the items in the specified interval as selected.  The behaviour of 
   * this method depends on the selection mode:
   * <ul>
   * <li><code>SINGLE_SELECTION</code> - only the <code>lead</code> item is 
   *     selected;</li>
   * <li><code>SINGLE_INTERVAL_SELECTION</code> - the existing selection 
   *     interval is replaced by the specified interval;</li>
   * <li><code>MULTIPLE_INTERVAL_SELECTION</code> - the specified interval is 
   *     merged into the currently selected intervals.</li>
   * </ul>
   * Note that <code>anchor</code> can be less than, equal to, or greater than 
   * <code>lead</code>.
   * 
   * @param anchor  the index of the anchor item
   * @param lead  the index of the lead item.
   */
  void addSelectionInterval(int anchor, int lead);

  /**
   * Marks the items in the specified interval as not selected.  The behaviour 
   * of this method depends on the selection mode:
   * <ul>
   * <li><code>SINGLE_SELECTION</code> - XXX;</li>
   * <li><code>SINGLE_INTERVAL_SELECTION</code> - XXX;</li>
   * <li><code>MULTIPLE_INTERVAL_SELECTION</code> - XXX.</li>
   * </ul>
   * Note that <code>anchor</code> can be less than, equal to, or greater than 
   * <code>lead</code>.
   * 
   * @param anchor  the index of the anchor item
   * @param lead  the index of the lead item.
   */
  void removeSelectionInterval(int anchor, int lead);

  /**
   * Inserts a new interval containing <code>length</code> items at the
   * specified <code>index</code> (the <code>before</code> flag indicates
   * whether the range is inserted before or after the existing item at
   * <code>index</code>).
   * 
   * FIXME: What is the selection status of the new items? Bug 4870694.
   * FIXME: What event is generated?
   * 
   * @param index  the index of the item. 
   * @param length  the number of items in the interval to be inserted.
   * @param before  if <code>true</code>, the interval should be inserted 
   *     before <code>index</code>, otherwise it is inserted after.
   *     
   * @see #removeIndexInterval(int, int)
   */
  void insertIndexInterval(int index, int length, boolean before);

  /**
   * Removes the items in the specified range (inclusive) from the selection
   * model.  This method should be called when an interval is deleted from 
   * the underlying list.
   * 
   * FIXME: what happens to the lead and anchor indices if they are part of 
   * the range that is removed? 
   * FIXME: what event is generated
   * 
   * @param index0  XXX
   * @param index1  XXX
   * 
   * @see #insertIndexInterval(int, int, boolean)
   */
  void removeIndexInterval(int index0, int index1);

  /**
   * Returns the index of the anchor item. 
   * 
   * @return The index of the anchor item.
   * 
   * @see #setAnchorSelectionIndex(int)
   */
  int getAnchorSelectionIndex();

  /**
   * Sets the index of the anchor item.
   * 
   * @param index  the item index.
   * 
   * @see #getAnchorSelectionIndex()
   */
  void setAnchorSelectionIndex(int index);

  /**
   * Returns the index of the lead item.
   * 
   * @return The index of the lead item.
   * 
   * @see #setLeadSelectionIndex(int)
   */
  int getLeadSelectionIndex();

  /**
   * Sets the index of the lead item.
   * 
   * @param index  the item index.
   * 
   * @see #getLeadSelectionIndex()
   */
  void setLeadSelectionIndex(int index);

  /**
   * Sets the flag that is passed to listeners for each change notification.
   * If a sequence of changes is made to the selection model, this flag should
   * be set to <code>true</code> at the start of the sequence, and 
   * <code>false</code> for the last change - this gives listeners the option
   * to ignore interim changes if that is more efficient.
   * 
   * @param valueIsAdjusting  the flag value.
   * 
   * @see #getValueIsAdjusting()
   */
  void setValueIsAdjusting(boolean valueIsAdjusting);

  /**
   * Returns a flag that is passed to registered listeners when changes are
   * made to the model.  See the description for 
   * {@link #setValueIsAdjusting(boolean)} for more information.
   *  
   * @return The flag.
   */
  boolean getValueIsAdjusting();

  /**
   * Registers a listener with the model so that it receives notification
   * of changes to the model.
   * 
   * @param listener  the listener (<code>null</code> ignored).
   * 
   * @see #removeListSelectionListener(ListSelectionListener)
   */
  void addListSelectionListener(ListSelectionListener listener);

  /**
   * Deregisters a listener so that it no longer receives notification of
   * changes to the model.  If the specified listener is not registered with
   * the model, or is <code>null</code>, this method does nothing.
   * 
   * @param listener  the listener (<code>null</code> ignored).
   * 
   * @see #addListSelectionListener(ListSelectionListener)
   */
  void removeListSelectionListener(ListSelectionListener listener);

}