gcc/libjava/classpath/javax/swing/DefaultComboBoxModel.java

/* DefaultComboBoxModel.java --
   Copyright (C) 2002, 2004, 2005, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package javax.swing;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Vector;

import javax.swing.event.ListDataEvent;


/**
 * A model that stores a list of elements and a selected item (which may be
 * <code>null</code>).  Changes to the model are signalled to listeners using
 * {@link ListDataEvent}.  This model is designed for use by the
 * {@link JComboBox} component.
 *
 * @author Andrew Selkirk
 * @author Olga Rodimina
 * @author Robert Schuster
 */
public class DefaultComboBoxModel extends AbstractListModel
  implements MutableComboBoxModel, Serializable
{
  private static final long serialVersionUID = 6698657703676921904L;

  /**
   * Storage for the elements in the model's list.
   */
  private Vector list;

  /**
   * The selected item (<code>null</code> indicates no selection).
   */
  private Object selectedItem = null;

  /**
   * Creates a new model, initially empty.
   */
  public DefaultComboBoxModel()
  {
    list = new Vector();
  }

  /**
   * Creates a new model and initializes its item list to the values in the
   * given array.  The selected item is set to the first item in the array, or
   * <code>null</code> if the array length is zero.
   *
   * @param items  an array containing items for the model (<code>null</code>
   *               not permitted).
   *
   * @throws NullPointerException if <code>items</code> is <code>null</code>.
   */
  public DefaultComboBoxModel(Object[] items)
  {
    list = new Vector(Arrays.asList(items));
    if (list.size() > 0)
      selectedItem = list.get(0);
  }

  /**
   * Creates a new model and initializes its item list to the values in the
   * given vector.  The selected item is set to the first item in the vector,
   * or <code>null</code> if the vector length is zero.
   *
   * @param vector  a vector containing items for the model (<code>null</code>
   *                not permitted).
   *
   * @throws NullPointerException if <code>vector</code> is <code>null</code>.
   */
  public DefaultComboBoxModel(Vector<?> vector)
  {
    this.list = vector;
    if (getSize() > 0)
      selectedItem = vector.get(0);
  }

  /**
   * Adds an element to the model's item list and sends a {@link ListDataEvent}
   * to all registered listeners.  If the new element is the first item added
   * to the list, and the selected item is <code>null</code>, the new element
   * is set as the selected item.
   *
   * @param object item to add to the model's item list.
   */
  public void addElement(Object object)
  {
    list.addElement(object);
    int index = list.size() - 1;
    fireIntervalAdded(this, index, index);
    if (list.size() == 1 && selectedItem == null)
      setSelectedItem(object);
  }

  /**
   * Removes the element at the specified index from the model's item list
   * and sends a {@link ListDataEvent} to all registered listeners.  If the
   * element removed was the selected item, then the preceding element becomes
   * the new selected item (or the next element, if there is no preceding
   * element).
   *
   * @param index  the index of the item to remove.
   *
   * @throws ArrayIndexOutOfBoundsException if <code>index</code> is out of
   *         bounds.
   */
  public void removeElementAt(int index)
  {
    int selected = getIndexOf(selectedItem);
    if (selected == index) // choose a new selected item
      {
        if (selected > 0)
          setSelectedItem(getElementAt(selected - 1));
        else
          setSelectedItem(getElementAt(selected + 1));
      }
    list.removeElementAt(index);
    fireIntervalRemoved(this, index, index);
  }

  /**
   * Adds an element at the specified index in the model's item list
   * and sends a {@link ListDataEvent} to all registered listeners.
   *
   * @param object element to insert
   * @param index index specifing position in the list where given element
   *        should be inserted.
   *
   * @throws ArrayIndexOutOfBoundsException if <code>index</code> is out of
   *         bounds.
   *
   * @see #addElement(Object)
   */
  public void insertElementAt(Object object, int index)
  {
    list.insertElementAt(object, index);
    fireIntervalAdded(this, index, index);
  }

  /**
   * Removes an element from the model's item list and sends a
   * {@link ListDataEvent} to all registered listeners.  If the item to be
   * removed is the current selected item, a new selected item will be set.
   * If the element is not found in the model's item list, this method does
   * nothing.
   *
   * @param object  the element to remove.
   */
  public void removeElement(Object object)
  {
    int index = getIndexOf(object);
    if (index != -1)
      removeElementAt(index);
  }

  /**
   * Removes all the items from the model's item list, resets and selected item
   * to <code>null</code>, and sends a {@link ListDataEvent} to all registered
   * listeners.
   */
  public void removeAllElements()
  {
    selectedItem = null;
    int size = getSize();
    if (size > 0)
      {
        list.clear();
        fireIntervalRemoved(this, 0, size - 1);
      }
  }

  /**
   * Returns the number of items in the model's item list.
   *
   * @return The number of items in the model's item list.
   */
  public int getSize()
  {
    return list.size();
  }

  /**
   * Sets the selected item for the model and sends a {@link ListDataEvent} to
   * all registered listeners.  The start and end index of the event is set to
   * -1 to indicate the model's selection has changed, and not its contents.
   *
   * @param object  the new selected item (<code>null</code> permitted).
   */
  public void setSelectedItem(Object object)
  {
    // No item is selected and object is null, so no change required.
    if (selectedItem == null && object == null)
      return;

    // object is already selected so no change required.
    if (selectedItem != null && selectedItem.equals(object))
      return;

    // Simply return if object is not in the list.
    if (object != null && getIndexOf(object) == -1)
      return;

    // Here we know that object is either an item in the list or null.

    // Handle the three change cases: selectedItem is null, object is
    // non-null; selectedItem is non-null, object is null;
    // selectedItem is non-null, object is non-null and they're not
    // equal.
    selectedItem = object;
    fireContentsChanged(this, -1, -1);
  }

  /**
   * Returns the selected item.
   *
   * @return The selected item (possibly <code>null</code>).
   */
  public Object getSelectedItem()
  {
    return selectedItem;
  }

  /**
   * Returns the element at the specified index in the model's item list.
   *
   * @param index  the element index.
   *
   * @return The element at the specified index in the model's item list, or
   *         <code>null</code> if the <code>index</code> is outside the bounds
   *         of the list.
   */
  public Object getElementAt(int index)
  {
    if (index < 0 || index >= list.size())
      return null;
    return list.elementAt(index);
  }

  /**
   * Returns the index of the specified element in the model's item list.
   *
   * @param object  the element.
   *
   * @return The index of the specified element in the model's item list.
   */
  public int getIndexOf(Object object)
  {
    return list.indexOf(object);
  }
}