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package javax.swing;

import java.util.*;

import java.io.Serializable;

The default model for combo boxes.
Author:
Arnaud Weber, Tom Santos
Type parameters:
<E> – the type of the elements of this model/**
 * The default model for combo boxes.
 *
 * @param <E> the type of the elements of this model
 *
 * @author Arnaud Weber
 * @author Tom Santos
 */

public class DefaultComboBoxModel<E> extends AbstractListModel<E> implements MutableComboBoxModel<E>, Serializable {
    Vector<E> objects;
    Object selectedObject;

    
Constructs an empty DefaultComboBoxModel object.
/**
     * Constructs an empty DefaultComboBoxModel object.
     */
    public DefaultComboBoxModel() {
        objects = new Vector<E>();
    }

    
Constructs a DefaultComboBoxModel object initialized with
an array of objects.
Params:
items –  an array of Object objects/**
     * Constructs a DefaultComboBoxModel object initialized with
     * an array of objects.
     *
     * @param items  an array of Object objects
     */
    public DefaultComboBoxModel(final E items[]) {
        objects = new Vector<E>(items.length);

        int i,c;
        for ( i=0,c=items.length;i<c;i++ )
            objects.addElement(items[i]);

        if ( getSize() > 0 ) {
            selectedObject = getElementAt( 0 );
        }
    }

    
Constructs a DefaultComboBoxModel object initialized with
a vector.
Params:
v –  a Vector object .../**
     * Constructs a DefaultComboBoxModel object initialized with
     * a vector.
     *
     * @param v  a Vector object ...
     */
    public DefaultComboBoxModel(Vector<E> v) {
        objects = v;

        if ( getSize() > 0 ) {
            selectedObject = getElementAt( 0 );
        }
    }

    // implements javax.swing.ComboBoxModel
    
Set the value of the selected item. The selected item may be null.
Params:
anObject – The combo box value or null for no selection./**
     * Set the value of the selected item. The selected item may be null.
     *
     * @param anObject The combo box value or null for no selection.
     */
    public void setSelectedItem(Object anObject) {
        if ((selectedObject != null && !selectedObject.equals( anObject )) ||
            selectedObject == null && anObject != null) {
            selectedObject = anObject;
            fireContentsChanged(this, -1, -1);
        }
    }

    // implements javax.swing.ComboBoxModel
    public Object getSelectedItem() {
        return selectedObject;
    }

    // implements javax.swing.ListModel
    public int getSize() {
        return objects.size();
    }

    // implements javax.swing.ListModel
    public E getElementAt(int index) {
        if ( index >= 0 && index < objects.size() )
            return objects.elementAt(index);
        else
            return null;
    }

    
Returns the index-position of the specified object in the list.
Params:
anObject – 
Returns:
an int representing the index position, where 0 is
        the first position/**
     * Returns the index-position of the specified object in the list.
     *
     * @param anObject
     * @return an int representing the index position, where 0 is
     *         the first position
     */
    public int getIndexOf(Object anObject) {
        return objects.indexOf(anObject);
    }

    // implements javax.swing.MutableComboBoxModel
    public void addElement(E anObject) {
        objects.addElement(anObject);
        fireIntervalAdded(this,objects.size()-1, objects.size()-1);
        if ( objects.size() == 1 && selectedObject == null && anObject != null ) {
            setSelectedItem( anObject );
        }
    }

    // implements javax.swing.MutableComboBoxModel
    public void insertElementAt(E anObject,int index) {
        objects.insertElementAt(anObject,index);
        fireIntervalAdded(this, index, index);
    }

    // implements javax.swing.MutableComboBoxModel
    public void removeElementAt(int index) {
        if ( getElementAt( index ) == selectedObject ) {
            if ( index == 0 ) {
                setSelectedItem( getSize() == 1 ? null : getElementAt( index + 1 ) );
            }
            else {
                setSelectedItem( getElementAt( index - 1 ) );
            }
        }

        objects.removeElementAt(index);

        fireIntervalRemoved(this, index, index);
    }

    // implements javax.swing.MutableComboBoxModel
    public void removeElement(Object anObject) {
        int index = objects.indexOf(anObject);
        if ( index != -1 ) {
            removeElementAt(index);
        }
    }

    
Empties the list.
/**
     * Empties the list.
     */
    public void removeAllElements() {
        if ( objects.size() > 0 ) {
            int firstIndex = 0;
            int lastIndex = objects.size() - 1;
            objects.removeAllElements();
            selectedObject = null;
            fireIntervalRemoved(this, firstIndex, lastIndex);
        } else {
            selectedObject = null;
        }
    }
}