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package java.awt.event;

import java.awt.AWTEvent;
import java.awt.ItemSelectable;


A semantic event which indicates that an item was selected or deselected. This high-level event is generated by an ItemSelectable object (such as a List) when an item is selected or deselected by the user. The event is passed to every ItemListener object which registered to receive such events using the component's addItemListener method. 
 The object that implements the ItemListener interface gets this ItemEvent when the event occurs. The listener is spared the details of processing individual mouse movements and mouse clicks, and can instead process a "meaningful" (semantic) event like "item selected" or "item deselected". 
 An unspecified behavior will be caused if the id parameter of any particular ItemEvent instance is not in the range from ITEM_FIRST to ITEM_LAST. 
 The stateChange of any ItemEvent instance takes one of the following values: 
    
                    
  •  ItemEvent.SELECTED 
  •  ItemEvent.DESELECTED 

Assigning the value different from listed above will cause an unspecified behavior.

Author:Carl Quinn
See Also:
Since:1.1
/**
 * A semantic event which indicates that an item was selected or deselected.
 * This high-level event is generated by an ItemSelectable object (such as a
 * List) when an item is selected or deselected by the user.
 * The event is passed to every {@code ItemListener} object which
 * registered to receive such events using the component's
 * {@code addItemListener} method.
 * <P>
 * The object that implements the {@code ItemListener} interface gets
 * this {@code ItemEvent} when the event occurs. The listener is
 * spared the details of processing individual mouse movements and mouse
 * clicks, and can instead process a "meaningful" (semantic) event like
 * "item selected" or "item deselected".
 * <p>
 * An unspecified behavior will be caused if the {@code id} parameter
 * of any particular {@code ItemEvent} instance is not
 * in the range from {@code ITEM_FIRST} to {@code ITEM_LAST}.
 * <p>
 * The {@code stateChange} of any {@code ItemEvent} instance takes one of the following
 * values:
 *                     <ul>
 *                     <li> {@code ItemEvent.SELECTED}
 *                     <li> {@code ItemEvent.DESELECTED}
 *                     </ul>
 * Assigning the value different from listed above will cause an unspecified behavior.
 *
 * @author Carl Quinn
 *
 * @see java.awt.ItemSelectable
 * @see ItemListener
 * @see <a href="http://docs.oracle.com/javase/tutorial/uiswing/events/itemlistener.html">Tutorial: Writing an Item Listener</a>
 *
 * @since 1.1
 */
public class ItemEvent extends AWTEvent {

    
The first number in the range of ids used for item events.

/**
     * The first number in the range of ids used for item events.
     */
    public static final int ITEM_FIRST          = 701;

    
The last number in the range of ids used for item events.

/**
     * The last number in the range of ids used for item events.
     */
    public static final int ITEM_LAST           = 701;

    
This event id indicates that an item's state changed.

/**
     * This event id indicates that an item's state changed.
     */
    public static final int ITEM_STATE_CHANGED  = ITEM_FIRST; //Event.LIST_SELECT

    
This state-change value indicates that an item was selected.

/**
     * This state-change value indicates that an item was selected.
     */
    public static final int SELECTED = 1;

    
This state-change-value indicates that a selected item was deselected.

/**
     * This state-change-value indicates that a selected item was deselected.
     */
    public static final int DESELECTED  = 2;

    
The item whose selection state has changed.

See Also:
@serial
/**
     * The item whose selection state has changed.
     *
     * @serial
     * @see #getItem()
     */
    Object item;

    
stateChange indicates whether the item was selected or deselected. 
See Also:
@serial
/**
     * {@code stateChange} indicates whether the {@code item}
     * was selected or deselected.
     *
     * @serial
     * @see #getStateChange()
     */
    int stateChange;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = -608708132447206933L;

    
Constructs an ItemEvent object. 
 This method throws an IllegalArgumentException if source is null. 
Params:
  • source – The ItemSelectable object that originated the event
  • id –  The integer that identifies the event type. For information on allowable values, see the class description for ItemEvent
  • item –   An object -- the item affected by the event
  • stateChange –  An integer that indicates whether the item was selected or deselected. For information on allowable values, see the class description for ItemEvent
Throws:
See Also:
/**
     * Constructs an {@code ItemEvent} object.
     * <p> This method throws an
     * {@code IllegalArgumentException} if {@code source}
     * is {@code null}.
     *
     * @param source The {@code ItemSelectable} object
     *               that originated the event
     * @param id           The integer that identifies the event type.
     *                     For information on allowable values, see
     *                     the class description for {@link ItemEvent}
     * @param item   An object -- the item affected by the event
     * @param stateChange  An integer that indicates whether the item was
     *               selected or deselected.
     *                     For information on allowable values, see
     *                     the class description for {@link ItemEvent}
     * @throws IllegalArgumentException if {@code source} is null
     * @see #getItemSelectable()
     * @see #getID()
     * @see #getStateChange()
     */
    public ItemEvent(ItemSelectable source, int id, Object item, int stateChange) {
        super(source, id);
        this.item = item;
        this.stateChange = stateChange;
    }

    
Returns the originator of the event.

Returns:the ItemSelectable object that originated the event.
/**
     * Returns the originator of the event.
     *
     * @return the ItemSelectable object that originated the event.
     */
    public ItemSelectable getItemSelectable() {
        return (ItemSelectable)source;
    }

   
Returns the item affected by the event.

Returns:the item (object) that was affected by the event
/**
    * Returns the item affected by the event.
    *
    * @return the item (object) that was affected by the event
    */
    public Object getItem() {
        return item;
    }

   
Returns the type of state change (selected or deselected).

See Also:
Returns:an integer that indicates whether the item was selected
        or deselected
/**
    * Returns the type of state change (selected or deselected).
    *
    * @return an integer that indicates whether the item was selected
    *         or deselected
    *
    * @see #SELECTED
    * @see #DESELECTED
    */
    public int getStateChange() {
        return stateChange;
    }

    
Returns a parameter string identifying this item event.
This method is useful for event-logging and for debugging.

Returns:a string identifying the event and its attributes
/**
     * Returns a parameter string identifying this item event.
     * This method is useful for event-logging and for debugging.
     *
     * @return a string identifying the event and its attributes
     */
    public String paramString() {
        String typeStr;
        switch(id) {
          case ITEM_STATE_CHANGED:
              typeStr = "ITEM_STATE_CHANGED";
              break;
          default:
              typeStr = "unknown type";
        }

        String stateStr;
        switch(stateChange) {
          case SELECTED:
              stateStr = "SELECTED";
              break;
          case DESELECTED:
              stateStr = "DESELECTED";
              break;
          default:
              stateStr = "unknown type";
        }
        return typeStr + ",item="+item + ",stateChange="+stateStr;
    }

}