java.awt.event: public class: ItemEvent

java.awt.event
public class: ItemEvent [javadoc | source]

java.lang.Object
   java.util.EventObject
      java.awt.AWTEvent
         java.awt.event.ItemEvent

All Implemented Interfaces:
Serializable

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 {@code id} parameter of any particular {@code ItemEvent} instance is not in the range from {@code ITEM_FIRST} to {@code ITEM_LAST}.

The {@code stateChange} of any {@code ItemEvent} instance takes one of the following values:

{@code ItemEvent.SELECTED}
{@code ItemEvent.DESELECTED}

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

Also see:

java.awt.ItemSelectable

ItemListener

Tutorial: Writing an Item Listener

author: Carl - Quinn

since: 1.1 -

Field Summary
public static final int	ITEM_FIRST	The first number in the range of ids used for item events.
public static final int	ITEM_LAST	The last number in the range of ids used for item events.
public static final int	ITEM_STATE_CHANGED	This event id indicates that an item's state changed.
public static final int	SELECTED	This state-change value indicates that an item was selected.
public static final int	DESELECTED	This state-change-value indicates that a selected item was deselected.
Object	item	The item whose selection state has changed. Also see: getItem() serial:
int	stateChange	`stateChange` indicates whether the `item` was selected or deselected. Also see: getStateChange() serial:

Fields inherited from java.awt.AWTEvent:
id, consumed, focusManagerIsDispatching, isPosted, COMPONENT_EVENT_MASK, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, WINDOW_EVENT_MASK, ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, ITEM_EVENT_MASK, TEXT_EVENT_MASK, INPUT_METHOD_EVENT_MASK, INPUT_METHODS_ENABLED_MASK, PAINT_EVENT_MASK, INVOCATION_EVENT_MASK, HIERARCHY_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, WINDOW_STATE_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, RESERVED_ID_MAX

Fields inherited from java.awt.AWTEvent:

id, consumed, focusManagerIsDispatching, isPosted, COMPONENT_EVENT_MASK, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, WINDOW_EVENT_MASK, ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, ITEM_EVENT_MASK, TEXT_EVENT_MASK, INPUT_METHOD_EVENT_MASK, INPUT_METHODS_ENABLED_MASK, PAINT_EVENT_MASK, INVOCATION_EVENT_MASK, HIERARCHY_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, WINDOW_STATE_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, RESERVED_ID_MAX

Fields inherited from java.util.EventObject:
source

Constructor:

Constructor:
public ItemEvent(ItemSelectable source, int id, Object item, int stateChange) { super(source, id); this.item = item; this.stateChange = stateChange; } Constructs an `ItemEvent` object. This method throws an `IllegalArgumentException` if `source` is `null`. Parameters: `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: `IllegalArgumentException` - if `source` is null Also see: getItemSelectable() getID() getStateChange()

 public ItemEvent(ItemSelectable source,
    int id,
    Object item,
    int stateChange) {
                                                                                                                                                                                                                              
        super(source, id);
        this.item = item;
        this.stateChange = stateChange;
}

ItemEvent

This method throws an IllegalArgumentException if source is null.

Parameters:

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:

IllegalArgumentException - if source is null

Also see:

getItemSelectable()

getID()

getStateChange()

Method from java.awt.event.ItemEvent Summary:
getItem, getItemSelectable, getStateChange, paramString

Methods from java.awt.AWTEvent:
consume, convertToOld, copyPrivateDataInto, dispatched, getID, isConsumed, paramString, setSource, toString

Methods from java.util.EventObject:
getSource, toString

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from java.awt.event.ItemEvent Detail:
public Object getItem() { return item; } Returns the item affected by the event.
public ItemSelectable getItemSelectable() { return (ItemSelectable)source; } Returns the originator of the event.
public int getStateChange() { return stateChange; } Returns the type of state change (selected or deselected).
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; } Returns a parameter string identifying this item event. This method is useful for event-logging and for debugging.

Method from java.awt.event.ItemEvent Detail:

 public Object getItem() {
        return item;
}

Returns the item affected by the event.

 public ItemSelectable getItemSelectable() {
        return (ItemSelectable)source;
}

Returns the originator of the event.

 public int getStateChange() {
        return stateChange;
}

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

 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;
}

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