Class ItemEvent
- java.lang.Object
-
- java.util.EventObject
-
- java.awt.AWTEvent
-
- java.awt.event.ItemEvent
- All Implemented Interfaces:
Serializable
public class ItemEvent extends AWTEvent
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
- Since:
- 1.1
- See Also:
-
ItemSelectable
,ItemListener
, Tutorial: Writing an Item Listener, Serialized Form
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static int | DESELECTED | This state-change-value indicates that a selected item was deselected. |
static int | ITEM_FIRST | The first number in the range of ids used for item events. |
static int | ITEM_LAST | The last number in the range of ids used for item events. |
static int | ITEM_STATE_CHANGED | This event id indicates that an item's state changed. |
static int | SELECTED | This state-change value indicates that an item was selected. |
Fields declared in class java.awt.AWTEvent
ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK
Fields declared in class java.util.EventObject
source
Constructor Summary
Constructor | Description |
---|---|
ItemEvent(ItemSelectable source,
int id,
Object item,
int stateChange) | Constructs an |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
Object | getItem() | Returns the item affected by the event. |
ItemSelectable | getItemSelectable() | Returns the originator of the event. |
int | getStateChange() | Returns the type of state change (selected or deselected). |
String | paramString() | Returns a parameter string identifying this item event. |
Methods declared in class java.awt.AWTEvent
consume, getID, isConsumed, setSource, toString
Methods declared in class java.util.EventObject
getSource
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Field Detail
ITEM_FIRST
public static final int ITEM_FIRST
The first number in the range of ids used for item events.
- See Also:
- Constant Field Values
ITEM_LAST
public static final int ITEM_LAST
The last number in the range of ids used for item events.
- See Also:
- Constant Field Values
ITEM_STATE_CHANGED
public static final int ITEM_STATE_CHANGED
This event id indicates that an item's state changed.
- See Also:
- Constant Field Values
SELECTED
public static final int SELECTED
This state-change value indicates that an item was selected.
- See Also:
- Constant Field Values
DESELECTED
public static final int DESELECTED
This state-change-value indicates that a selected item was deselected.
- See Also:
- Constant Field Values
Constructor Detail
ItemEvent
public ItemEvent(ItemSelectable source, int id, Object item, int stateChange)
Constructs an ItemEvent
object.
This method throws an IllegalArgumentException
if source
is null
.
- Parameters:
-
source
- TheItemSelectable
object that originated the event -
id
- The integer that identifies the event type. For information on allowable values, see the class description forItemEvent
-
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 forItemEvent
- Throws:
-
IllegalArgumentException
- ifsource
is null - See Also:
-
getItemSelectable()
,AWTEvent.getID()
,getStateChange()
Method Detail
getItemSelectable
public ItemSelectable getItemSelectable()
Returns the originator of the event.
- Returns:
- the ItemSelectable object that originated the event.
getItem
public Object getItem()
Returns the item affected by the event.
- Returns:
- the item (object) that was affected by the event
getStateChange
public int getStateChange()
Returns the type of state change (selected or deselected).
- Returns:
- an integer that indicates whether the item was selected or deselected
- See Also:
-
SELECTED
,DESELECTED
paramString
public String paramString()
Returns a parameter string identifying this item event. This method is useful for event-logging and for debugging.
- Overrides:
-
paramString
in classAWTEvent
- Returns:
- a string identifying the event and its attributes