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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
Assigning the value different from listed above will cause an unspecified behavior.
Since:
1.1
See Also:
  • ItemSelectable
  • ItemListener
  • Tutorial: Writing an Item Listener
  • Serialized Form

Field Summary

Modifier and Type Field Description
static final int DESELECTED
This state-change-value indicates that a selected item was deselected.
static final int ITEM_FIRST
The first number in the range of ids used for item events.
static final int ITEM_LAST
The last number in the range of ids used for item events.
static final int ITEM_STATE_CHANGED
This event id indicates that an item's state changed.
static final int SELECTED
This state-change value indicates that an item was selected.

Fields declared in class 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
Modifier and Type Field Description
static final long ACTION_EVENT_MASK
The event mask for selecting action events.
static final long ADJUSTMENT_EVENT_MASK
The event mask for selecting adjustment events.
static final long COMPONENT_EVENT_MASK
The event mask for selecting component events.
protected boolean consumed
Controls whether or not the event is sent back down to the peer once the source has processed it - false means it's sent to the peer; true means it's not.
static final long CONTAINER_EVENT_MASK
The event mask for selecting container events.
static final long FOCUS_EVENT_MASK
The event mask for selecting focus events.
static final long HIERARCHY_BOUNDS_EVENT_MASK
The event mask for selecting hierarchy bounds events.
static final long HIERARCHY_EVENT_MASK
The event mask for selecting hierarchy events.
protected int id
The event's id.
static final long INPUT_METHOD_EVENT_MASK
The event mask for selecting input method events.
static final long INVOCATION_EVENT_MASK
The event mask for selecting invocation events.
static final long ITEM_EVENT_MASK
The event mask for selecting item events.
static final long KEY_EVENT_MASK
The event mask for selecting key events.
static final long MOUSE_EVENT_MASK
The event mask for selecting mouse events.
static final long MOUSE_MOTION_EVENT_MASK
The event mask for selecting mouse motion events.
static final long MOUSE_WHEEL_EVENT_MASK
The event mask for selecting mouse wheel events.
static final long PAINT_EVENT_MASK
The event mask for selecting paint events.
static final int RESERVED_ID_MAX
The maximum value for reserved AWT event IDs.
static final long TEXT_EVENT_MASK
The event mask for selecting text events.
static final long WINDOW_EVENT_MASK
The event mask for selecting window events.
static final long WINDOW_FOCUS_EVENT_MASK
The event mask for selecting window focus events.
static final long WINDOW_STATE_EVENT_MASK
The event mask for selecting window state events.

Fields declared in class EventObject

source
Modifier and Type Field Description
protected Object source
The object on which the Event initially occurred.

Constructor Summary

Constructor Description
ItemEvent(ItemSelectable source, int id, Object item, int stateChange)
Constructs an ItemEvent object.

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 AWTEvent

consume, getID, isConsumed, setSource, toString
Modifier and Type Method Description
protected void consume()
Consumes this event, if this event can be consumed.
int getID()
Returns the event type.
protected boolean isConsumed()
Returns whether this event has been consumed.
void setSource(Object newSource)
Retargets an event to a new source.
String toString()
Returns a String representation of this object.

Methods declared in class EventObject

getSource
Modifier and Type Method Description
Object getSource()
The object on which the Event initially occurred.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Modifier and Type Method Description
protected Object clone()
Creates and returns a copy of this object.
boolean equals(Object obj)
Indicates whether some other object is "equal to" this one.
protected void finalize()
Deprecated, for removal: This API element is subject to removal in a future version.
Finalization is deprecated and subject to removal in a future release.
final Class<?> getClass()
Returns the runtime class of this Object.
int hashCode()
Returns a hash code value for this object.
final void notify()
Wakes up a single thread that is waiting on this object's monitor.
final void notifyAll()
Wakes up all threads that are waiting on this object's monitor.
final void wait()
Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void wait(long timeoutMillis)
Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void wait(long timeoutMillis, int nanos)
Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Field Details

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 Details

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 - 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
See Also:
  • getItemSelectable()
  • AWTEvent.getID()
  • getStateChange()

Method Details

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 class AWTEvent
Returns:
a string identifying the event and its attributes

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