Module java.desktop
Package java.awt.event

Class ItemEvent

  • All Implemented Interfaces:
    Serializable

    public classItemEventextendsAWTEvent
    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 everyItemListener object which registered to receive such events using the component'saddItemListener method.

    The object that implements theItemListener interface gets thisItemEvent 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 theid parameter of any particularItemEvent instance is not in the range fromITEM_FIRST toITEM_LAST.

    ThestateChange of anyItemEvent 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 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 anItemEvent object.

        This method throws anIllegalArgumentException ifsource isnull.

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