Module java.desktop

Class 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 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