Полезная информация

Java in a Nutshell

Previous Chapter 20
The java.awt.event Package
Next
 

20.15 java.awt.event.ItemEvent (JDK 1.1)

An event of this type indicates that an item within an ItemSelectable component has had its selection state changed.

getItemSelectable() is a convenient alternative to getSource() that returns the ItemSelectable object that originated the event. getItem() returns an object that represents the item that was selected or deselected.

getID() returns the type of the ItemEvent. The standard AWT components always generate item events of type ITEM_STATE_CHANGED. The getStateChange() method returns the new selection state of the item: it returns one of the constants SELECTED or DESELECTED. (This value can be misleading for Checkbox components that are part of a CheckboxGroup. If the user attempts to deselect a selected component, a DESELECTED event is delivered, but the CheckboxGroup immediately re-selects the component to enforce its requirement that at least one Checkbox be selected at all times.)

public class ItemEvent extends AWTEvent {
    // Public Constructor
            public ItemEvent(ItemSelectable source, int id, Object item, int stateChange);
    // Constants
            public static final int DESELECTED;
            public static final int ITEM_FIRST;
            public static final int ITEM_LAST;
            public static final int ITEM_STATE_CHANGED;
            public static final int SELECTED;
    // Public Instance Methods
            public Object getItem();
            public ItemSelectable getItemSelectable();
            public int getStateChange();
            public String paramString();  // Overrides AWTEvent
}

Hierarchy:

Object->EventObject(Serializable)->AWTEvent->ItemEvent

Passed To:

AWTEventMulticaster.itemStateChanged(), Checkbox.processItemEvent(), CheckboxMenuItem.processItemEvent(), Choice.processItemEvent(), ItemListener.itemStateChanged(), List.processItemEvent()


Previous Home Next
java.awt.event.InputEvent (JDK 1.1) Book Index java.awt.event.ItemListener (JDK 1.1)

Java in a Nutshell Java Language Reference Java AWT Java Fundamental Classes Exploring Java