public class FocusEvent extends ComponentEvent
FocusListener or
FocusAdapter object which registered to receive such events
using the Component's addFocusListener method. (
FocusAdapter objects implement the FocusListener
interface.) Each such listener object gets this FocusEvent when
the event occurs.
There are two levels of focus events: permanent and temporary. Permanent focus change events occur when focus is directly moved from one Component to another, such as through a call to requestFocus() or as the user uses the TAB key to traverse Components. Temporary focus change events occur when focus is temporarily lost for a Component as the indirect result of another operation, such as Window deactivation or a Scrollbar drag. In this case, the original focus state will automatically be restored once that operation is finished, or, for the case of Window deactivation, when the Window is reactivated. Both permanent and temporary focus events are delivered using the FOCUS_GAINED and FOCUS_LOST event ids; the level may be distinguished in the event using the isTemporary() method.
An unspecified behavior will be caused if the id parameter
of any particular FocusEvent instance is not
in the range from FOCUS_FIRST to FOCUS_LAST.
FocusAdapter,
FocusListener,
Tutorial: Writing a Focus Listener,
Serialized Form| Modifier and Type | Field and Description |
|---|---|
static int |
FOCUS_FIRST
The first number in the range of ids used for focus events.
|
static int |
FOCUS_GAINED
This event indicates that the Component is now the focus owner.
|
static int |
FOCUS_LAST
The last number in the range of ids used for focus events.
|
static int |
FOCUS_LOST
This event indicates that the Component is no longer the focus owner.
|
COMPONENT_FIRST, COMPONENT_HIDDEN, COMPONENT_LAST, COMPONENT_MOVED, COMPONENT_RESIZED, COMPONENT_SHOWNACTION_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_MASKsource| Constructor and Description |
|---|
FocusEvent(Component source,
int id)
Constructs a
FocusEvent object and identifies it
as a permanent change in focus. |
FocusEvent(Component source,
int id,
boolean temporary)
Constructs a
FocusEvent object and identifies
whether or not the change is temporary. |
FocusEvent(Component source,
int id,
boolean temporary,
Component opposite)
Constructs a
FocusEvent object with the
specified temporary state and opposite Component. |
| Modifier and Type | Method and Description |
|---|---|
Component |
getOppositeComponent()
Returns the other Component involved in this focus change.
|
boolean |
isTemporary()
Identifies the focus change event as temporary or permanent.
|
String |
paramString()
Returns a parameter string identifying this event.
|
getComponentgetSourcepublic static final int FOCUS_FIRST
public static final int FOCUS_LAST
public static final int FOCUS_GAINED
public static final int FOCUS_LOST
public FocusEvent(Component source, int id, boolean temporary, Component opposite)
FocusEvent object with the
specified temporary state and opposite Component.
The opposite Component is the other
Component involved in this focus change.
For a FOCUS_GAINED event, this is the
Component that lost focus. For a
FOCUS_LOST event, this is the Component
that gained focus. If this focus change occurs with a native
application, with a Java application in a different VM,
or with no other Component, then the opposite
Component is null.
This method throws an
IllegalArgumentException if source
is null.
source - The Component that originated the eventid - An integer indicating the type of event.
For information on allowable values, see
the class description for FocusEventtemporary - Equals true if the focus change is temporary;
false otherwiseopposite - The other Component involved in the focus change,
or nullIllegalArgumentException - if source equals nullEventObject.getSource(),
AWTEvent.getID(),
isTemporary(),
getOppositeComponent()public FocusEvent(Component source, int id, boolean temporary)
FocusEvent object and identifies
whether or not the change is temporary.
This method throws an
IllegalArgumentException if source
is null.
source - The Component that originated the eventid - An integer indicating the type of event.
For information on allowable values, see
the class description for FocusEventtemporary - Equals true if the focus change is temporary;
false otherwiseIllegalArgumentException - if source equals nullEventObject.getSource(),
AWTEvent.getID(),
isTemporary()public FocusEvent(Component source, int id)
FocusEvent object and identifies it
as a permanent change in focus.
This method throws an
IllegalArgumentException if source
is null.
source - The Component that originated the eventid - An integer indicating the type of event.
For information on allowable values, see
the class description for FocusEventIllegalArgumentException - if source equals nullEventObject.getSource(),
AWTEvent.getID()public boolean isTemporary()
true if the focus change is temporary;
false otherwisepublic Component getOppositeComponent()
public String paramString()
paramString in class ComponentEvent Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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