| java.awt.event.ComponentEvent
 java.awt.event.FocusEvent
| FocusEvent | | public class FocusEvent extends ComponentEvent (Code) | | A low-level event which indicates that a Component has gained or lost the
input focus. This low-level event is generated by a Component (such as a
TextField). The event is passed to every 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.
See Also: FocusAdapter
See Also: FocusListener
See Also: Tutorial: Writing a Focus Listener
author:
Carl Quinn
author:
Amy Fowler
version:
1.41 06/05/07
since:
1.1 |
| Field Summary | |
| final public static int | FOCUS_FIRST
The first number in the range of ids used for focus events. | | final public static int | FOCUS_GAINED
This event indicates that the Component is now the focus owner. | | final public static int | FOCUS_LAST
The last number in the range of ids used for focus events. | | final public static int | FOCUS_LOST
This event indicates that the Component is no longer the focus owner. | | transient Component | opposite
The other Component involved in this focus change. | | boolean | temporary
A focus event can have two different levels, permanent and temporary. |
| Constructor Summary | |
| public | FocusEvent(Component source, int id, boolean temporary, Component opposite)
Constructs a 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. | | public | FocusEvent(Component source, int id, boolean temporary)
Constructs a FocusEvent object and identifies
whether or not the change is temporary.
Note that passing in an invalid id results in
unspecified behavior. | | public | FocusEvent(Component source, int id)
Constructs a FocusEvent object and identifies it
as a permanent change in focus.
Note that passing in an invalid id results in
unspecified behavior. |
| FOCUS_FIRST | | final public static int FOCUS_FIRST(Code) | | The first number in the range of ids used for focus events.
|
| FOCUS_GAINED | | final public static int FOCUS_GAINED(Code) | | This event indicates that the Component is now the focus owner.
|
| FOCUS_LAST | | final public static int FOCUS_LAST(Code) | | The last number in the range of ids used for focus events.
|
| FOCUS_LOST | | final public static int FOCUS_LOST(Code) | | This event indicates that the Component is no longer the focus owner.
|
| opposite | | transient Component opposite(Code) | | 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, a Java application in a different VM, or with
no other Component, then the opposite Component is null.
See Also: FocusEvent.getOppositeComponent
since:
1.4 |
| temporary | | boolean temporary(Code) | | A focus event can have two different levels, permanent and temporary.
It will be set to true if some operation takes away the focus
temporarily and intends on getting it back once the event is completed.
Otherwise it will be set to false.
See Also: FocusEvent.isTemporary |
| FocusEvent | | public FocusEvent(Component source, int id, boolean temporary, Component opposite)(Code) | | Constructs a 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.
Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.
Parameters:
source - the Component that originated the event
Parameters:
id - FOCUS_GAINED or FOCUS_LOST
Parameters:
temporary - true if the focus change is temporary;false otherwise
Parameters:
opposite - the other Component involved in the focus change,or null
throws:
IllegalArgumentException - if source is null
since:
1.4 |
| FocusEvent | | public FocusEvent(Component source, int id, boolean temporary)(Code) | | Constructs a FocusEvent object and identifies
whether or not the change is temporary.
Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.
Parameters:
source - the Component that originated the event
Parameters:
id - an integer indicating the type of event
Parameters:
temporary - true if the focus change is temporary;false otherwise
throws:
IllegalArgumentException - if source is null |
| FocusEvent | | public FocusEvent(Component source, int id)(Code) | | Constructs a FocusEvent object and identifies it
as a permanent change in focus.
Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.
Parameters:
source - the Component that originated the event
Parameters:
id - an integer indicating the type of event
throws:
IllegalArgumentException - if source is null |
| getOppositeComponent | | public Component getOppositeComponent()(Code) | | Returns 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 context, or with no other Component, then null is
returned.
the other Component involved in the focus change, or null
since:
1.4 |
| isTemporary | | public boolean isTemporary()(Code) | | Identifies the focus change event as temporary or permanent.
true if the focus change is temporary;false otherwise |
| paramString | | public String paramString()(Code) | | Returns a parameter string identifying this event.
This method is useful for event-logging and for debugging.
a string identifying the event and its attributes |
|
|