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Class java.awt.event.FocusEvent

java.lang.Object
    |
    +----java.util.EventObject
            |
            +----java.awt.AWTEvent
                    |
                    +----java.awt.event.ComponentEvent
                            |
                            +----java.awt.event.FocusEvent

public class FocusEvent
extends ComponentEvent
A low-level event which indicates that a component has gained or lost the keyboard focus. This low-level event is generated by a component (such as a text field). 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 change events: permanent and temporary. Permanent focus change events occur when focus is directly moved from one component to another, such as through calls to requestFocus() or as the user uses the Tab key to traverse components. Temporary focus change events occur when focus is temporarily gained or 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 levels may be distinguished in the event using the isTemporary() method.

See Also:
FocusAdapter, FocusListener, Tutorial: Writing a Focus Listener, Reference: The Java Class Libraries (update file)

Field Summary
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 gained the keyboard focus.
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 lost the keyboard focus.
 
Fields inherited from class java.awt.event.ComponentEvent
 COMPONENT_FIRST, COMPONENT_HIDDEN, COMPONENT_LAST, COMPONENT_MOVED, COMPONENT_RESIZED, COMPONENT_SHOWN
 
Fields inherited from class java.awt.AWTEvent
 ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK
 
Fields inherited from class java.util.EventObject
 source
 

Constructor Summary
 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)
Constructs a FocusEvent object and identifies it as a permanent change in focus.
 

Method Summary
boolean  isTemporary()
Identifies the focus change event as temporary or permanent.
String  paramString()
Returns a parameter string identifying this event.
 
Methods inherited from class java.awt.event.ComponentEvent
 getComponent, paramString
 
Methods inherited from class java.awt.AWTEvent
 consume, getID, isConsumed, paramString, toString
 
Methods inherited from class java.util.EventObject
 getSource, toString
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

FOCUS_FIRST

public static final int FOCUS_FIRST
The first number in the range of ids used for focus events.

FOCUS_LAST

public static final int FOCUS_LAST
The last number in the range of ids used for focus events.

FOCUS_GAINED

public static final int FOCUS_GAINED
This event indicates that the component gained the keyboard focus.

FOCUS_LOST

public static final int FOCUS_LOST
This event indicates that the component lost the keyboard focus.
Constructor Detail

FocusEvent

public FocusEvent(Component source,
                  int id,
                  boolean temporary)
Constructs a FocusEvent object and identifies whether or not the change is temporary.
Parameters:
source - the Component that originated the event
id - an integer indicating the type of event
temporary - a boolean, true if the focus change is temporary

FocusEvent

public FocusEvent(Component source,
                  int id)
Constructs a FocusEvent object and identifies it as a permanent change in focus.
Parameters:
source - the Component that originated the event
id - an integer indicating the type of event
Method Detail

isTemporary

public boolean isTemporary()
Identifies the focus change event as temporary or permanent.
Returns:
a boolean value, true if the focus change is temporary

paramString

public String paramString()
Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.
Returns:
a string identifying the event and its attributes
Overrides:
paramString in class ComponentEvent

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