java.awt.event
Class FocusEvent

java.lang.Object
  extended by java.util.EventObject
      extended by java.awt.AWTEvent
          extended by java.awt.event.ComponentEvent
              extended by java.awt.event.FocusEvent
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
CausedFocusEvent

public class FocusEvent
extends ComponentEvent

This class represents an event generated when a focus change occurs for a component. There are both temporary changes, such as when focus is stolen during a sroll then returned, and permanent changes, such as when the user TABs through focusable components.

Since:
1.1
See Also:
FocusAdapter, FocusListener, Serialized Form

Field Summary
static int FOCUS_FIRST
          This is the first id in the range of ids used by this class.
static int FOCUS_GAINED
          This is the event id for a focus gained event.
static int FOCUS_LAST
          This is the last id in the range of ids used by this class.
static int FOCUS_LOST
          This is the event id for a focus lost event.
 
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, 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_MASK
 
Fields inherited from class java.util.EventObject
source
 
Constructor Summary
FocusEvent(Component source, int id)
          Initializes a new instance of FocusEvent with the specified source and id.
FocusEvent(Component source, int id, boolean temporary)
          Initializes a new instance of FocusEvent with the specified source, id, and temporary status.
FocusEvent(Component source, int id, boolean temporary, Component opposite)
          Initializes a new instance of FocusEvent with the specified source, id, temporary status, and opposite counterpart.
 
Method Summary
 Component getOppositeComponent()
          Returns the component which received the opposite focus event.
 boolean isTemporary()
          This method tests whether or not the focus change is temporary or permanent.
 String paramString()
          Returns a string identifying this event.
 
Methods inherited from class java.awt.event.ComponentEvent
getComponent
 
Methods inherited from class java.awt.AWTEvent
consume, getID, isConsumed, setSource, toString
 
Methods inherited from class java.util.EventObject
getSource
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

FOCUS_FIRST

public static final int FOCUS_FIRST
This is the first id in the range of ids used by this class.

See Also:
Constant Field Values

FOCUS_LAST

public static final int FOCUS_LAST
This is the last id in the range of ids used by this class.

See Also:
Constant Field Values

FOCUS_GAINED

public static final int FOCUS_GAINED
This is the event id for a focus gained event.

See Also:
Constant Field Values

FOCUS_LOST

public static final int FOCUS_LOST
This is the event id for a focus lost event.

See Also:
Constant Field Values
Constructor Detail

FocusEvent

public FocusEvent(Component source,
                  int id,
                  boolean temporary,
                  Component opposite)
Initializes a new instance of FocusEvent with the specified source, id, temporary status, and opposite counterpart. Note that an invalid id leads to unspecified results.

Parameters:
source - the component that is gaining or losing focus
id - the event id
temporary - true if the focus change is temporary
opposite - the component receiving the opposite focus event, or null
Throws:
IllegalArgumentException - if source is null

FocusEvent

public FocusEvent(Component source,
                  int id,
                  boolean temporary)
Initializes a new instance of FocusEvent with the specified source, id, and temporary status. Note that an invalid id leads to unspecified results.

Parameters:
source - the component that is gaining or losing focus
id - the event id
temporary - true if the focus change is temporary
Throws:
IllegalArgumentException - if source is null

FocusEvent

public FocusEvent(Component source,
                  int id)
Initializes a new instance of FocusEvent with the specified source and id. Note that an invalid id leads to unspecified results.

Parameters:
source - the component that is gaining or losing focus
id - the event id
Throws:
IllegalArgumentException - if source is null
Method Detail

isTemporary

public boolean isTemporary()
This method tests whether or not the focus change is temporary or permanent.

Returns:
true if the focus change is temporary

getOppositeComponent

public Component getOppositeComponent()
Returns the component which received the opposite focus event. If this component gained focus, the opposite lost focus; likewise if this component is giving up focus, the opposite is gaining it. If this information is unknown, perhaps because the opposite is a native application, this returns null.

Returns:
the component with the focus opposite, or null
Since:
1.4

paramString

public String paramString()
Returns a string identifying this event. This is formatted as: (getID() == FOCUS_GAINED ? "FOCUS_GAINED" : "FOCUS_LOST") + (isTemporary() ? ",temporary," : ",permanent,") + "opposite=" + getOppositeComponent().

Overrides:
paramString in class ComponentEvent
Returns:
a string identifying this event