java.awt.event

Class FocusEvent

java.lang.Object

java.util.EventObject

java.awt.AWTEvent

java.awt.event.ComponentEvent

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

Fields

Modifier and Type	Field and Description
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

Constructors

Constructor and Description
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

Methods

Modifier and Type	Method and Description
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