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.

Every FocusEvent records its cause - the reason why this event was generated. The cause is assigned during the focus event creation and may be retrieved by calling getCause.

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.

Nested and Inner Type Summary

Modifier and Type	Class and Description
public static enum	FocusEvent.Cause This enum represents the cause of a `FocusEvent`- the reason why it occurred.

Field Summary

Modifier and Type	Field and Description
private final FocusEvent.Cause	cause A focus event has the reason why this event was generated.
public static final int	FOCUS_FIRST The first number in the range of ids used for focus events.
public static final int	FOCUS_GAINED This event indicates that the Component is now the focus owner.
public static final int	FOCUS_LAST The last number in the range of ids used for focus events.
public static final int	FOCUS_LOST This event indicates that the Component is no longer the focus owner.
pack-priv transient Component	opposite The other Component involved in this focus change.
private static final long	serialVersionUID Hides java.awt.event.ComponentEvent.serialVersionUID. Use serialVersionUID from JDK 1.1 for interoperability.
pack-priv boolean	temporary A focus event can have two different levels, permanent and temporary.

Inherited from java.awt.event.ComponentEvent:: COMPONENT_FIRST COMPONENT_HIDDEN COMPONENT_LAST COMPONENT_MOVED COMPONENT_RESIZED COMPONENT_SHOWN

Constructor Summary

Access	Constructor and Description
public	FocusEvent(Component The `Component` that originated the event source, int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` id, boolean Equals `true` if the focus change is temporary; `false` otherwise temporary, Component The other Component involved in the focus change, or `null` opposite) Constructs a `FocusEvent` object with the specified temporary state, opposite `Component` and the `Cause.UNKNOWN` cause.
public	FocusEvent(Component The `Component` that originated the event source, int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` id, boolean Equals `true` if the focus change is temporary; `false` otherwise temporary, Component The other Component involved in the focus change, or `null` opposite, FocusEvent.Cause The focus event cause. cause) Constructs a `FocusEvent` object with the specified temporary state, opposite `Component` and the cause.
public	FocusEvent(Component The `Component` that originated the event source, int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` id, boolean Equals `true` if the focus change is temporary; `false` otherwise temporary) Constructs a `FocusEvent` object and identifies whether or not the change is temporary.
public	FocusEvent(Component The `Component` that originated the event source, int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` id) Constructs a `FocusEvent` object and identifies it as a permanent change in focus.

Method Summary

Modifier and Type	Method and Description
public final FocusEvent.Cause	Returns: one of `Cause` values getCause() Returns the event cause.
public Component	Returns: the other Component involved in the focus change, or null getOppositeComponent() Returns the other Component involved in this focus change.
public boolean	Returns: `true` if the focus change is temporary; `false` otherwise isTemporary() Identifies the focus change event as temporary or permanent.
public String	Returns: a string identifying the event and its attributes paramString() Overrides java.awt.event.ComponentEvent.paramString. Returns a parameter string identifying this event.
pack-priv Object	Returns: a newly created object from deserialized data readResolve() Checks if this deserialized `FocusEvent` instance is compatible with the current specification which implies that focus event has non-null `cause` value.

Inherited from java.awt.event.ComponentEvent:: getComponent

Field Detail

cause back to summary

cause	back to summary
private final FocusEvent.Cause cause A focus event has the reason why this event was generated. The cause is set during the focus event creation. Since 9 See Also `getCause()`

private final FocusEvent.Cause cause

A focus event has the reason why this event was generated. The cause is set during the focus event creation.

Since: 9
See Also: getCause()

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

FOCUS_GAINED	back to summary
public static final int FOCUS_GAINED This event indicates that the Component is now the focus owner.

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

FOCUS_LOST	back to summary
public static final int FOCUS_LOST This event indicates that the Component is no longer the focus owner.

opposite back to summary

opposite	back to summary
pack-priv transient Component opposite 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. Since 1.4 See Also `getOppositeComponent`

pack-priv transient Component opposite

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.

Since: 1.4
See Also: getOppositeComponent

serialVersionUID	back to summary
private static final long serialVersionUID Hides java.awt.event.ComponentEvent.serialVersionUID. Use serialVersionUID from JDK 1.1 for interoperability. Annotations @Serial

serialVersionUID

back to summary

private static final long serialVersionUID

Hides java.awt.event.ComponentEvent.serialVersionUID.

Use serialVersionUID from JDK 1.1 for interoperability.

Annotations

@Serial

temporary back to summary

temporary	back to summary
pack-priv boolean temporary 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 `isTemporary`

pack-priv boolean temporary

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: isTemporary

Constructor Detail

FocusEvent back to summary

FocusEvent	back to summary
public FocusEvent(Component source, int id, boolean temporary, Component opposite) Constructs a `FocusEvent` object with the specified temporary state, opposite `Component` and the `Cause.UNKNOWN` cause. 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`. Parameters source:Component The `Component` that originated the event id:int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` temporary:boolean Equals `true` if the focus change is temporary; `false` otherwise opposite:Component The other Component involved in the focus change, or `null` Exceptions IllegalArgumentException: if `source` equals `null` Since 1.4 See Also `getSource()`, `getID()`, `isTemporary()`, `getOppositeComponent()`, `Cause#UNKNOWN`

public FocusEvent(Component source, int id, boolean temporary, Component opposite)

Constructs a FocusEvent object with the specified temporary state, opposite Component and the Cause.UNKNOWN cause. 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.

Parameters

source:Component: The Component that originated the event
id:int: An integer indicating the type of event. For information on allowable values, see the class description for FocusEvent
temporary:boolean: Equals true if the focus change is temporary; false otherwise
opposite:Component: The other Component involved in the focus change, or null

Exceptions

IllegalArgumentException:: if source equals null

Since

1.4

FocusEvent back to summary

FocusEvent	back to summary
public FocusEvent(Component source, int id, boolean temporary, Component opposite, FocusEvent.Cause cause) Constructs a `FocusEvent` object with the specified temporary state, opposite `Component` and the cause. 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` or `cause` is `null`. Parameters source:Component The `Component` that originated the event id:int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` temporary:boolean Equals `true` if the focus change is temporary; `false` otherwise opposite:Component The other Component involved in the focus change, or `null` cause:FocusEvent.Cause The focus event cause. Exceptions IllegalArgumentException: if `source` equals `null` or if `cause` equals `null` Since 9 See Also `getSource()`, `getID()`, `isTemporary()`, `getOppositeComponent()`, `Cause`

public FocusEvent(Component source, int id, boolean temporary, Component opposite, FocusEvent.Cause cause)

Constructs a FocusEvent object with the specified temporary state, opposite Component and the cause. 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 or cause is null.

Parameters

source:Component: The Component that originated the event
id:int: An integer indicating the type of event. For information on allowable values, see the class description for FocusEvent
temporary:boolean: Equals true if the focus change is temporary; false otherwise
opposite:Component: The other Component involved in the focus change, or null
cause:FocusEvent.Cause: The focus event cause.

Exceptions

IllegalArgumentException:: if source equals null or if cause equals null

Since

FocusEvent back to summary

FocusEvent	back to summary
public FocusEvent(Component source, int id, boolean temporary) Constructs a `FocusEvent` object and identifies whether or not the change is temporary. This method throws an `IllegalArgumentException` if `source` is `null`. Parameters source:Component The `Component` that originated the event id:int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` temporary:boolean Equals `true` if the focus change is temporary; `false` otherwise Exceptions IllegalArgumentException: if `source` equals `null` See Also `getSource()`, `getID()`, `isTemporary()`

public FocusEvent(Component source, int id, boolean temporary)

Constructs a FocusEvent object and identifies whether or not the change is temporary.

This method throws an IllegalArgumentException if source is null.

Parameters

source:Component: The Component that originated the event
id:int: An integer indicating the type of event. For information on allowable values, see the class description for FocusEvent
temporary:boolean: Equals true if the focus change is temporary; false otherwise

Exceptions

IllegalArgumentException:: if source equals null

FocusEvent back to summary

FocusEvent	back to summary
public FocusEvent(Component source, int id) Constructs a `FocusEvent` object and identifies it as a permanent change in focus. This method throws an `IllegalArgumentException` if `source` is `null`. Parameters source:Component The `Component` that originated the event id:int An integer indicating the type of event. For information on allowable values, see the class description for `FocusEvent` Exceptions IllegalArgumentException: if `source` equals `null` See Also `getSource()`, `getID()`

public FocusEvent(Component source, int id)

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

This method throws an IllegalArgumentException if source is null.

Parameters

source:Component: The Component that originated the event
id:int: An integer indicating the type of event. For information on allowable values, see the class description for FocusEvent

Exceptions

IllegalArgumentException:: if source equals null

See Also

getSource(), getID()

Method Detail

getCause back to summary

getCause	back to summary
public final FocusEvent.Cause getCause() Returns the event cause. Returns:FocusEvent.Cause one of `Cause` values Since 9

public final FocusEvent.Cause getCause()

Returns the event cause.

Returns:FocusEvent.Cause: one of Cause values
Since: 9

getOppositeComponent	back to summary
public Component getOppositeComponent() 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 with no other Component, then null is returned. Returns:Component the other Component involved in the focus change, or null Since 1.4

getOppositeComponent

back to summary

public Component getOppositeComponent()

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 with no other Component, then null is returned.

Returns:Component: the other Component involved in the focus change, or null
Since: 1.4

isTemporary back to summary

isTemporary	back to summary
public boolean isTemporary() Identifies the focus change event as temporary or permanent. Returns:boolean `true` if the focus change is temporary; `false` otherwise

public boolean isTemporary()

Identifies the focus change event as temporary or permanent.

Returns:boolean: true if the focus change is temporary; false otherwise

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

paramString

back to summary

public String paramString()

Overrides java.awt.event.ComponentEvent.paramString.

Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Returns:String: a string identifying the event and its attributes

readResolve back to summary

readResolve	back to summary
pack-priv Object readResolve() throws ObjectStreamException Checks if this deserialized `FocusEvent` instance is compatible with the current specification which implies that focus event has non-null `cause` value. If the check fails a new `FocusEvent` instance is returned which `cause` field equals to `Cause#UNKNOWN` and its other fields have the same values as in this `FocusEvent` instance. Returns:Object a newly created object from deserialized data Annotations @Serial Exceptions ObjectStreamException: if a new object replacing this object could not be created Since 9 See Also `cause`

pack-priv Object readResolve() throws ObjectStreamException

Checks if this deserialized FocusEvent instance is compatible with the current specification which implies that focus event has non-null cause value. If the check fails a new FocusEvent instance is returned which cause field equals to Cause#UNKNOWN and its other fields have the same values as in this FocusEvent instance.

Returns:Object

a newly created object from deserialized data

Annotations

@Serial

Exceptions

ObjectStreamException:: if a new object replacing this object could not be created

Since

See Also

cause

java.awt.event back to summary

public final Enum FocusEvent.Cause

Class Inheritance

extends Enum<FocusEvent.Cause>

java.lang.Object
java.lang.Enum
java.awt.event.FocusEvent.Cause

This enum represents the cause of a FocusEvent- the reason why it occurred. Possible reasons include mouse events, keyboard focus traversal, window activation. If no cause is provided then the reason is UNKNOWN.

Since: 9

Field Summary

Modifier and Type	Field and Description
public static final FocusEvent.Cause	ACTIVATION An activation of a toplevel window.
public static final FocusEvent.Cause	CLEAR_GLOBAL_FOCUS_OWNER Clearing global focus owner.
public static final FocusEvent.Cause	MOUSE_EVENT An activating mouse event.
public static final FocusEvent.Cause	ROLLBACK Restoring focus after a focus request has been rejected.
public static final FocusEvent.Cause	TRAVERSAL A focus traversal action with unspecified direction.
public static final FocusEvent.Cause	TRAVERSAL_BACKWARD A backward focus traversal action.
public static final FocusEvent.Cause	TRAVERSAL_DOWN A down-cycle focus traversal action.
public static final FocusEvent.Cause	TRAVERSAL_FORWARD A forward focus traversal action.
public static final FocusEvent.Cause	TRAVERSAL_UP An up-cycle focus traversal action.
public static final FocusEvent.Cause	UNEXPECTED A system action causing an unexpected focus change.
public static final FocusEvent.Cause	UNKNOWN The default value.

Constructor Summary

Access	Constructor and Description
private	Cause()

Method Summary

Modifier and Type	Method and Description
public static FocusEvent.Cause	valueOf(String name)
public static FocusEvent.Cause[]	values()

Inherited from java.lang.Enum:: clone compareTo describeConstable equals finalize getDeclaringClass hashCode name ordinal toString valueOf

Field Detail

ACTIVATION	back to summary
public static final FocusEvent.Cause ACTIVATION An activation of a toplevel window.

CLEAR_GLOBAL_FOCUS_OWNER	back to summary
public static final FocusEvent.Cause CLEAR_GLOBAL_FOCUS_OWNER Clearing global focus owner.

MOUSE_EVENT	back to summary
public static final FocusEvent.Cause MOUSE_EVENT An activating mouse event.

ROLLBACK	back to summary
public static final FocusEvent.Cause ROLLBACK Restoring focus after a focus request has been rejected.

TRAVERSAL	back to summary
public static final FocusEvent.Cause TRAVERSAL A focus traversal action with unspecified direction.

TRAVERSAL_BACKWARD	back to summary
public static final FocusEvent.Cause TRAVERSAL_BACKWARD A backward focus traversal action.

TRAVERSAL_DOWN	back to summary
public static final FocusEvent.Cause TRAVERSAL_DOWN A down-cycle focus traversal action.

TRAVERSAL_FORWARD	back to summary
public static final FocusEvent.Cause TRAVERSAL_FORWARD A forward focus traversal action.

TRAVERSAL_UP	back to summary
public static final FocusEvent.Cause TRAVERSAL_UP An up-cycle focus traversal action.

UNEXPECTED	back to summary
public static final FocusEvent.Cause UNEXPECTED A system action causing an unexpected focus change.

UNKNOWN	back to summary
public static final FocusEvent.Cause UNKNOWN The default value.

Constructor Detail

Cause	back to summary
private Cause()

Method Detail

valueOf	back to summary
public static FocusEvent.Cause valueOf(String name)

values	back to summary
public static FocusEvent.Cause[] values()

public Class FocusEvent

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

public final Enum FocusEvent.Cause

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail