Class ActionEvent
- java.lang.Object
-
- java.util.EventObject
-
- java.awt.AWTEvent
-
- java.awt.event.ActionEvent
- All Implemented Interfaces:
Serializable
public class ActionEvent extends AWTEvent
A semantic event which indicates that a component-defined action occurred. This high-level event is generated by a component (such as a Button
) when the component-specific action occurs (such as being pressed). The event is passed to every ActionListener
object that registered to receive such events using the component's addActionListener
method.
Note: To invoke an ActionEvent
on a Button
using the keyboard, use the Space bar.
The object that implements the ActionListener
interface gets this ActionEvent
when the event occurs. The listener is therefore spared the details of processing individual mouse movements and mouse clicks, and can instead process a "meaningful" (semantic) event like "button pressed".
An unspecified behavior will be caused if the id
parameter of any particular ActionEvent
instance is not in the range from ACTION_FIRST
to ACTION_LAST
.
- Since:
- 1.1
- See Also:
-
ActionListener
, Tutorial: How to Write an Action Listener, Serialized Form
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static int | ACTION_FIRST | The first number in the range of ids used for action events. |
static int | ACTION_LAST | The last number in the range of ids used for action events. |
static int | ACTION_PERFORMED | This event id indicates that a meaningful action occurred. |
static int | ALT_MASK | The alt modifier. |
static int | CTRL_MASK | The control modifier. |
static int | META_MASK | The meta modifier. |
static int | SHIFT_MASK | The shift modifier. |
Fields declared in 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 declared in class java.util.EventObject
source
Constructor Summary
Constructor | Description |
---|---|
ActionEvent(Object source,
int id,
String command) | Constructs an |
ActionEvent(Object source,
int id,
String command,
int modifiers) | Constructs an |
ActionEvent(Object source,
int id,
String command,
long when,
int modifiers) | Constructs an |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
String | getActionCommand() | Returns the command string associated with this action. |
int | getModifiers() | Returns the modifier keys held down during this action event. |
long | getWhen() | Returns the timestamp of when this event occurred. |
String | paramString() | Returns a parameter string identifying this action event. |
Methods declared in class java.awt.AWTEvent
consume, getID, isConsumed, setSource, toString
Methods declared in class java.util.EventObject
getSource
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Field Detail
SHIFT_MASK
public static final int SHIFT_MASK
The shift modifier. An indicator that the shift key was held down during the event.
- See Also:
- Constant Field Values
CTRL_MASK
public static final int CTRL_MASK
The control modifier. An indicator that the control key was held down during the event.
- See Also:
- Constant Field Values
META_MASK
public static final int META_MASK
The meta modifier. An indicator that the meta key was held down during the event.
- See Also:
- Constant Field Values
ALT_MASK
public static final int ALT_MASK
The alt modifier. An indicator that the alt key was held down during the event.
- See Also:
- Constant Field Values
ACTION_FIRST
public static final int ACTION_FIRST
The first number in the range of ids used for action events.
- See Also:
- Constant Field Values
ACTION_LAST
public static final int ACTION_LAST
The last number in the range of ids used for action events.
- See Also:
- Constant Field Values
ACTION_PERFORMED
@Native public static final int ACTION_PERFORMED
This event id indicates that a meaningful action occurred.
- See Also:
- Constant Field Values
Constructor Detail
ActionEvent
public ActionEvent(Object source, int id, String command)
Constructs an ActionEvent
object.
This method throws an IllegalArgumentException
if source
is null
. A null command
string is legal, but not recommended.
- Parameters:
-
source
- The object that originated the event -
id
- An integer that identifies the event. For information on allowable values, see the class description forActionEvent
-
command
- A string that may specify a command (possibly one of several) associated with the event - Throws:
-
IllegalArgumentException
- ifsource
is null - See Also:
-
EventObject.getSource()
,AWTEvent.getID()
,getActionCommand()
ActionEvent
public ActionEvent(Object source, int id, String command, int modifiers)
Constructs an ActionEvent
object with modifier keys.
This method throws an IllegalArgumentException
if source
is null
. A null command
string is legal, but not recommended.
- Parameters:
-
source
- The object that originated the event -
id
- An integer that identifies the event. For information on allowable values, see the class description forActionEvent
-
command
- A string that may specify a command (possibly one of several) associated with the event -
modifiers
- The modifier keys down during event (shift, ctrl, alt, meta). Passing negative parameter is not recommended. Zero value means that no modifiers were passed - Throws:
-
IllegalArgumentException
- ifsource
is null - See Also:
-
EventObject.getSource()
,AWTEvent.getID()
,getActionCommand()
,getModifiers()
ActionEvent
public ActionEvent(Object source, int id, String command, long when, int modifiers)
Constructs an ActionEvent
object with the specified modifier keys and timestamp.
This method throws an IllegalArgumentException
if source
is null
. A null command
string is legal, but not recommended.
- Parameters:
-
source
- The object that originated the event -
id
- An integer that identifies the event. For information on allowable values, see the class description forActionEvent
-
command
- A string that may specify a command (possibly one of several) associated with the event -
modifiers
- The modifier keys down during event (shift, ctrl, alt, meta). Passing negative parameter is not recommended. Zero value means that no modifiers were passed -
when
- A long that gives the time the event occurred. Passing negative or zero value is not recommended - Throws:
-
IllegalArgumentException
- ifsource
is null - Since:
- 1.4
- See Also:
-
EventObject.getSource()
,AWTEvent.getID()
,getActionCommand()
,getModifiers()
,getWhen()
Method Detail
getActionCommand
public String getActionCommand()
Returns the command string associated with this action. This string allows a "modal" component to specify one of several commands, depending on its state. For example, a single button might toggle between "show details" and "hide details". The source object and the event would be the same in each case, but the command string would identify the intended action.
Note that if a null
command string was passed to the constructor for this ActionEvent
, this this method returns null
.
- Returns:
- the string identifying the command for this event
getWhen
public long getWhen()
Returns the timestamp of when this event occurred. Because an ActionEvent is a high-level, semantic event, the timestamp is typically the same as an underlying InputEvent.
- Returns:
- this event's timestamp
- Since:
- 1.4
getModifiers
public int getModifiers()
Returns the modifier keys held down during this action event.
- Returns:
- the bitwise-or of the modifier constants
paramString
public String paramString()
Returns a parameter string identifying this action event. This method is useful for event-logging and for debugging.
- Overrides:
-
paramString
in classAWTEvent
- Returns:
- a string identifying the event and its associated command