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ActionEvent (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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JavaTM 2 Platform
Std. Ed. v1.4.1
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java.awt.event
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 occured. 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 every ActionListener object that registered to receive such events using the component's addActionListener method.

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".

Since:
1.1
See Also:
ActionListener, Tutorial: Java 1.1 Event Model, Reference: The Java Class Libraries (update file), Serialized Form

Field Summary
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 occured.
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 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
ActionEvent(Object source, int id, String command)
          Constructs an ActionEvent object.
ActionEvent(Object source, int id, String command, int modifiers)
          Constructs an ActionEvent object with modifier keys.
ActionEvent(Object source, int id, String command, long when, int modifiers)
          Constructs an ActionEvent object with the specified modifier keys and timestamp.
 
Method Summary
 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 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

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

public static final int ACTION_PERFORMED
This event id indicates that a meaningful action occured.

See Also:
Constant Field Values
Constructor Detail

ActionEvent

public ActionEvent(Object source,
                   int id,
                   String command)
Constructs an ActionEvent object.

Note that passing in an invalid id results in unspecified behavior.

Parameters:
source - the object that originated the event
id - an integer that identifies the event
command - a string that may specify a command (possibly one of several) associated with the event

ActionEvent

public ActionEvent(Object source,
                   int id,
                   String command,
                   int modifiers)
Constructs an ActionEvent object with modifier keys.

Note that passing in an invalid id results in unspecified behavior.

Parameters:
source - the object that originated the event
id - an integer that identifies the event
command - a string that may specify a command (possibly one of several) associated with the event
modifiers - the modifier keys held down during this action

ActionEvent

public ActionEvent(Object source,
                   int id,
                   String command,
                   long when,
                   int modifiers)
Constructs an ActionEvent object with the specified modifier keys and timestamp.

Note that passing in an invalid id results in unspecified behavior.

Parameters:
source - the object that originated the event
id - an integer that identifies the event
command - a string that may specify a command (possibly one of several) associated with the event
when - the time the event occurred
modifiers - the modifier keys held down during this action
Since:
1.4
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.

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 class AWTEvent
Returns:
a string identifying the event and its associated command
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JavaTM 2 Platform
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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.