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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class ActionEvent - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.awt.event
Class ActionEvent

java.lang.Object
  |
  +--java.util.EventObject
        |
        +--java.awt.AWTEvent
              |
              +--java.awt.event.ActionEvent
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".

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, id, INPUT_METHOD_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_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.
 
Method Summary
 String getActionCommand()
          Returns the command string associated with this action.
 int getModifiers()
          Returns the modifier keys held down during this action event.
 String paramString()
          Returns a parameter string identifying this action event.
 
Methods inherited from class java.awt.AWTEvent
consume, finalize, getID, isConsumed, toString
 
Methods inherited from class java.util.EventObject
getSource
 
Methods inherited from class java.lang.Object
clone, equals, 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.

CTRL_MASK

public static final int CTRL_MASK
The control modifier. An indicator that the control key was held down during the event.

META_MASK

public static final int META_MASK
The meta modifier. An indicator that the meta key was held down during the event.

ALT_MASK

public static final int ALT_MASK
The alt modifier. An indicator that the alt key was held down during the event.

ACTION_FIRST

public static final int ACTION_FIRST
The first number in the range of ids used for action events.

ACTION_LAST

public static final int ACTION_LAST
The last number in the range of ids used for action events.

ACTION_PERFORMED

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

ActionEvent

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

getModifiers

public int getModifiers()
Returns the modifier keys held down during this action event.
Returns:
the integer sum 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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