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ActionEvent.javaAPI DocJava SE 5 API8436Fri Aug 26 14:56:48 BST 2005java.awt.event

ActionEvent

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 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".

see
ActionListener
see
Tutorial: Java 1.1 Event Model
see
Reference: The Java Class Libraries (update file)
author
Carl Quinn
version
1.29 01/28/04
since
1.1

Fields Summary
public static final int
SHIFT_MASK
The shift modifier. An indicator that the shift key was held down during the event.
public static final int
CTRL_MASK
The control modifier. An indicator that the control key was held down during the event.
public static final int
META_MASK
The meta modifier. An indicator that the meta key was held down during the event.
public static final int
ALT_MASK
The alt modifier. An indicator that the alt key was held down during the event.
public static final int
ACTION_FIRST
The first number in the range of ids used for action events.
public static final int
ACTION_LAST
The last number in the range of ids used for action events.
public static final int
ACTION_PERFORMED
This event id indicates that a meaningful action occured.
String
actionCommand
The nonlocalized string that gives more details of what actually caused the event. This information is very specific to the component that fired it.
long
when
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.
int
modifiers
This represents the key modifier that was selected, and is used to determine the state of the selected key. If no modifier has been selected it will default to zero.
private static final long
serialVersionUID
Constructors Summary
public ActionEvent(Object source, int id, String command)
Constructs an ActionEvent object.

Note that passing in an invalid id results in unspecified behavior. This method throws an IllegalArgumentException if source is null. A null command string is legal, but not recommended.

param
source the object that originated the event
param
id an integer that identifies the event
param
command a string that may specify a command (possibly one of several) associated with the event
throws
IllegalArgumentException if source is null


                                                                                                        
           
        this(source, id, command, 0);
    
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. This method throws an IllegalArgumentException if source is null. A null command string is legal, but not recommended.

param
source the object that originated the event
param
id an integer that identifies the event
param
command a string that may specify a command (possibly one of several) associated with the event
param
modifiers the modifier keys held down during this action
throws
IllegalArgumentException if source is null

        this(source, id, command, 0, modifiers);
    
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. This method throws an IllegalArgumentException if source is null. A null command string is legal, but not recommended.

param
source the object that originated the event
param
id an integer that identifies the event
param
command a string that may specify a command (possibly one of several) associated with the event
param
when the time the event occurred
param
modifiers the modifier keys held down during this action
throws
IllegalArgumentException if source is null
since
1.4

        super(source, id);
        this.actionCommand = command;
        this.when = when;
        this.modifiers = modifiers;
    
Methods Summary
public java.lang.StringgetActionCommand()
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.

return
the string identifying the command for this event

        return actionCommand;
    
public intgetModifiers()
Returns the modifier keys held down during this action event.

return
the bitwise-or of the modifier constants

        return modifiers;
    
public longgetWhen()
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.

return
this event's timestamp
since
1.4

        return when;
    
public java.lang.StringparamString()
Returns a parameter string identifying this action event. This method is useful for event-logging and for debugging.

return
a string identifying the event and its associated command

        String typeStr;
        switch(id) {
          case ACTION_PERFORMED:
              typeStr = "ACTION_PERFORMED";
              break;
          default:
              typeStr = "unknown type";
        }
        return typeStr + ",cmd="+actionCommand+",when="+when+",modifiers="+
            KeyEvent.getKeyModifiersText(modifiers);