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 {@code id} parameter
* of any particular {@code ActionEvent} instance is not
* in the range from {@code ACTION_FIRST} to {@code ACTION_LAST}.
*
* @see ActionListener
* @see Tutorial: How to Write an Action Listener
*
* @author Carl Quinn
* @since 1.1
*/
public class ActionEvent extends AWTEvent {
/**
* The shift modifier. An indicator that the shift key was held
* down during the event.
*/
public static final int SHIFT_MASK = Event.SHIFT_MASK;
/**
* The control modifier. An indicator that the control key was held
* down during the event.
*/
public static final int CTRL_MASK = Event.CTRL_MASK;
/**
* The meta modifier. An indicator that the meta key was held
* down during the event.
*/
public static final int META_MASK = Event.META_MASK;
/**
* The alt modifier. An indicator that the alt key was held
* down during the event.
*/
public static final int ALT_MASK = Event.ALT_MASK;
/**
* The first number in the range of ids used for action events.
*/
public static final int ACTION_FIRST = 1001;
/**
* The last number in the range of ids used for action events.
*/
public static final int ACTION_LAST = 1001;
/**
* This event id indicates that a meaningful action occured.
*/
public static final int ACTION_PERFORMED = ACTION_FIRST; //Event.ACTION_EVENT
/**
* The nonlocalized string that gives more details
* of what actually caused the event.
* This information is very specific to the component
* that fired it.
* @serial
* @see #getActionCommand
*/
String actionCommand;
/**
* 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.
*
* @serial
* @see #getWhen
*/
long when;
/**
* 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.
*
* @serial
* @see #getModifiers
*/
int modifiers;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -7671078796273832149L;
/**
* Constructs an ActionEvent object.
*
* 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.
* For information on allowable values, see
* the class description for {@link ActionEvent}
* @param command A string that may specify a command (possibly one
* of several) associated with the event
* @throws IllegalArgumentException if source is null
* @see #getSource()
* @see #getID()
* @see #getActionCommand()
*/
public ActionEvent(Object source, int id, String command) {
this(source, id, command, 0);
}
/**
* 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.
*
* @param source The object that originated the event
* @param id An integer that identifies the event.
* For information on allowable values, see
* the class description for {@link ActionEvent}
* @param command A string that may specify a command (possibly one
* of several) associated with the event
* @param 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 if source is null
* @see #getSource()
* @see #getID()
* @see #getActionCommand()
* @see #getModifiers()
*/
public ActionEvent(Object source, int id, String command, int modifiers) {
this(source, id, command, 0, 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.
*
* @param source The object that originated the event
* @param id An integer that identifies the event.
* For information on allowable values, see
* the class description for {@link ActionEvent}
* @param command A string that may specify a command (possibly one
* of several) associated with the event
* @param 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
* @param when A long that gives the time the event occurred.
* Passing negative or zero value
* is not recommended
* @throws IllegalArgumentException if source is null
* @see #getSource()
* @see #getID()
* @see #getActionCommand()
* @see #getModifiers()
* @see #getWhen()
*
* @since 1.4
*/
public ActionEvent(Object source, int id, String command, long when,
int modifiers) {
super(source, id);
this.actionCommand = command;
this.when = when;
this.modifiers = modifiers;
}
/**
* 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
*/
public String getActionCommand() {
return actionCommand;
}
/**
* 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
*/
public long getWhen() {
return when;
}
/**
* Returns the modifier keys held down during this action event.
*
* @return the bitwise-or of the modifier constants
*/
public int getModifiers() {
return modifiers;
}
/**
* 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
*/
public String paramString() {
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);
}
}