java.awt.event

Class ActionEvent

Contents
  • 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 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.

        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 for ActionEvent
        command - A string that may specify a command (possibly one of several) associated with the event
        Throws:
        IllegalArgumentException - if source 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 for ActionEvent
        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 - if source 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 for ActionEvent
        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 - if source 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 class AWTEvent
        Returns:
        a string identifying the event and its associated command

Document created the 11/06/2005, last modified the 04/03/2020
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