CSP for Java (JCSP) 1.0-rc4 API Specification: Class ActiveList

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CSP for Java
(JCSP) 1.0-rc4

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jcsp.awt
Class ActiveList

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.List
              |
              +--jcsp.awt.ActiveList

All Implemented Interfaces:: Accessible, CSProcess, ImageObserver, ItemSelectable, MenuContainer, Serializable

public class ActiveList
extends List
implements CSProcess

java.awt.List with a channel interface.

Process Diagram

                           ________________
                          |                |
                          |                | event
                          |                |----->-----
                          |                | (java.lang.String)
                          |                |
                          |                | itemEvent
                          |                |----->-----
                          |                | (java.awt.event.ItemEvent)
                          |                |
                          |                | componentEvent
                          |                |----->-----
                          |                | (java.awt.event.ComponentEvent)
                          |                |
                configure |                | focusEvent
               ----->-----|   ActiveList   |----->-----
       (java.lang.String) |                | (java.awt.event.FocusEvent)
      (java.lang.Integer) |                |
      (java.lang.Boolean) |                | keyEvent
   (ActiveList.Configure) |                |----->-----
                          |                | (java.awt.event.KeyEvent)
                          |                |
                          |                | mouseEvent
                          |                |----->-----
                          |                | (java.awt.event.MouseEvent)
                          |                |
                          |                | mouseMotionEvent
                          |                |----->-----
                          |                | (java.awt.event.MouseEvent)
                          |________________|

Description

ActiveList is a process extension of java.awt.List with channels for run-time configuration and event notification. The event channels should be connected to one or more application-specific server processes (instead of registering a passive object as a Listener to this component).

All channels are optional. The configure and event channels are settable from a constructor. When an item in the ActiveList is double-clicked, its label is written down the event channel. Other event channels can be added to notify the occurrence of any other events the component generates (by calling the appropriate addXXXEventChannel method before the process is run). Messages can be sent down the configure channel at any time to configure the component. See the table below for details.

All channels are managed by independent internal handler processes. It is, therefore, safe for a serial application process both to service an event channel and configure the component -- no deadlock can occur.

IMPORTANT: it is essential that event channels from this process are always serviced -- otherwise the Java Event Thread will be blocked and the GUI will stop responding. A simple way to guarantee this is to use channels configured with overwriting buffers. For example:

   final One2OneChannel myListEvent =
     One2OneChannel.create (new OverWriteOldestBuffer (n));
   final One2OneChannel myListItemEvent =
     One2OneChannel.create (new OverWriteOldestBuffer (n));
 
   final ActiveList myList = new ActiveList (null, myListEvent);
   myList.addItemEventChannel (myListItemEvent);

This will ensure that the Java Event Thread will never be blocked. Slow or inattentive readers may miss rapidly generated events, but the n most recent events will always be available.

Channel Protocols

Input Channels
configure	String	Empty strings are ignored. If the string is `"-*"`, all items in the list are removed. Otherwise, if the first character is `'-'`, the item corresponding to the tail of the string is removed from the list. Otherwise, the string is added to the end of the list.
	Integer	Sets the selected item in this `ActiveList` list to be the item at the specified position.
	Boolean	If this is the `Boolean.TRUE` object, the list is made active If this is the `Boolean.FALSE` object, the list is made inactive Other `Boolean` objects are ignored
	ActiveList.Configure	Invoke the user-defined `Configure.configure` method on the list.
Output Channels
event	String	When an item in the `ActiveList` is double-clicked, its label is written down this channel.
itemEvent	ItemEvent	See the `addItemEventChannel` method.
componentEvent	ComponentEvent	See the `addComponentEventChannel` method.
focusEvent	FocusEvent	See the `addFocusEventChannel` method.
keyEvent	KeyEvent	See the `addKeyEventChannel` method.
mouseEvent	MouseEvent	See the `addMouseEventChannel` method.
mouseMotionEvent	MouseEvent	See the `addMouseMotionEventChannel` method.

Example

 import java.awt.*;
 import java.awt.event.*;
 import jcsp.lang.*;
 import jcsp.util.*;
 import jcsp.awt.*;
 
 public class ActiveListExample {
 
   public static void main (String argv[]) {
 
     final Frame root = new Frame ("ActiveList Example");
 
     final Channel configure = new One2OneChannel ();
 
     final Channel event =
       One2OneChannel.create (new OverWriteOldestBuffer (10));
     final Channel itemEvent =
       One2OneChannel.create (new OverWriteOldestBuffer (10));
 
     final ActiveList list = new ActiveList (configure, event, 0, true);
     list.addItemEventChannel (itemEvent);
 
     final String[] menu = {"Hello World", "Rocket Science", "CSP",
                           "Monitors", "Ignore Me", "Goodbye World"};
 
     for (int i = 0; i < menu.length; i++) {
       list.add (menu[i]);
     }
 
     root.setSize (300, 105);
     root.add (list);
     root.setVisible (true);
 
     new Parallel (
       new CSProcess[] {           // respond to the event channel
         list,
         new CSProcess () {
           public void run () {
             boolean running = true;
             while (running) {
               final String s = (String) event.read ();
               System.out.println ("                         Action ==> `" + s + "'");
               running = (s != menu[menu.length - 1]);
             }
             root.setVisible (false);
             System.exit (0);
           }
         },
         new CSProcess () {        // respond to the itemEvent channel
           public void run () {
             while (true) {
               final ItemEvent e = (ItemEvent) itemEvent.read ();
               final Integer item = (Integer) e.getItem ();
               if (e.getStateChange () == ItemEvent.SELECTED) {
                 System.out.println ("Selected item " + item);
               } else {
                 System.out.println ("Unselected item " + item);
               }
             }
           }
         },
         new CSProcess () {        // dynamically reconfigure the list
           public void run () {
             CSTimer tim = new CSTimer ();
             long timeout = tim.read ();
             while (true) {
               timeout += 10000;
               tim.after (timeout);
               System.out.println ("*** Removing last three items ...");
               for (int i = 3; i < menu.length; i++) {
                 configure.write ("-" + menu[i]);
               }
               timeout += 10000;
               tim.after (timeout);
               System.out.println ("*** Restoring last three items ...");
               for (int i = 3; i < menu.length; i++) {
                 configure.write (menu[i]);
               }
             }
           }
         }
       }
     ).run ();
 
   }
 
 }

Author:: P.D.Austin and P.H.Welch
See Also:: List, ItemEvent, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form

Inner Class Summary

static interface ActiveList.Configure
          This enables general configuration of this component.

Inner classes inherited from class java.awt.List

List.AccessibleAWTList

Inner classes inherited from class java.awt.Component

Component.AccessibleAWTComponent

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

ActiveList()
          Constructs an ActiveList with no visible lines, no configuration or event channels and only one item selectable.

ActiveList(ChannelInput configure, ChannelOutput event)
          Constructs an ActiveList with configuration and event channels, but no visible items and only one item selectable.

ActiveList(ChannelInput configure, ChannelOutput event, int rows)
          Constructs an ActiveList with configuration and event channels, the specified number of visible lines and only one item selectable.

ActiveList(ChannelInput configure, ChannelOutput event, int rows, boolean multipleMode)
          Constructs an ActiveList with configuration and event channels, the specified number of visible lines and a multiple selection option.

ActiveList(int rows)
          Constructs an ActiveList with the specified number of visible lines, but with no configuration or event channels and only one item selectable.

ActiveList(int rows, boolean multipleMode)
          Constructs an ActiveList with the specified number of visible lines and a multiple selection option, but with no configuration or event channels.

Method Summary

void addComponentEventChannel(ChannelOutput componentEvent)
          Add a new channel to this component that will be used to notify that a ComponentEvent has occurred.

void addFocusEventChannel(ChannelOutput focusEvent)
          Add a new channel to this component that will be used to notify that a FocusEvent has occurred.

void addItemEventChannel(ChannelOutput itemEvent)
          Add a new channel to this component that will be used to notify that an ItemEvent has occurred.

void addKeyEventChannel(ChannelOutput keyEvent)
          Add a new channel to this component that will be used to notify that a KeyEvent has occurred.

void addMouseEventChannel(ChannelOutput mouseEvent)
          Add a new channel to this component that will be used to notify that a MouseEvent has occurred.

void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)
          Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred.

void run()
          The main body of this process.

void setConfigureChannel(ChannelInput configure)
          Sets the configuration channel for this ActiveList.

Methods inherited from class java.awt.List

add, add, addActionListener, addItem, addItem, addItemListener, addNotify, allowsMultipleSelections, clear, countItems, delItem, delItems, deselect, getAccessibleContext, getItem, getItemCount, getItems, getListeners, getMinimumSize, getMinimumSize, getPreferredSize, getPreferredSize, getRows, getSelectedIndex, getSelectedIndexes, getSelectedItem, getSelectedItems, getSelectedObjects, getVisibleIndex, isIndexSelected, isMultipleMode, isSelected, makeVisible, minimumSize, minimumSize, paramString, preferredSize, preferredSize, processActionEvent, processEvent, processItemEvent, remove, remove, removeActionListener, removeAll, removeItemListener, removeNotify, replaceItem, select, setMultipleMode, setMultipleSelections

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getName, getParent, getPeer, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ActiveList

public ActiveList()

Constructs an ActiveList with no visible lines, no configuration or event channels and only one item selectable.

ActiveList

public ActiveList(int rows)

Constructs an ActiveList with the specified number of visible lines, but with no configuration or event channels and only one item selectable.

Parameters:: rows - the number of visible lines.

ActiveList

public ActiveList(int rows,
                  boolean multipleMode)

Constructs an ActiveList with the specified number of visible lines and a multiple selection option, but with no configuration or event channels.

Parameters:: rows - the number of visible lines.; multipleMode - the multiple selection option.

ActiveList

public ActiveList(ChannelInput configure,
                  ChannelOutput event)

Constructs an ActiveList with configuration and event channels, but no visible items and only one item selectable.

Parameters:: configure - the channel for configuration events -- can be null if no configuration is required.; event - the String label from a list item will be output when it is double-clicked -- can be null if no notification is required.

ActiveList

public ActiveList(ChannelInput configure,
                  ChannelOutput event,
                  int rows)

Constructs an ActiveList with configuration and event channels, the specified number of visible lines and only one item selectable.

Parameters:: configure - the channel for configuration events -- can be null if no configuration is required.; event - the String label from a list item will be output when it is double-clicked -- can be null if no notification is required.; rows - the number of visible lines.

ActiveList

public ActiveList(ChannelInput configure,
                  ChannelOutput event,
                  int rows,
                  boolean multipleMode)

Constructs an ActiveList with configuration and event channels, the specified number of visible lines and a multiple selection option.

Parameters:: configure - the channel for configuration events -- can be null if no configuration is required.; event - the String label from a list item will be output when it is double-clicked -- can be null if no notification is required.; rows - the number of visible lines.; multipleMode - the multiple selection option.

Method Detail

setConfigureChannel

public void setConfigureChannel(ChannelInput configure)

Sets the configuration channel for this ActiveList. This method overwrites any configuration channel set in the constructor.

Parameters:: configure - the channel for configuration events -- can be null if no configuration is required.

addItemEventChannel

public void addItemEventChannel(ChannelOutput itemEvent)

Add a new channel to this component that will be used to notify that an ItemEvent has occurred. This should be used instead of registering a ItemListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.