org.jcsp.awt
Class ActiveList

java.lang.Object
  java.awt.Component
      java.awt.List
          org.jcsp.awt.ActiveList

All Implemented Interfaces:

ImageObserver, ItemSelectable, MenuContainer, Serializable, Accessible, CSProcess

public class ActiveList
extends List
implements CSProcess

java.awt.List with a channel interface.

Process Diagram

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 = Channel.one2one (new OverWriteOldestBuffer (n));
   final One2OneChannel myListItemEvent = Channel.one2one (new OverWriteOldestBuffer (n));
 
   final ActiveList myList = new ActiveList (null, myListEvent.out ());
   myList.addItemEventChannel (myListItemEvent.out ());
 

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 org.jcsp.lang.*;
 import org.jcsp.util.*;
 import org.jcsp.awt.*;
 
 public class ActiveListExample {
 
   public static void main (String argv[]) {
 
     final Frame root = new Frame ("ActiveList Example");
 
     final One2OneChannel configure = Channel.one2one ();
 
     final One2OneChannel event = Channel.one2one (new OverWriteOldestBuffer (10));
     final One2OneChannel itemEvent = Channel.one2one (new OverWriteOldestBuffer (10));
 
     final ActiveList list = new ActiveList (configure.in (), event.out (), 0, true);
     list.addItemEventChannel (itemEvent.out ());
 
     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.in ().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.in ().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.out ().write ("-" + menu[i]);
               }
               timeout += 10000;
               tim.after (timeout);
               System.out.println ("*** Restoring last three items ...");
               for (int i = 3; i < menu.length; i++) {
                 configure.out ().write (menu[i]);
               }
             }
           }
         }
       }
     ).run ();
 
   }
 
 }
 

Author:

P.D. Austin and P.H. Welch

See Also:

List, ItemEvent, ComponentEvent, FocusEvent, KeyEvent, MouseEvent, OverWriteOldestBuffer, Serialized Form

Nested Class Summary

static interface

ActiveList.Configure This enables general configuration of this component.

Nested classes/interfaces inherited from class java.awt.List

List.AccessibleAWTList

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary

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, getActionListeners, getItem, getItemCount, getItemListeners, 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, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, 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, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, 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.

NOTE: This method must be called before this process is run.

Parameters:

itemEvent - the channel down which to send ItemEvents.

addComponentEventChannel

public void addComponentEventChannel(ChannelOutput componentEvent)

Add a new channel to this component that will be used to notify that a ComponentEvent has occurred. This should be used instead of registering a ComponentListener 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.

NOTE: This method must be called before this process is run.

Parameters:

componentEvent - the channel down which to send ComponentEvents.

addFocusEventChannel

public void addFocusEventChannel(ChannelOutput focusEvent)

Add a new channel to this component that will be used to notify that a FocusEvent has occurred. This should be used instead of registering a FocusListener 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.

NOTE: This method must be called before this process is run.

Parameters:

focusEvent - the channel down which to send FocusEvents.

addKeyEventChannel

public void addKeyEventChannel(ChannelOutput keyEvent)

Add a new channel to this component that will be used to notify that a KeyEvent has occurred. This should be used instead of registering a KeyListener 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.

NOTE: This method must be called before this process is run.

Parameters:

keyEvent - the channel down which to send KeyEvents.

addMouseEventChannel

public void addMouseEventChannel(ChannelOutput mouseEvent)

Add a new channel to this component that will be used to notify that a MouseEvent has occurred. This should be used instead of registering a MouseListener 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.

NOTE: This method must be called before this process is run.

Parameters:

mouseEvent - the channel down which to send MouseEvents.

addMouseMotionEventChannel

public void addMouseMotionEventChannel(ChannelOutput mouseMotionEvent)

Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred. This should be used instead of registering a MouseMotionListener 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.

NOTE: This method must be called before this process is run.

Parameters:

mouseMotionEvent - the channel down which to send MouseMotionEvents.

run

public void run()

The main body of this process.

Specified by:

run in interface CSProcess