jcsp.awt
Class ActiveMenu
java.lang.Object
|
+--java.awt.MenuComponent
|
+--java.awt.MenuItem
|
+--java.awt.Menu
|
+--jcsp.awt.ActiveMenu
- All Implemented Interfaces:
- Accessible, CSProcess, MenuContainer, Serializable
- public class ActiveMenu
- extends Menu
- implements CSProcess
java.awt.Menu
with a channel interface.
Process Diagram
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configure
| | event
----->-----| ActiveMenu |----->-----
(java.lang.String) | | (java.lang.String)
(java.awt.MenuShortcut) | |
(java.lang.Integer) | |
(java.lang.Boolean) | |
(ActiveMenu.Configure
) | |
| |
|__________________|
Description
ActiveMenu is a process extension of java.awt.Menu
with channels for run-time configuration and event notification. The event channel
should be connected to an application-specific server process (instead
of registering a passive object as a Listener to this component).
The configure and event channels are
settable from a constructor.
The event channel delivers the command string associated with this
ActiveMenu whenever it is selected.
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 the event channel and configure
the component -- no deadlock can occur.
IMPORTANT: it is essential that a (non-null) event channel from this process is
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 myMenuEvent =
One2OneChannel.create (new OverWriteOldestBuffer (n));
final ActiveMenu myMenu =
new ActiveMenu (null, myMenuEvent, "Look at this");
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.
Input Channels |
configure |
String |
Change the label on the ActiveMenu to the value of the String |
java.awt.MenuShortcut |
Sets the MenuShortcut for the ActiveMenu |
Integer |
Inserts a separator at the specified position.
|
Boolean |
- If this is the Boolean.TRUE object,
the menu is made active
- If this is the Boolean.FALSE object,
the menu is made inactive
- Other Boolean objects are ignored
|
ActiveMenu.Configure |
Invoke the user-defined Configure.configure method on the activeMenu. |
Output Channels |
event |
String |
The command for the ActiveMenu (when the menu is selected) |
Example
import java.awt.*;
import java.awt.event.*;
import jcsp.lang.*;
import jcsp.util.*;
import jcsp.awt.*;
public class ActiveMenuExample {
public static void main (String argv[]) {
final ActiveClosingFrame activeClosingFrame =
new ActiveClosingFrame ("ActiveCheckboxMenuItem Example");
final ActiveFrame frame = activeClosingFrame.getActiveFrame ();
final MenuBar menuBar = new MenuBar ();
frame.setMenuBar (menuBar);
final Menu fileMenu = new Menu ("File");
menuBar.add (fileMenu);
final String[] fileOptions = {"Hello World", "Rocket Science", "CSP",
"Monitors", "Ignore Me", "Goodbye World"};
final Channel event[] =
Any2OneChannel.create (2, new OverWriteOldestBuffer (10));
final ActiveMenuItem[] fileMenuItem =
new ActiveMenuItem[fileOptions.length];
for (int i = 0; i < fileOptions.length; i++) {
fileMenuItem[i] = new ActiveMenuItem (null, event[0], fileOptions[i]);
fileMenu.add (fileMenuItem[i]);
}
fileMenu.addSeparator ();
final Any2OneChannel langConfigure = new Any2OneChannel ();
final ActiveMenu langMenu = new ActiveMenu (langConfigure, null, "Language");
fileMenu.add (langMenu); // set up the active langMenu as a sub-menu
final String[] langOptions = {"occam", "Java", "Smalltalk", "Algol-60",
"Pascal", "Haskell", "SML", "Lisp"};
final ActiveCheckboxMenuItem[] langCheckboxMenuItem =
new ActiveCheckboxMenuItem[langOptions.length];
for (int i = 0; i < langOptions.length; i++) {
langCheckboxMenuItem[i] =
new ActiveCheckboxMenuItem (null, event[1], langOptions[i]);
langMenu.add (langCheckboxMenuItem[i]);
}
frame.setSize (700, 350);
frame.setBackground (Color.green);
frame.setVisible (true);
new Parallel (
new CSProcess[] { // don't forget to include all active processes
langMenu,
activeClosingFrame,
new Parallel (fileMenuItem),
new Parallel (langCheckboxMenuItem),
new CSProcess () {
public void run () {
boolean running = true;
while (running) {
final String s = (String) event[0].read ();
System.out.println ("File ==> `" + s + "' selected ...");
if (s == fileOptions[0]) {
langConfigure.write (Boolean.TRUE);
System.out.println ("`Language' enabled ...");
}
running = (s != fileOptions[fileOptions.length - 1]);
}
frame.setVisible (false);
System.exit (0);
}
},
new CSProcess () {
public void run () {
while (true) {
final ItemEvent e = (ItemEvent) event[1].read ();
final String item = (String) e.getItem ();
System.out.print ("Language ==> `" + item);
if (e.getStateChange () == ItemEvent.SELECTED) {
System.out.println ("' selected ...");
if (item == langOptions[0]) {
langConfigure.write (Boolean.FALSE);
System.out.println ("`Language' disabled ...");
}
} else {
System.out.println ("' deselected ...");
}
}
}
}
}
).run ();
}
}
- Author:
- P.D.Austin and P.H.Welch
- See Also:
Menu
,
ItemEvent
,
ComponentEvent
,
FocusEvent
,
KeyEvent
,
MouseEvent
,
OverWriteOldestBuffer
, Serialized Form
Inner Class Summary |
static interface |
ActiveMenu.Configure
This enables general configuration of this component. |
Constructor Summary |
ActiveMenu()
Constructs an ActiveMenu with no initial label and no configuration
or event channels. |
ActiveMenu(ChannelInput configure,
ChannelOutput event)
Constructs an ActiveMenu with configuration and event channels,
but with no initial label. |
ActiveMenu(ChannelInput configure,
ChannelOutput event,
String label)
Constructs an ActiveMenu with configuration and event channels
and an initial label. |
ActiveMenu(ChannelInput configure,
ChannelOutput event,
String label,
boolean tearOff)
Constructs an ActiveMenu with configuration and event channels,
an initial label and a tear-off option. |
ActiveMenu(String label)
Constructs an ActiveMenu with an initial label,
but with no configuration or event channels. |
ActiveMenu(String label,
boolean tearOff)
Constructs an ActiveMenu with an initial label
and a tear-off option, but with no configuration
or event channels. |
Methods inherited from class java.awt.Menu |
add, add, addNotify, addSeparator, countItems, getAccessibleContext, getItem, getItemCount, insert, insert, insertSeparator, isTearOff, paramString, remove, remove, removeAll, removeNotify |
Methods inherited from class java.awt.MenuItem |
addActionListener, deleteShortcut, disable, disableEvents, enable, enable, enableEvents, getActionCommand, getLabel, getListeners, getShortcut, isEnabled, processActionEvent, processEvent, removeActionListener, setActionCommand, setEnabled, setLabel, setShortcut |
ActiveMenu
public ActiveMenu()
- Constructs an ActiveMenu with no initial label and no configuration
or event channels.
ActiveMenu
public ActiveMenu(String label)
- Constructs an ActiveMenu with an initial label,
but with no configuration or event channels.
- Parameters:
label
- the label on the menu.
ActiveMenu
public ActiveMenu(String label,
boolean tearOff)
- Constructs an ActiveMenu with an initial label
and a tear-off option, but with no configuration
or event channels.
- Parameters:
label
- the label on the menu.tearOff
- if true, this is a tear-off menu.
ActiveMenu
public ActiveMenu(ChannelInput configure,
ChannelOutput event)
- Constructs an ActiveMenu with configuration and event channels,
but with no initial label.
- Parameters:
configure
- the channel for configuration events
-- can be null if no configuration is required.
ActiveMenu
public ActiveMenu(ChannelInput configure,
ChannelOutput event,
String label)
- Constructs an ActiveMenu with configuration and event channels
and an initial label.
- Parameters:
configure
- the channel for configuration events
-- can be null if no configuration is required.label
- the label on the menu.
ActiveMenu
public ActiveMenu(ChannelInput configure,
ChannelOutput event,
String label,
boolean tearOff)
- Constructs an ActiveMenu with configuration and event channels,
an initial label and a tear-off option.
- Parameters:
configure
- the channel for configuration events
-- can be null if no configuration is required.label
- the label on the menu.tearOff
- if true, this is a tear-off menu.
setConfigureChannel
public void setConfigureChannel(ChannelInput configure)
- Sets the configuration channel for this ActiveMenu.
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.
run
public void run()
- The main body of this process.
- Specified by:
run
in interface CSProcess
Submit a bug or feature to jcsp-team@ukc.ac.uk
Version 1.0-rc4 of the JCSP API Specification (Copyright 1997-2000 P.D.Austin and P.H.Welch - All Rights Reserved)
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.