org.jdesktop.application

Class Application

java.lang.Object

org.jdesktop.application.AbstractBean

org.jdesktop.application.Application

Direct Known Subclasses:

SingleFrameApplication

@ProxyActions(value={"cut","copy","paste","delete"})
public abstract class Application
extends AbstractBean

The base class for Swing applications.

This class defines a simple lifecyle for Swing applications: initialize, startup, ready, and shutdown. The Application's startup method is responsible for creating the initial GUI and making it visible, and the shutdown method for hiding the GUI and performing any other cleanup actions before the application exits. The initialize method can be used configure system properties that must be set before the GUI is constructed and the ready method is for applications that want to do a little bit of extra work once the GUI is "ready" to use. Concrete subclasses must override the startup method.

Applications are started with the static launch method. Applications use the ApplicationContext getContext() to find resources, actions, local storage, and so on.

All Application subclasses must override startup and they should call exit() (which calls shutdown) to exit. Here's an example of a complete "Hello World" Application:

 public class MyApplication extends Application {
     JFrame mainFrame = null;
     @Override protected void startup() {
         mainFrame = new JFrame("Hello World");
         mainFrame.add(new JLabel("Hello World"));
         mainFrame.addWindowListener(new MainFrameListener());
         mainFrame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
         mainFrame.pack();
         mainFrame.setVisible(true);
     }
     @Override protected void shutdown() {
         mainFrame.setVisible(false);
     }
     private class MainFrameListener extends WindowAdapter {
         public void windowClosing(WindowEvent e) {
            exit();
         }
     }
     public static void main(String[] args) {
         Application.launch(MyApplication.class, args);
     }
 }
 

The mainFrame's defaultCloseOperation is set to DO_NOTHING_ON_CLOSE because we're handling attempts to close the window by calling ApplicationContext exit().

Simple single frame applications like the example can be defined more easily with the SingleFrameApplication Application subclass.

All of the Application's methods are called (must be called) on the EDT.

All but the most trivial applications should define a ResourceBundle in the resources subpackage with the same name as the application class (like resources/MyApplication.properties). This ResourceBundle contains resources shared by the entire application and should begin with the following the standard Application resources:

 Application.name = A short name, typically just a few words
 Application.id = Suitable for Application specific identifiers, like file names
 Application.title = A title suitable for dialogs and frames
 Application.version = A version string that can be incorporated into messages
 Application.vendor = A proper name, like Sun Microsystems, Inc.
 Application.vendorId = suitable for Application-vendor specific identifiers, like file names.
 Application.homepage = A URL like http://www.javadesktop.org
 Application.description =  One brief sentence
 Application.lookAndFeel = either system, default, or a LookAndFeel class name
 

The Application.lookAndFeel resource is used to initialize the UIManager lookAndFeel as follows:

• system - the system (native) look and feel
• default - use the JVM default, typically the cross platform look and feel
• nimbus - use the modern cross platform look and feel Nimbus
• a LookAndFeel class name - use the specified class

Author:

Hans Muller (Hans.Muller@Sun.COM)

See Also:

SingleFrameApplication, ApplicationContext, UIManager.setLookAndFeel(javax.swing.LookAndFeel)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Application.ExitListener Gives the Application a chance to veto an attempt to exit/quit.

Field Summary

Fields

Modifier and Type	Field and Description
static String	KEY_APPLICATION_ICON
static String	KEY_APPLICATION_TITLE
static String	KEY_APPLICATION_VENDOR_ID
protected boolean	ready

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Application() Not to be called directly, see launch.

Method Summary

Methods

Modifier and Type	Method and Description
void	addExitListener(Application.ExitListener listener) Adds an ExitListener to the list.
protected void	end() Called by exit to terminate the application.
void	exit() Gracefully shutdowns the application, calls exit(null) This version of exit() is convenient if the decision to exit the application wasn't triggered by an event.
void	exit(EventObject event) Gracefully shutdowns the application.
ApplicationContext	getContext() The ApplicationContext for this Application.
Application.ExitListener[]	getExitListeners() All of the ExitListeners added so far.
static Application	getInstance() The Application singleton.
static <T extends Application> T	getInstance(Class<T> applicationClass) The Application singleton.
boolean	handleQuit() Handles quit even on Mac Os X Developer should not use it directly
void	hide(View view) Hides the application View
protected void	initialize(String[] args) Responsible for initializations that must occur before the GUI is constructed by startup.
boolean	isReady() The state of the initial UI.
static <T extends Application> void	launch(Class<T> applicationClass, String[] args) Creates an instance of the specified Application subclass, sets the ApplicationContext application property, and then calls the new Application's initialize and startup methods.
void	quit(ActionEvent e) The default Action for quitting an application, quit just exits the application by calling exit(e).
protected void	ready() Called after the startup() method has returned and there are no more events on the system event queue.
void	removeExitListener(Application.ExitListener listener) Removes an ExitListener from the list.
void	show(View view) Shows the application View
protected void	shutdown() Called when the application exits.
protected abstract void	startup() Responsible for starting the application; for creating and showing the initial GUI.

Methods inherited from class org.jdesktop.application.AbstractBean

addPropertyChangeListener, addPropertyChangeListener, firePropertyChange, firePropertyChange, getPropertyChangeListeners, removePropertyChangeListener, removePropertyChangeListener

Methods inherited from class java.lang.Object

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

Field Detail

KEY_APPLICATION_TITLE

public static final String KEY_APPLICATION_TITLE

See Also:

Constant Field Values

KEY_APPLICATION_ICON

public static final String KEY_APPLICATION_ICON

See Also:

Constant Field Values

KEY_APPLICATION_VENDOR_ID

public static final String KEY_APPLICATION_VENDOR_ID

See Also:

Constant Field Values

ready

protected boolean ready

Constructor Detail

Application

protected Application()

Not to be called directly, see launch.

Subclasses can provide a no-args construtor to initialize private final state however GUI initialization, and anything else that might refer to public API, should be done in the startup method.

Method Detail

launch

public static <T extends Application> void launch(Class<T> applicationClass,
                                  String[] args)

Creates an instance of the specified Application subclass, sets the ApplicationContext application property, and then calls the new Application's initialize and startup methods. When UI is ready, method ready is called. The launch method is typically called from the Application's main:

     public static void main(String[] args) {
         Application.launch(MyApplication.class, args);
     }
 

The applicationClass constructor and startup methods run on the event dispatching thread.

Parameters:

applicationClass - the Application class to launch

args - main method arguments

See Also:

shutdown(), ApplicationContext.getApplication()

initialize

protected void initialize(String[] args)

Responsible for initializations that must occur before the GUI is constructed by startup.

This method is called by the static launch method, before startup is called. Subclasses that want to do any initialization work before startup must override it. The initialize method runs on the event dispatching thread.

By default initialize() does nothing.

Parameters:

args - the main method's arguments.

See Also:

launch(java.lang.Class<T>, java.lang.String[]), startup(), shutdown()

startup

protected abstract void startup()

Responsible for starting the application; for creating and showing the initial GUI.

This method is called by the static launch method, subclasses must override it. It runs on the event dispatching thread.

See Also:

launch(java.lang.Class<T>, java.lang.String[]), initialize(java.lang.String[]), shutdown()

ready

protected void ready()

Called after the startup() method has returned and there are no more events on the system event queue. When this method is called, the application's GUI is ready to use.

It's usually important for an application to start up as quickly as possible. Applications can override this method to do some additional start up work, after the GUI is up and ready to use.

See Also:

launch(java.lang.Class<T>, java.lang.String[]), startup(), shutdown()

shutdown

protected void shutdown()

Called when the application exits. Subclasses may override this method to do any cleanup tasks that are necessary before exiting. Obviously, you'll want to try and do as little as possible at this point. This method runs on the event dispatching thread.

See Also:

startup(), ready, exit(), addExitListener(org.jdesktop.application.Application.ExitListener)

exit

public final void exit()

Gracefully shutdowns the application, calls exit(null) This version of exit() is convenient if the decision to exit the application wasn't triggered by an event.

See Also:

exit(EventObject)

handleQuit

public boolean handleQuit()

Handles quit even on Mac Os X Developer should not use it directly

Returns:

always true

exit

public void exit(EventObject event)

Gracefully shutdowns the application.

If none of the ExitListener.canExit() methods return false, calls the ExitListener.willExit() methods, then shutdown(), and then exits the Application with end. Exceptions thrown while running willExit() or shutdown() are logged but otherwise ignored.

If the caller is responding to an GUI event, it's helpful to pass the event along so that ExitListeners' canExit methods that want to popup a dialog know on which screen to show the dialog. For example:

 class ConfirmExit implements Application.ExitListener {
     public boolean canExit(EventObject e) {
         Object source = (e != null) ? e.getSource() : null;
         Component owner = (source instanceof Component) ? (Component)source : null;
         int option = JOptionPane.showConfirmDialog(owner, "Really Exit?");
         return option == JOptionPane.YES_OPTION;
     }
     public void willExit(EventObejct e) {} 
 }
 myApplication.addExitListener(new ConfirmExit());
 

The eventObject argument may be null, e.g. if the exit call was triggered by non-GUI code, and canExit, willExit methods must guard against the possibility that the eventObject argument's source is not a Component.

Parameters:

event - the EventObject that triggered this call or null

See Also:

addExitListener(org.jdesktop.application.Application.ExitListener), removeExitListener(org.jdesktop.application.Application.ExitListener), shutdown(), end()

end

protected void end()

Called by exit to terminate the application. Calls Runtime.getRuntime().exit(0), which halts the JVM.

See Also:

exit()

addExitListener

public void addExitListener(Application.ExitListener listener)

Adds an ExitListener to the list.

Parameters:

listener - the ExitListener

See Also:

removeExitListener(org.jdesktop.application.Application.ExitListener), getExitListeners()

removeExitListener

public void removeExitListener(Application.ExitListener listener)

Removes an ExitListener from the list.

Parameters:

listener - the ExitListener

See Also:

addExitListener(org.jdesktop.application.Application.ExitListener), getExitListeners()

getExitListeners

public Application.ExitListener[] getExitListeners()

All of the ExitListeners added so far.

Returns:

all of the ExitListeners added so far.

quit

@Action
public void quit(ActionEvent e)

The default Action for quitting an application, quit just exits the application by calling exit(e).

Parameters:

e - the triggering event

See Also:

exit(EventObject)

getContext

public final ApplicationContext getContext()

The ApplicationContext for this Application.

Returns:

the Application's ApplicationContext

getInstance

public static <T extends Application> T getInstance(Class<T> applicationClass)

The Application singleton.

This method is only called after an Application has been launched.

Parameters:

applicationClass - this Application's subclass

Returns:

the launched Application singleton.

See Also:

launch(java.lang.Class<T>, java.lang.String[])

getInstance

public static Application getInstance()

The Application singleton.

This method is only called after an Application has been launched.

Returns:

the Application singleton or a placeholder

See Also:

launch(java.lang.Class<T>, java.lang.String[]), getInstance(Class)

show

public void show(View view)

Shows the application View

Parameters:

view - - View to show

See Also:

View

hide

public void hide(View view)

Hides the application View

Parameters:

view -

See Also:

View

isReady

public boolean isReady()

The state of the initial UI.

Returns:

true if the initial UI is ready