Class Application

java.lang.Object
org.jdesktop.application.AbstractBean
org.jdesktop.application.Application
Direct Known Subclasses:
ActionExample1, ActionExample2, ActionExample3, ActionExample4, ApplicationExample1, ApplicationExample2, ExitExample1, LocalStorageExample1, SessionStorageExample1, SingleFrameApplication
@ProxyActions({"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 singleton 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
  • a LookAndFeel class name - use the specified class
See Also:

  • Constructor Details

    • 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 Details

    • 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 startup method. 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:

    • 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:

    • 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:

    • 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:

    • shutdown

      protected void shutdown()
      Called when the application exits. Subclasses may override this method to do any cleanup tasks that are neccessary 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:

    • exit

      public final void exit()
      Gracefully shutdown 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

      public void exit(EventObject event)
      Gracefully shutdown 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:

    • end

      protected void end()
      Called by exit to terminate the application. Calls Runtime.getRuntime().exit(0), which halts the JVM.
      See Also:

    • addExitListener

      public void addExitListener(Application.ExitListener listener)
      Add an ExitListener to the list.
      Parameters:
      listener - the ExitListener
      See Also:

    • removeExitListener

      public void removeExitListener(Application.ExitListener listener)
      Remove an ExitListener from the list.
      Parameters:
      listener - the ExitListener
      See Also:

    • 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:

    • getContext

      public final ApplicationContext getContext()
      The ApplicationContext singleton for this Application.
      Returns:
      the Application's ApplicationContext singleton

    • getInstance

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

      Typically this method is only called after an Application has been launched however in some situations, like tests, it's useful to be able to get an Application object without actually launching. In that case, an instance of the specified class is constructed and configured as it would be by the launch method. However it's initialize and startup methods are not run.

      Parameters:
      applicationClass - this Application's subclass
      Returns:
      the launched Application singleton.
      See Also:

    • getInstance

      public static Application getInstance()
      The Application singleton, or a placeholder if launch hasn't been called yet.

      Typically this method is only called after an Application has been launched however in some situations, like tests, it's useful to be able to get an Application object without actually launching. The placeholder Application object provides access to an ApplicationContext singleton and has the same semantics as launching an Application defined like this: 

      public class PlaceholderApplication extends Application {
    public void startup() { }
}
Application.launch(PlaceholderApplication.class);
      Returns:
      the Application singleton or a placeholder
      See Also:

    • show

      public void show(View view)

    • hide

      public void hide(View view)