Class DocumentExample

java.lang.Object
org.jdesktop.application.AbstractBean
org.jdesktop.application.Application
org.jdesktop.application.SingleFrameApplication
examples.DocumentExample
public class DocumentExample extends SingleFrameApplication
This is a very simple example of a SingleFrameApplication that loads and saves a single text document. Although it does not possess all of the usual trappings of a single-document app, like versioning or support for undo/redo, it does serve to highlight how to use actions, resources, and tasks.

The application's state is defined by two read-only bound properties:

File file
The current text File being edited.
boolean #isModified
True if the current file needs to be saved.
These properties are updated when the user interacts with the application. They can be used as binding sources, to monitor the application's state.

The application is launched in the main method on the "main" thread. All the work of actually constructing, intializing, and starting the application actually happens on the EDT.

The resources for this Application are defined in resources/DocumentExample.properties.

This application defines a small set of actions for opening and saving files: open, save, and saveAs. It inherits cut/copy/paste/delete ProxyActions from the Application class. The ProxyActions perform their action not on the component they're bound to (menu items and toolbar buttons), but on the component that currently has the keyboard focus. Their enabled state tracks the selection value of the component with the keyboard focus, as well as the contents of the system clipboard.

The action code that reads and writes files, runs asynchronously on background threads. The open, save, and saveAs actions all return a Task object which encapsulates the work that will be done on a background thread. The showAboutBox and closeAboutBox actions do their work synchronously.

Warning: this application is intended as a simple example, not as a robust text editor. Read it, don't use it.

See Also:

  • Constructor Details

    • DocumentExample

      public DocumentExample()

  • Method Details

    • getFile

      public File getFile()
      The File currently being edited. The default value of this property is "untitled.txt".

      This is a bound read-only property. It is never null.

      Returns:
      the value of the file property.
      See Also:

    • isModified

      public boolean isModified()
      True if the file value has been modified but not saved. The default value of this property is false.

      This is a bound read-only property.

      Returns:
      the value of the modified property.
      See Also:

    • open

      @Action public Task open()
      Prompt the user for a filename and then attempt to load the file.

      The file is loaded on a worker thread because we don't want to block the EDT while the file system is accessed. To do that, this Action method returns a new LoadFileTask instance, if the user confirms selection of a file. The task is executed when the "open" Action's actionPerformed method runs. The LoadFileTask is responsible for updating the GUI after it has successfully completed loading the file.

      Returns:
      a new LoadFileTask or null

    • save

      @Action(enabledProperty="modified") public Task save()
      Save the contents of the textArea to the current file.

      The text is written to the file on a worker thread because we don't want to block the EDT while the file system is accessed. To do that, this Action method returns a new SaveFileTask instance. The task is executed when the "save" Action's actionPerformed method runs. The SaveFileTask is responsible for updating the GUI after it has successfully completed saving the file.

      See Also:

    • saveAs

      @Action public Task saveAs()
      Save the contents of the textArea to the current file.

      This action is nearly identical to open. In this case, if the user chooses a file, a SaveFileTask is returned. Note that the selected file only becomes the value of the file property if the file is saved successfully.

    • showAboutBox

      @Action public void showAboutBox()
      Show the about box dialog.

    • closeAboutBox

      @Action public void closeAboutBox()
      Close the about box dialog.

    • initialize

      protected void initialize(String[] args)
      Description copied from class: Application
      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.

      Overrides:
      initialize in class Application
      Parameters:
      args - the main method's arguments.
      See Also:

    • startup

      protected void startup()
      Description copied from class: Application
      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.

      Specified by:
      startup in class Application
      See Also:

    • ready

      protected void ready()
      Description copied from class: Application
      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.

      Overrides:
      ready in class Application
      See Also:

    • main

      public static void main(String[] args)
      Launch the application on the EDT.
      See Also: