Class: AppletTutorial
Okay, we've got our text-editing application running as a command line application. Let's take a look back to see how that worked, exactly.
public static void main(String argv[]) {
AppContext context = new ApplicationContext();
new ApplicationTutorial(context);
}
That application context that we created is actually a subclass of JFrame
and by passing it to the application's constructor, we got a command-line
application running in a JFrame. So, it seems perfectly logical to
expect that if we pass an applet context to the application, that we'll get
an "applet version" of our application. In fact this is exactly what we do.
public class AppletTutorial extends AppletContext {
public AppletTutorial() {
new ApplicationTutorial(this);
}
}
That was it! This tutorial would otherwise be a little boring, so let's take a closer look at the AppContext interface, since there are a few things that our simple application doesn't really make use of.
public interface AppContext extends RootPaneContainer {
public Action getExitAction();
public Image getIconImage ();
public JMenuBar getJMenuBar();
public String getTitle ();
public boolean isVisible();
public Component makeComponent();
public void setExitAction(Action exitAction);
public void setIconImage (Image image);
public void setJMenuBar(JMenuBar menu);
public void setSize(int w, int h);
public void setTitle (String title);
public void setVisible(boolean visible);
public void showStatus(String status);
}
The Title, Visible, JMenuBar and IconImage properties we've already used in our application. We've also made use of the fact that AppContext extends RootPaneContainer to add components to the context's content pane. The makeComponent method is useful for those things that require a Component to be passed in their constructor, such as modal dialogs. We know that the AppContext has to be a component, so a cast would be enough, but having a method is a bit more type-safe. The AbstractApplication class makes use of the showStatus method to display a string in the status bar.
An important part of this interface is that the context only has to implement those methods that make sense. ApplicationContext, for instance, ignores the showStatus() method and AppletContext ignores the setSize() method.