set header and footer in BlackBerry in VerticalFieldManager

问题

I searched how to set header and footer in BlackBerry and I found the functions setTitle() and setStatus().

My problem is I have created a class that extends VerticalFieldManager. In VerticalFieldManager, it is not showing me setStatus function as this is function of MainScreen class.

回答1:

You're right. A VerticalFieldManager does not allow you to setStatus() directly.

It's important to understand the relationship between the classes in the BlackBerry UI framework.

First of all, there are Screen classes. Normally, a Screen will take up the entire device screen. You can have many different Screen classes in your app. Maybe one Screen for a splash image, one screen for a map view, one screen for settings, etc.

Inside your screens, you will often have Manager classes. A VerticalFieldManager is a kind of Manager that arranges its contents top-to-bottom, in the order that you add them. A Manager holds a group of related objects, but it does not have to span the full screen height, or width.

Inside your managers, you will usually have multiple Field objects. A Field is the individual item in the heirarchy. ButtonField, EditField, or BrowserField are all kinds of fields. They will usually be added to managers (containers). Those managers will then usually be added to screens.

So, in your case, I think what you should have is a screen class. In that screen class, you will set the header and footer by calling setTitle() and setStatus(). The content between the header and footer will all be contained in a VerticalFieldManager that you add to the screen. Something like this:

public class MyScreen extends MainScreen {

   public MyScreen() {
      super(MainScreen.VERTICAL_SCROLL | MainScreen.VERTICAL_SCROLLBAR);

      // set a header for this screen
      setTitle("My Header / Title");

      // screen contents go in the vertical field manager

      // NOTE:  you can replace VerticalFieldManager with your own class
      //   that extends Manager, or VerticalFieldManager, if you like
      VerticalFieldManager vfm = new VerticalFieldManager();
      vfm.add(new LabelField("One"));
      vfm.add(new ButtonField("Two", ButtonField.CONSUME_CLICK));
      vfm.add(new CheckboxField("Three", true));

      add(vfm);

      // use a bitmap as a footer
      Bitmap footer = Bitmap.getBitmapResource("footer.png");
      setStatus(new BitmapField(footer));
   }
}

来源：https://stackoverflow.com/questions/15127766/set-header-and-footer-in-blackberry-in-verticalfieldmanager

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