Question

I am calling this class which is PopupScreen.

public class Custom_LoadingScreen extends PopupScreen {
private VerticalFieldManager vfm;
private Util_AnimateGifField anmtFldCycle = null;
private GIFEncodedImage gifImgCycle;

public Custom_LoadingScreen() {
    super(new VerticalFieldManager());
    Background bg = BackgroundFactory.createSolidTransparentBackground(
            Color.BLACK, 190);
    setBackground(bg);
    setBorder(BorderFactory.createSimpleBorder(new XYEdges(),
            Border.STYLE_TRANSPARENT));

    gifImgCycle = (GIFEncodedImage) GIFEncodedImage
            .getEncodedImageResource("LoadingSpinner.gif");
    anmtFldCycle = new Util_AnimateGifField(gifImgCycle,
            Field.FIELD_HCENTER);

    vfm = new VerticalFieldManager(USE_ALL_WIDTH) {
        protected void sublayout(int maxWidth, int maxHeight) {
            super.sublayout(Display.getWidth(), Display.getHeight());
            setExtent(Display.getWidth(), Display.getHeight());
        }
    };
    int padding = (Display.getHeight() - 16) / 2;
    if (padding > 0) {
        anmtFldCycle.setPadding(padding, 0, 0, 0);
    }
    vfm.add(anmtFldCycle);
    add(vfm);
}

//public void Popupscreen() {
    //Main.getUiApplication().popScreen(this);
//}

public boolean keyDown(int keycode, int status) {
    if (Keypad.key(keycode) == Keypad.KEY_ESCAPE) {
        Main.getUiApplication().popScreen(this);
        return true;
    }
    return super.keyDown(keycode, status);
}
}

In a button, I pushed it before goes to next screen.

financebtn = new Custom_ButtonField(finance, financeactive,
            financeactive) {
        protected boolean navigationClick(int status, int time) {
            Main.getUiApplication().pushScreen(new Custom_LoadingScreen());
            Main.getUiApplication().invokeLater(new Runnable() {
                public void run() {
                //  Main.getUiApplication().popScreen();
                    Main.getUiApplication().pushScreen(
                            new Main_NewsDetail());
                }

            }, 1 * 1000, false);

            return true;
        }
    };
    add(financebtn);

The result give me Uncaught:ClassCastException. I can call another class which is similar to custom_loadingscreen also popupscreen. It work fine.

I also tried call this class in another button yet still same problem.

Answer 1

If you take a look at your Custom_LoadingScreen code, there’s only one place where you are doing a cast:

gifImgCycle = (GIFEncodedImage) GIFEncodedImage
        .getEncodedImageResource("LoadingSpinner.gif");

So, that’s a good place to start looking. If you Google for “BlackBerry GIFEncodedImage ClassCastException”, you’ll find this thread:

http://supportforums.blackberry.com/t5/Java-Development/GIFEncodedImage-in-BlackBerry-OS7/td-p/1228959

The problem is that, for optimization, BlackBerry likes to convert images to the PNG format, which most smartphones work best with. So, what’s happening here is that your GIF image is actually being converted to a PNG image. Therefore, when you call the getEncodedImageResource() method, the object you are getting back may actually be of type PNGEncodedImage, not GIFEncodedImage, and you get the exception. Sneaky, huh?

You can solve it a few ways.

1. In the Blackberry_App_Descriptor.xml file, you can uncheck the setting that specifies that images are converted to PNG (Build tab -> Convert image files to png)
2. You can trick the build system by renaming your GIF file to something like LoadingSpinner.agif. The toolset doesn’t recognize the .agif extension, and therefore won’t try to convert it. If you do this, of course, remember to change the filename in your Java code, too, when loading it.
3. You can change the code to use PNGEncodedImage, or test the object like this:

EncodedImage img = EncodedImage.getEncodedImageResource("LoadingSpinner.gif");
if (img instanceof GIFEncodedImage) {
   // cast to GIFEncodedImage
} else if (img instanceof PNGEncodedImage) {
   // cast to PNGEncodedImage
}

Number (1) will lose the non-PNG to PNG conversion optimization for all your non-PNG images, not just this one.

Number (2) does look a little ugly. The benefit of doing this, though, is that you can disable this behaviour for just this one image. If most of your images are not PNG images, it might be valuable to let BlackBerry optimize for you, for the other images. But, maybe this one needs to be a GIF. So, #2 lets you handle this one as a special case.

I’m just guessing that this image might be an animated GIF? Is that right? If so, you probably want to keep it as a GIF, so you won’t want to do number (3), which lets it be converted to a PNG, and uses it as such.