android Null pointer issue in livewallpaper unsure of the cause

I'm writing a livewallpaper that will pull images from flickr and make them the background, and change every so often. Right now i've stubbed/ignored/circumvented the flickr part, and am ignoring the timed changes as well. Still i'm having the same null pointer error over and over and i can't figure out what's causing it.

here is the few methods related to the err开发者_如何学Cor

@Override
    public void onVisibilityChanged(boolean visible) {
        mVisible = visible;
        if (visible) {
            setImage(getPic());//***NULLPOINTERERROR
        } else {
            mHandler.removeCallbacks(getFlickrPic);
        }
    }

public void setImage(Bitmap bm)
    {
        final SurfaceHolder holder = getSurfaceHolder();
        Canvas c= null;
        try{
            c=holder.lockCanvas();
            if (c != null) {
                c.setBitmap(bm);
            }
        } finally { if (c != null) holder.unlockCanvasAndPost(c); }
    }

    public Bitmap getPic()
    {
        Bitmap bm = null;

        bm = ((BitmapDrawable) LoadImageFromWebOperations("http://farm6.static.flickr.com/5102/5655314644_b7038a5438_z.jpg")).getBitmap();
        while (bm==null)
        {bm = ((BitmapDrawable) getResources().getDrawable(R.drawable.no)).getBitmap();}

        return bm;
        }

    private Drawable LoadImageFromWebOperations(String url)
           {
                try
                {
                    InputStream is = (InputStream) new URL(url).openStream();
                    Drawable d = Drawable.createFromStream(is, "src name");
                    return d;
                }catch (Exception e) {
                    System.out.println("Exc="+e);
                    return null;
                }
            }

I keep getting a NullPointerException for method getPic() in the OnVisibilityChanged(visible) method, noted with the *comment.

If any more information is necessary please ask. like i said i don't know why it's giving me this error so there's a possibility it's something from code i haven't included. thanks!

Wow thats that for a construct?

while (bm==null) {
    bm = ((BitmapDrawable) getResources().getDrawable(R.drawable.no)).getBitmap();
}

That looks evil...

Anyway, your issue is the following line:

bm = ((BitmapDrawable) LoadImageFromWebOperations("http://farm6.static.flickr.com/5102/5655314644_b7038a5438_z.jpg")).getBitmap()

LoadImageFromWebOperations can return null. In that case you still call getBitmap() on a null reference...

LoadImageFromWebOperations returns null if an error occures. in getPic you try to call getBitmap() on the return value of LoadImageFromWebOperations - if the value returned is null you are trying to call getBitmap() on a null-object, which will cause your NPE