Android :: Displaying Image From ByteArray

I have a Main class with has onCreate() method. in that method i have made the MapFile class' object.and called its readFile() and readIndex() methods. in readIndex() method i call another class named MapTile where i read the images tiles from my binary file and there i have to display my image.now question is how can i display image without putting my code into onCreate(Bundle savedInstanceStare) method.i am trying this way but on first line it gives me null pointer exception.

ImageView image = (ImageView) findViewById(android.R.id.icon); Bitmap bMap = BitmapFactory.decodeByteArray(imageTile, 0, imageTile.length);image.setImageBitmap(bMap);