My site uses Twenty Fourteen theme. But the theme is very narrow.
Actually, the loading images from URL to ImageView (ImageView itself is in GridView or ListView) is not a simple task. You should provide memory and disk caching to avoid reload image again and again.
The simpliest way to show progress in ActionBar is
super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); setContentView(R.layout.activity_main);