Android hourglass

You can use a ProgressDialog:

ProgressDialog dialog = new ProgressDialog(this);
dialog.setMessage("Thinking...");
dialog.setIndeterminate(true);
dialog.setCancelable(false);
dialog.show();

The above code will show the following dialog on top of your Activity:

Alternatively (or additionally) you can display a Progress indicator in the title bar of your Activity.

You need to request this as a feature near the top of the onCreate() method of your Activity using the following code:

requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);

Then turn it on like this:

setProgressBarIndeterminateVisibility(true);

and turn it off like this:

setProgressBarIndeterminateVisibility(false);