When I assign ringtone in android using code it won't paly it in a loop, why?

I use this code:

ContentValues values = new ContentValues();
values.put(ContactsContract.Data.CUSTOM_RINGTONE, Environment.get开发者_JS百科ExternalStorageDirectory().getPath() + "/ring.wav");
getContentResolver().update(ContactsContract.Contacts.CONTENT_URI, values , "DISPLAY_NAME = 'Ani'", null);

It works great but it play only one time. How do I make it to play in a loop?