@CapDroid
Fixed working code from DArkO’s post:
ContentResolver cr = context.getContentResolver();
String[] PROJECTION = new String[] { ContactsContract.RawContacts._ID,
ContactsContract.Contacts.DISPLAY_NAME,
ContactsContract.Contacts.PHOTO_ID,
ContactsContract.CommonDataKinds.Email.DATA,
ContactsContract.CommonDataKinds.Photo.CONTACT_ID };
String order = "CASE WHEN "
+ ContactsContract.Contacts.DISPLAY_NAME
+ " NOT LIKE '%@%' THEN 1 ELSE 2 END, "
+ ContactsContract.Contacts.DISPLAY_NAME
+ ", "
+ ContactsContract.CommonDataKinds.Email.DATA
+ " COLLATE NOCASE";
String filter = ContactsContract.CommonDataKinds.Email.DATA + " NOT LIKE ''";
Cursor cur = cr.query(ContactsContract.CommonDataKinds.Email.CONTENT_URI, PROJECTION, filter, null, order);
Your cursor will have essential IDs as well as names and email addresses. The performance of this code is great because it requests few columns only.