In my app, user writes a phone number, and I want to find the contact name with that phone number?
I usually search the contacts like this:
Cursor
You should have a look at the recommended ContactsContract.PhoneLookup provider
A table that represents the result of looking up a phone number, for example for caller ID. To perform a lookup you must append the number you want to find to CONTENT_FILTER_URI. This query is highly optimized.
Uri uri = Uri.withAppendedPath(PhoneLookup.CONTENT_FILTER_URI, Uri.encode(phoneNumber));
resolver.query(uri, new String[]{PhoneLookup.DISPLAY_NAME,...