Understanding architecture of Android contacts

Question

I am developing an Android app which needs to know when a contact is added/updated/deleted.

So I read several posts for it. I understand that we can get notified through

Answer 1

I think the best practice is to monitoring whenever a contact has aggregate to another one and identify them by the contactName, not the _ID or CONTACT_ID. Take a look at this possibly contacts operations:

Insert

A Contact cannot be created explicitly. When a raw contact is inserted, the provider will first try to find a Contact representing the same person. If one is found, the raw contact's CONTACT_ID column gets the _ID of the aggregate Contact. If no match is found, the provider automatically inserts a new Contact and puts its _ID into the CONTACT_ID column of the newly inserted raw contact.

Update

Only certain columns of Contact are modifiable: TIMES_CONTACTED, LAST_TIME_CONTACTED, STARRED, CUSTOM_RINGTONE, SEND_TO_VOICEMAIL. Changing any of these columns on the Contact also changes them on all constituent raw contacts.

Delete

Be careful with deleting Contacts! Deleting an aggregate contact deletes all constituent raw contacts. The corresponding sync adapters will notice the deletions of their respective raw contacts and remove them from their back end storage.

Query

If you need to read an individual contact, consider using CONTENT_LOOKUP_URI instead of CONTENT_URI. If you need to look up a contact by the phone number, use PhoneLookup.CONTENT_FILTER_URI, which is optimized for this purpose. If you need to look up a contact by partial name, e.g. to produce filter-as-you-type suggestions, use the CONTENT_FILTER_URI URI. If you need to look up a contact by some data element like email address, nickname, etc, use a query against the ContactsContract.Data table. The result will contain contact ID, name etc.

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The problem, though, is that you could have two 'Phillip Morris' in your contact list that aren't the same person.

For further information, see this section of Android Classes Documentation.