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how to display device address book ordered by custom external data

In my android application I would like to display the mobile user's contacts (names, profile picture ) displaying first the contacts that have already installed and registrered that application (the matching is made by contact's email).
Trying to loop over each contact and match if their email is already registered (in an external SQLITE table) don't seems to be an efficient way.
I would like to directly add (somewhere in the address book ?) the extra data "isRegistered = true/false) and order my addreess book query by this value to scroll the address book.
Is it possible? How to implement this in detail ?

OPTION 1
I think the most efficient way would be what you thought about initially, with a slight improvement:
store the list of registered emails (for the user's contacts) in a local SQLite DB.
read the entire list of emails on application launch, and store them in a HashSet
When sorting the contacts, create a custom Comparator to first check if the contact is an app user or not, and only then fallback to name compare.
OPTION 2
If you still want to check the option of storing the custom value in the Contacts DB, and integrate it into your query, you need to create a SyncAdapter.
This is basically a service that is able to sync contacts to/from a server into your own RawContact, which is then aggregated into one-or-more existing RawContacts, like Google does for Google Contacts.
You can set it to be notified when a new contact is added, and have your SyncAdapter add the needed info to the contact so it'll show links to your app.
If you go to your phone settings > accounts, you can see Whatsapp and Google's SyncAdapters there, where you can turn them off/on.
To create a sync adapter, you can follow the official docs, or this great tutorial.

Custom Contacts List in Android

I am looking to build a local Contacts list in Android. The user selects, say 3 contacts, from the address book and the code needs to save this list locally. The list should include Contact name, mobile number and email address. The user should also be able to edit this list. I am new to Android and struggling to get a solution for this.
The app I am building needs a user to create a local contacts list. I need to be able to extract the full contacts list from the Address Book and then the user gets to choose a limited number of contacts which get saved for later retrieval/modifications.

try Retrieving a List of Contacts in Android Developer.
This link may helps you to retrive the contact list.

Replace book objects with contact objects in the following tutorial and it might be useful...
http://stirfriedcode.blogspot.jp/2013/11/getting-specific-data-from-sqlite.html

I tried a new workaround and adapter-free solution . It's worth to have a look at :
https://github.com/draxdave/ConstraintAccordion

How to add one extra field to contact database?

I want to add one field(column) to contact fields,that i can set value for that field in code and mobile user can not see that field in contact properties.In this way i can use contact information without create another database to copy contact database.
Is this possible?
please help me

I don't think you can modify the contacts database directly (or at least not without rooting the device first).
If you want to add additional information to a stored contact, I think your best option would be to actually create a new database. Just create a new table with columns [CONTACT_ID, YOUR_NEW_FIELD] and store that extra piece of information on the contact there. Also, that way you won't be polluting the contact's database with your app's proprietary information, which would have no meaning if the user removed your app.

android contact list create groups

I am working on a contact list project and so far i can add,modify delete and search for a contact.and when i click on a contact i cand call him send email or sms.I have one table named contacts in my database with folowing fields id,name,phone number and email.
What i need to do next is create groups and add contacts to this groups.
Can you give me some ideas how to do this.I think i should do one more table in my database named groups for example which would have fields: group id ,group name ,contacts id.And i need to make a join to show contacts for a group.
Is this posible to create 2 tables in android database ?can you give me any example(tutorial on how to do this?

I think the best way to implement is to imitate Android Contacts database.Look at the Android contacts database itself.Its a bit complex but exactly what you can refer as to what tables and columns you might need in your app.
You can access that database by pulling out the file data/data/com.android.providers.contacts/databases/contacts.db from Eclipse File Explorer view in DDMS perspective when your Android emulator is running. The file name can also be contact2.db.
Then you can view the DB tables using "Sqlite DB Browser" which can be downloaded here.

Possibility of a custom Contacts field with a set list of values and Contacts lookup performance

I'm pretty sure it's not viable to do what I'd like to based on some initial research, but I figured it couldn't hurt to ask the community of experts here in case someone knows a way.
I'd like to create a custom field for contacts that the user is able to edit from the main Contacts app; however, the user should only be allowed to select from a list of four specific values. A short list of string values would be ideal, but an int with a min/max range would suffice.
I'm interested in knowing if it's possible either way, but also wondering if it make sense to go this route performance wise. More specifically, would it be better to look up a contact (based on a phone number) each time a call or SMS message is received or better to store my own set of data (consisting of name, numbers, and the custom field) and just syncing contact info in a thread every so often? Or syncing contacts the first time the app is run and then registering for changes using ContentObserver?
Here is a similar question with an answer that explains how to add a custom field to a contact.
Thanks in advance.

I don't see the purpose to have your own set of data against contacts stored in your separate database, as you obviously will run into sync issues. You can use the mimetype and store whatever you want against the contact, in the manner you linked.
Whenever you want to looup contacts you can do that by using your custom mimetype. You get the contact id (from ContactsContract.Data.CONTENT_URI), and then you run another query to get the contact details (from ContactsContract.Contacts.CONTENT_URI). Please note these are different tables.
I'd like to create a custom field for contacts that the user is able to edit from the main Contacts app
I don't see that possible, editable from the main app, when you use your custom mimetypes, and you don't have much options here. The main contact app will display only the fields that are in SDK. You can store details against contacts but they won't show up in the inbuilt edit contact screen.