database - What is the best way to get distinct contacts in Android

Question

I am successfully storing contacts in parse.com dashboard data browser by this code.

public void readContacts(){
         ContentResolver cr = getContentResolver();
         Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI,null, null, null, null);

         if (cur.getCount() > 0) {
            while (cur.moveToNext()) {
                String id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
                String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
                if (Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) ==1) {
                    System.out.println(name );
                    ParseObject testObject = new ParseObject("Contacts");

                    testObject.put("names", name);

                    // get the phone number
                    Cursor pCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,null,
                                           ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = ?",
                                           new String[]{id}, null);
                    while (pCur.moveToNext()) {
                          String phone = pCur.getString(
                                 pCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                         System.out.println( phone);
                        testObject.put("phonenumber", phone);

                    }
                    pCur.close();
                    testObject.saveInBackground();
           }
        }
     }
  }

But there is no check for the duplicate contacts !

It stores all the contacts duplicate from sim / phone memory.

How can it be avoided ?

One possible method I think is to store distinct names(contact) in local database, & then retrieving that data to store it in parse.com

Is there exists a better way ?

Thanks in advance...

Answer 1

An easy approach could be to load the data to a MatrixCursor with no duplicate data. For example lets assume you have a cursor c1 will many contacts, but you need a cursor with no duplicate data. Here is what you could do:

MatrixCursor mc = new MatrixCursor(new String[] { 
                        Phone._ID, 
                        Phone.DISPLAY_NAME_PRIMARY,
                        Phone.NUMBER
});

String lastNumber = "";

while(c1.moveToNext()){
    String id = c1.getString(c1.getColumnIndexOrThrow(Phone._ID));
    String name = c1.getString(c1.getColumnIndexOrThrow(Phone.DISPLAY_NAME_PRIMARY)));
    String number = c1.getString(c1.getColumnIndexOrThrow(Phone.NUMBER));

    //Some condition to check previous data is not matched and only then add row
    if(!lastNumber.contains(number)){
            lastNumber = number;
            mc.addRow(new String[]{id, name, number});
    }


}

c1.close();

Make an instance of MatrixCursor with same columns, and then load if last number or contact name does not match that of the previous contact. The condition for checking is upto you. Query data in some order so that the duplicate contacts stay together first.

Once the MatrixCursor is loaded you can fetch data from it. You could also attach it to a view through a custom CursorLoader or CursorAdapter.