Question

I’m trying to use the following code to grab a random mobile phone number from the contacts:

    ContentResolver cr = getContentResolver();
    Cursor cursor = cr.query(ContactsContract.Contacts.CONTENT_URI, null, "DISPLAY_NAME = '" + "NAME" + "'", null, null);
    cursor.moveToFirst();
    String contactId = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID));
    Cursor phones = cr.query(Phone.CONTENT_URI, null, Phone.CONTACT_ID + " = " + contactId, null, null);
    List numbers = new ArrayList();

    while (phones.moveToNext()) {
        String number = phones.getString(phones.getColumnIndex(Phone.NUMBER));
        int type = phones.getInt(phones.getColumnIndex(Phone.TYPE));
        switch (type) {
            case Phone.TYPE_MOBILE:
                numbers.add(number);
                break;
        }
    }

    Random randGen = new Random();
    return (String) numbers.get(randGen.nextInt(numbers.size()));

However, running this code produces a crash on line 4, with a message saying “CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0”. The crash seems to be caused by the cursor.getString() method. Does anyone know where I’m going wrong? This is using the ContactsContract in Android 2.1. Eclipse gives no errors.

Thanks!

Answer 1

The moveToFirst() method returns a boolean. It returns true if it was able to move to the first row and false otherwise, indicating that the query returned an empty set.

When using a cursor, you should follow something like:

if (cursor.moveToFirst()) {
    do {
        // do some stuff
    } while (cursor.moveToNext());
}
cursor.close();