Android contacts cache

ContactsCache.java

/**
 * Cache for addressbook contacts.
 */
public class ContactsCache {

   private static class Holder {
        static final ContactsCache INSTANCE = new ContactsCache();
    }

    /**
     * The activity context.
     */
    private Context mContext;

    /**
     * Contacts table.
     */
    private SparseArray<Contact> mContactsTable;

    /**
     * Contacts list.
     */
    private List<Contact> mContactsList;

    public ContactsCache() {
    }

    public static ContactsCache getInstance() {
        return Holder.INSTANCE;
    }

    /**
     * Sets the context.
     * @param context
     */
    public void init(Context context) {
        this.mContext = context;
    }

    /**
     * Get a particular contact.
     * @param contactId The addressbook id of the contact.
     * @return The Contact or null if not found
     */
    public Contact getContact(int contactId) {
        return getContactsTable().get(contactId);
    }

    /**
     * Gets the contacts list.
     * @return
     */
    public List<Contact> getContactsList() {
        if(mContactsList == null) {
            mContactsList = new ArrayList<>(getContactsTable().size());
            for(int i = 0; i < getContactsTable().size(); i++) {
                mContactsList.add(getContactsTable().valueAt(i));
            }
            Collections.sort(mContactsList);
        }

        return mContactsList;
    }

    /**
     * Gets the contacts table.
     * @return
     */
    private SparseArray<Contact> getContactsTable() {
        if(mContactsTable == null) {
            mContactsTable = loadContactsFromAddressBook();
        }
        return mContactsTable;
    }

    /**
     * Loads the contacts contained in the phone address book.
     * @return
     */
    protected SparseArray<Contact> loadContactsFromAddressBook() {
        SparseArray<Contact> contactsTable = new SparseArray<>();
        Cursor phones = mContext.getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME);

        if(phones != null) {
            while (phones.moveToNext()) {
                int id = phones.getInt(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone._ID));
                String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                int phoneType = phones.getInt(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE));
                int phoneTypeStringRes = ContactsContract.CommonDataKinds.Phone.getTypeLabelResource(phoneType);

                Contact tmpContact = new Contact(String.valueOf(id), name, phoneNumber, mContext.getString(phoneTypeStringRes));
                contactsTable.put(id, tmpContact);
            }

            phones.close();
        }

        return contactsTable;
    }
}