This lesson shows how to retrieve detail data for a contact, such as email addresses, phone numbers, and so forth. It's the details that users are looking for when they retrieve a contact. You can give them all the details for a contact, or only display details of a particular type, such as email addresses.
The steps in this lesson assume that you already have a
ContactsContract.Contacts
row for a contact the user has picked.
The Retrieving contact names lesson shows how to
retrieve a list of contacts.
Retrieve all details for a contact
To retrieve all the details for a contact, search the
ContactsContract.Data
table for any rows that contain the contact's
LOOKUP_KEY
. This column is available in
the ContactsContract.Data
table, because the Contacts
Provider makes an implicit join between the ContactsContract.Contacts
table and the ContactsContract.Data
table. The
LOOKUP_KEY
column is described
in more detail in the Retrieving contact names lesson.
Note: Retrieving all the details for a contact reduces the performance of a
device, because it needs to retrieve all of the columns in the
ContactsContract.Data
table. Consider the performance impact before
you use this technique.
Request permissions
To read from the Contacts Provider, your app must have
READ_CONTACTS
permission.
To request this permission, add the following child element of
<manifest>
to your manifest file:
<uses-permission android:name="android.permission.READ_CONTACTS" />
Set up a projection
Depending on the data type a row contains, it may use only a few columns or many. In addition,
the data is in different columns depending on the data type.
To ensure you get all the possible columns for all possible data types, you need to add all the
column names to your projection. Always retrieve
Data._ID
if you're binding the result
Cursor
to a ListView
; otherwise, the binding
won't work. Also retrieve Data.MIMETYPE
so you can identify the data type of each row you retrieve. For example:
Kotlin
private val PROJECTION: Array<out String> = arrayOf( ContactsContract.Data._ID, ContactsContract.Data.MIMETYPE, ContactsContract.Data.DATA1, ContactsContract.Data.DATA2, ContactsContract.Data.DATA3, ContactsContract.Data.DATA4, ContactsContract.Data.DATA5, ContactsContract.Data.DATA6, ContactsContract.Data.DATA7, ContactsContract.Data.DATA8, ContactsContract.Data.DATA9, ContactsContract.Data.DATA10, ContactsContract.Data.DATA11, ContactsContract.Data.DATA12, ContactsContract.Data.DATA13, ContactsContract.Data.DATA14, ContactsContract.Data.DATA15 )
Java
private static final String[] PROJECTION = { ContactsContract.Data._ID, ContactsContract.Data.MIMETYPE, ContactsContract.Data.DATA1, ContactsContract.Data.DATA2, ContactsContract.Data.DATA3, ContactsContract.Data.DATA4, ContactsContract.Data.DATA5, ContactsContract.Data.DATA6, ContactsContract.Data.DATA7, ContactsContract.Data.DATA8, ContactsContract.Data.DATA9, ContactsContract.Data.DATA10, ContactsContract.Data.DATA11, ContactsContract.Data.DATA12, ContactsContract.Data.DATA13, ContactsContract.Data.DATA14, ContactsContract.Data.DATA15 };
This projection retrieves all the columns for a row in the
ContactsContract.Data
table, using the column names defined in
the ContactsContract.Data
class.
Optionally, you can also use any other column constants defined in or inherited by the
ContactsContract.Data
class. Notice, however, that the columns
SYNC1
through
SYNC4
are meant to be used by sync
adapters, so their data is not useful.
Define the selection criteria
Define a constant for your selection clause, an array to hold selection arguments, and a
variable to hold the selection value. Use
the Contacts.LOOKUP_KEY
column to
find the contact. For example:
Kotlin
// Defines the selection clause private const val SELECTION: String = "${ContactsContract.Data.LOOKUP_KEY} = ?" ... // Defines the array to hold the search criteria private val selectionArgs: Array<String> = arrayOf("") /* * Defines a variable to contain the selection value. Once you * have the Cursor from the Contacts table, and you've selected * the desired row, move the row's LOOKUP_KEY value into this * variable. */ private var lookupKey: String? = null
Java
// Defines the selection clause private static final String SELECTION = Data.LOOKUP_KEY + " = ?"; // Defines the array to hold the search criteria private String[] selectionArgs = { "" }; /* * Defines a variable to contain the selection value. Once you * have the Cursor from the Contacts table, and you've selected * the desired row, move the row's LOOKUP_KEY value into this * variable. */ private lateinit var lookupKey: String
Using "?" as a placeholder in your selection text expression ensures that the resulting search is generated by binding rather than SQL compilation. This approach eliminates the possibility of malicious SQL injection.
Define the sort order
Define the sort order you want in the resulting Cursor
. To
keep all rows for a particular data type together, sort by
Data.MIMETYPE
. This query argument
groups all email rows together, all phone rows together, and so forth. For example:
Kotlin
/* * Defines a string that specifies a sort order of MIME type */ private const val SORT_ORDER = ContactsContract.Data.MIMETYPE
Java
/* * Defines a string that specifies a sort order of MIME type */ private static final String SORT_ORDER = ContactsContract.Data.MIMETYPE;
Note: Some data types don't use a subtype, so you can't sort on subtype.
Instead, you have to iterate through the returned Cursor
,
determine the data type of the current row, and store data for rows that use a subtype. When
you finish reading the cursor, you can then sort each data type by subtype and display the
results.
Initialize the Loader
Always do retrievals from the Contacts Provider (and all other content providers) in a
background thread. Use the Loader framework defined by the
LoaderManager
class and the
LoaderManager.LoaderCallbacks
interface to do background
retrievals.
When you're ready to retrieve the rows, initialize the loader framework by
calling initLoader()
. Pass an
integer identifier to the method; this identifier is passed to
LoaderManager.LoaderCallbacks
methods. The identifier helps you
use multiple loaders in an app by allowing you to differentiate between them.
The following snippet shows how to initialize the loader framework:
Kotlin
// Defines a constant that identifies the loader private const val DETAILS_QUERY_ID: Int = 0 class DetailsFragment : Fragment(), LoaderManager.LoaderCallbacks<Cursor> { ... override fun onCreate(savedInstanceState: Bundle?) { ... // Initializes the loader framework loaderManager.initLoader(DETAILS_QUERY_ID, null, this)
Java
public class DetailsFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> { ... // Defines a constant that identifies the loader static int DETAILS_QUERY_ID = 0; ... @Override public void onCreate(Bundle savedInstanceState) { ... // Initializes the loader framework getLoaderManager().initLoader(DETAILS_QUERY_ID, null, this);
Implement onCreateLoader()
Implement the onCreateLoader()
method, which is called by the loader framework immediately after you call
initLoader()
. Return a
CursorLoader
from this method. Since you're searching
the ContactsContract.Data
table, use the constant
Data.CONTENT_URI
as the content URI.
For example:
Kotlin
override fun onCreateLoader(loaderId: Int, args: Bundle?): Loader<Cursor> { // Choose the proper action mLoader = when(loaderId) { DETAILS_QUERY_ID -> { // Assigns the selection parameter selectionArgs[0] = lookupKey // Starts the query activity?.let { CursorLoader( it, ContactsContract.Data.CONTENT_URI, PROJECTION, SELECTION, selectionArgs, SORT_ORDER ) } } ... } return mLoader }
Java
@Override public Loader<Cursor> onCreateLoader(int loaderId, Bundle args) { // Choose the proper action switch (loaderId) { case DETAILS_QUERY_ID: // Assigns the selection parameter selectionArgs[0] = lookupKey; // Starts the query CursorLoader mLoader = new CursorLoader( getActivity(), ContactsContract.Data.CONTENT_URI, PROJECTION, SELECTION, selectionArgs, SORT_ORDER ); }
Implement onLoadFinished() and onLoaderReset()
Implement the
onLoadFinished()
method. The loader framework calls
onLoadFinished()
when the Contacts Provider returns the results of the query. For example:
Kotlin
override fun onLoadFinished(loader: Loader<Cursor>, data: Cursor) { when(loader.id) { DETAILS_QUERY_ID -> { /* * Process the resulting Cursor here. */ } ... } }
Java
@Override public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { switch (loader.getId()) { case DETAILS_QUERY_ID: /* * Process the resulting Cursor here. */ } break; ... } }
The method onLoaderReset()
is invoked when the loader framework detects that the data backing the result
Cursor
has changed. At this point, remove any existing references
to the Cursor
by setting them to null. If you don't, the loader
framework won't destroy the old Cursor
, and you'll get a memory
leak. For example:
Kotlin
override fun onLoaderReset(loader: Loader<Cursor>) { when (loader.id) { DETAILS_QUERY_ID -> { /* * If you have current references to the Cursor, * remove them here. */ } ... } }
Java
@Override public void onLoaderReset(Loader<Cursor> loader) { switch (loader.getId()) { case DETAILS_QUERY_ID: /* * If you have current references to the Cursor, * remove them here. */ } break; }
Retrieve specific details for a contact
Retrieving a specific data type for a contact, such as all the emails, follows the same pattern as retrieving all details. These are the only changes you need to make to the code listed in Retrieve all details for a contact:
- Projection
-
Modify your projection to retrieve the columns that are specific to the
data type. Also modify the projection to use the column name constants defined in the
ContactsContract.CommonDataKinds
subclass corresponding to the data type. - Selection
-
Modify the selection text to search for the
MIMETYPE
value that's specific to your data type. - Sort order
-
Since you're only selecting a single detail type, don't group the returned
Cursor
byData.MIMETYPE
.
These modifications are described in the following sections.
Define a projection
Define the columns you want to retrieve, using the column name constants in the subclass
of ContactsContract.CommonDataKinds
for the data type.
If you plan to bind your Cursor
to a ListView
,
be sure to retrieve the _ID
column. For example, to retrieve email data, define the
following projection:
Kotlin
private val PROJECTION: Array<String> = arrayOf( ContactsContract.CommonDataKinds.Email._ID, ContactsContract.CommonDataKinds.Email.ADDRESS, ContactsContract.CommonDataKinds.Email.TYPE, ContactsContract.CommonDataKinds.Email.LABEL )
Java
private static final String[] PROJECTION = { ContactsContract.CommonDataKinds.Email._ID, ContactsContract.CommonDataKinds.Email.ADDRESS, ContactsContract.CommonDataKinds.Email.TYPE, ContactsContract.CommonDataKinds.Email.LABEL };
Notice that this projection uses the column names defined in the class
ContactsContract.CommonDataKinds.Email
, instead of the column names
defined in the class ContactsContract.Data
. Using the email-specific
column names makes the code more readable.
In the projection, you can also use any of the other columns defined in the
ContactsContract.CommonDataKinds
subclass.
Define selection criteria
Define a search text expression that retrieves rows for a specific contact's
LOOKUP_KEY
and the
Data.MIMETYPE
of the details you
want. Enclose the MIMETYPE
value in
single quotes by concatenating a "'
" (single-quote) character to the start and end
of the constant; otherwise, the provider interprets the constant as a variable name rather
than as a string value. You don't need to use a placeholder for this value, because you're
using a constant rather than a user-supplied value. For example:
Kotlin
/* * Defines the selection clause. Search for a lookup key * and the Email MIME type */ private const val SELECTION = "${ContactsContract.Data.LOOKUP_KEY} = ? AND " + "${ContactsContract.Data.MIMETYPE} = '${Email.CONTENT_ITEM_TYPE}'" ... // Defines the array to hold the search criteria private val selectionArgs: Array<String> = arrayOf("")
Java
/* * Defines the selection clause. Search for a lookup key * and the Email MIME type */ private static final String SELECTION = Data.LOOKUP_KEY + " = ?" + " AND " + Data.MIMETYPE + " = " + "'" + Email.CONTENT_ITEM_TYPE + "'"; // Defines the array to hold the search criteria private String[] selectionArgs = { "" };
Define a sort order
Define a sort order for the returned Cursor
. Since you're retrieving a
specific data type, omit the sort on MIMETYPE
.
Instead, if the type of detail data you're searching includes a subtype, sort on it.
For example, for email data you can sort on
Email.TYPE
:
Kotlin
private const val SORT_ORDER: String = "${Email.TYPE} ASC"
Java
private static final String SORT_ORDER = Email.TYPE + " ASC ";