顯示快速聯絡標記

本頁面說明如何將 QuickContactBadge 新增至 UI，以及如何將資料繫結至該 UI。QuickContactBadge 是最初顯示為縮圖圖片的小工具。雖然您可以使用任何 Bitmap 做為縮圖圖片，但通常會使用從聯絡人相片縮圖圖片解碼的 Bitmap。

小型圖片就是控制項。當使用者輕觸圖片時，QuickContactBadge 會展開為包含以下內容的對話方塊：

大型圖片
與聯絡人相關聯的大型圖片，如果沒有圖片，則會顯示預留位置圖示。
應用程式圖示
每個內建應用程式可處理詳細資料資料的應用程式圖示。舉例來說，如果聯絡人的詳細資料包含一或多個電子郵件地址，系統就會顯示電子郵件圖示。使用者輕觸圖示時，系統會顯示所有聯絡人的電子郵件地址。當使用者輕觸其中一個地址時，電子郵件應用程式會顯示一則畫面，讓使用者撰寫要傳送給所選電子郵件地址的郵件。

QuickContactBadge 檢視畫面可讓您立即存取聯絡人的詳細資料，並快速與聯絡人聯絡。使用者不必查詢、找出並複製資訊，然後貼到適當的應用程式中。他們可以改為輕觸 QuickContactBadge 並選擇要使用的通訊方式，然後將該方法的資訊直接傳送到適當的應用程式。

新增 QuickContactBadge 檢視

如要新增 QuickContactBadge，請在版面配置中插入 <QuickContactBadge> 元素，如以下範例所示：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
...
    <QuickContactBadge
               android:id=@+id/quickbadge
               android:layout_height="wrap_content"
               android:layout_width="wrap_content"
               android:scaleType="centerCrop"/>
    ...
</RelativeLayout>

擷取供應商資料

如要在 QuickContactBadge 中顯示聯絡人，請備妥聯絡人的內容 URI，並為小圖片備妥 Bitmap。您可以從聯絡人供應器擷取的資料欄產生內容 URI 和 Bitmap。請在您要將資料載入 Cursor 的投影中指定這些資料欄。

針對 Android 3.0 (API 級別 11) 以上版本，請在投影中加入下列欄：

如果是 Android 2.3.3 (API 級別 10) 以下版本，請使用下列資料欄：

本頁範例假設已載入包含這些欄和任何其他所選欄的 Cursor。如要瞭解如何擷取 Cursor 中的欄，請參閱「擷取聯絡人名單」一文。

設定聯絡人 URI 和縮圖

取得必要的資料欄後，您可以將資料繫結至 QuickContactBadge。

設定聯絡人 URI

如要設定聯絡人的內容 URI，請呼叫 getLookupUri(id,lookupKey) 來取得 CONTENT_LOOKUP_URI，然後呼叫 assignContactUri() 來設定聯絡人。如以下範例所示：

Kotlin

    // The Cursor that contains contact rows
    var cursor: Cursor? = null
    // The index of the _ID column in the Cursor
    var idColumn: Int = 0
    // The index of the LOOKUP_KEY column in the Cursor
    var lookupKeyColumn: Int = 0
    // A content URI for the desired contact
    var contactUri: Uri? = null
    // A handle to the QuickContactBadge view
    ...
    cursor?.let { cursor ->
        /*
         * Insert code here to move to the desired cursor row
         */
        // Gets the _ID column index
        idColumn = cursor.getColumnIndex(ContactsContract.Contacts._ID)
        // Gets the LOOKUP_KEY index
        lookupKeyColumn = cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY)
        // Gets a content URI for the contact
        contactUri = ContactsContract.Contacts.getLookupUri(
                cursor.getLong(idColumn),
                cursor.getString(lookupKeyColumn)
        )
        binding.badge.assignContactUri(contactUri)
    }

Java

    // The Cursor that contains contact rows
    Cursor cursor;
    // The index of the _ID column in the Cursor
    int idColumn;
    // The index of the LOOKUP_KEY column in the Cursor
    int lookupKeyColumn;
    // A content URI for the desired contact
    Uri contactUri;
    ...
    /*
     * Insert code here to move to the desired cursor row
     */
    // Gets the _ID column index
    idColumn = cursor.getColumnIndex(ContactsContract.Contacts._ID);
    // Gets the LOOKUP_KEY index
    lookupKeyColumn = cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY);
    // Gets a content URI for the contact
    contactUri =
            Contacts.getLookupUri(
                cursor.getLong(idColumn),
                cursor.getString(lookupKeyColumn)
            );
    binding.badge.assignContactUri(contactUri);

使用者輕觸 QuickContactBadge 圖示時，對話方塊中會顯示聯絡人的詳細資料。

設定相片縮圖

為 QuickContactBadge 設定聯絡人 URI 不會自動載入聯絡人的縮圖相片。如要載入相片，請從聯絡人的 Cursor 列取得相片的 URI，然後使用該 URI 開啟包含已壓縮縮圖相片的檔案，並將檔案讀取至 Bitmap。

注意：PHOTO_THUMBNAIL_URI 欄不適用於 3.0 之前的平台版本。對於這些版本，您必須從 Contacts.Photo 子表擷取 URI。

首先，請設定變數，以便存取包含 Contacts._ID 和 Contacts.LOOKUP_KEY 欄的 Cursor：

Kotlin

    // The column in which to find the thumbnail ID
    var thumbnailColumn: Int = 0
    /*
     * The thumbnail URI, expressed as a String.
     * Contacts Provider stores URIs as String values.
     */
    var thumbnailUri: String? = null
    ...
    cursor?.let { cursor ->
        /*
         * Gets the photo thumbnail column index if
         * platform version >= Honeycomb
         */
        thumbnailColumn = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            cursor.getColumnIndex(ContactsContract.Contacts.PHOTO_THUMBNAIL_URI)
            // Otherwise, sets the thumbnail column to the _ID column
        } else {
            idColumn
        }
        /*
         * Assuming the current Cursor position is the contact you want,
         * gets the thumbnail ID
         */
        thumbnailUri = cursor.getString(thumbnailColumn)
    }

Java

    // The column in which to find the thumbnail ID
    int thumbnailColumn;
    /*
     * The thumbnail URI, expressed as a String.
     * Contacts Provider stores URIs as String values.
     */
    String thumbnailUri;
    ...
    /*
     * Gets the photo thumbnail column index if
     * platform version >= Honeycomb
     */
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        thumbnailColumn =
                cursor.getColumnIndex(ContactsContract.Contacts.PHOTO_THUMBNAIL_URI);
    // Otherwise, sets the thumbnail column to the _ID column
    } else {
        thumbnailColumn = idColumn;
    }
    /*
     * Assuming the current Cursor position is the contact you want,
     * gets the thumbnail ID
     */
    thumbnailUri = cursor.getString(thumbnailColumn);
    ...

定義方法，為目的地檢視畫面擷取聯絡人和尺寸的相片相關資料，並在 Bitmap 中傳回正確尺寸的縮圖。首先，請建構指向縮圖的 URI：

Kotlin

    /**
     * Load a contact photo thumbnail and return it as a Bitmap,
     * resizing the image to the provided image dimensions as needed.
     * @param photoData photo ID Prior to Honeycomb, the contact's _ID value.
     * For Honeycomb and later, the value of PHOTO_THUMBNAIL_URI.
     * @return A thumbnail Bitmap, sized to the provided width and height.
     * Returns null if the thumbnail is not found.
     */
    private fun loadContactPhotoThumbnail(photoData: String): Bitmap? {
        // Creates an asset file descriptor for the thumbnail file
        var afd: AssetFileDescriptor? = null
        // try-catch block for file not found
        try {
            // Creates a holder for the URI
            val thumbUri: Uri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                // If Android 3.0 or later,
                // sets the URI from the incoming PHOTO_THUMBNAIL_URI
                Uri.parse(photoData)
            } else {
                // Prior to Android 3.0, constructs a photo Uri using _ID
                /*
                 * Creates a contact URI from the Contacts content URI
                 * incoming photoData (_ID)
                 */
                val contactUri: Uri =
                        Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_URI, photoData)
                /*
                 * Creates a photo URI by appending the content URI of
                 * Contacts.Photo
                 */
                Uri.withAppendedPath(contactUri, ContactsContract.Contacts.Photo.CONTENT_DIRECTORY)
            }

            /*
             * Retrieves an AssetFileDescriptor object for the thumbnail URI
             * using ContentResolver.openAssetFileDescriptor
             */
            afd = activity?.contentResolver?.openAssetFileDescriptor(thumbUri, "r")
            /*
             * Gets a file descriptor from the asset file descriptor.
             * This object can be used across processes.
             */
            return afd?.fileDescriptor?.let {fileDescriptor ->
                // Decodes the photo file and returns the result as a Bitmap
                // if the file descriptor is valid
                BitmapFactory.decodeFileDescriptor(fileDescriptor, null, null)
            }
        } catch (e: FileNotFoundException) {
            /*
             * Handle file not found errors
             */
            null
        } finally {
            // In all cases, close the asset file descriptor
            try {
                afd?.close()
            } catch (e: IOException) {
            }
        }
    }

Java

    /**
     * Load a contact photo thumbnail and return it as a Bitmap,
     * resizing the image to the provided image dimensions as needed.
     * @param photoData photo ID Prior to Honeycomb, the contact's _ID value.
     * For Honeycomb and later, the value of PHOTO_THUMBNAIL_URI.
     * @return A thumbnail Bitmap, sized to the provided width and height.
     * Returns null if the thumbnail is not found.
     */
    private Bitmap loadContactPhotoThumbnail(String photoData) {
        // Creates an asset file descriptor for the thumbnail file
        AssetFileDescriptor afd = null;
        // try-catch block for file not found
        try {
            // Creates a holder for the URI
            Uri thumbUri;
            // If Android 3.0 or later
            if (Build.VERSION.SDK_INT
                    >=
                Build.VERSION_CODES.HONEYCOMB) {
                // Sets the URI from the incoming PHOTO_THUMBNAIL_URI
                thumbUri = Uri.parse(photoData);
            } else {
            // Prior to Android 3.0, constructs a photo Uri using _ID
                /*
                 * Creates a contact URI from the Contacts content URI
                 * incoming photoData (_ID)
                 */
                final Uri contactUri = Uri.withAppendedPath(
                        ContactsContract.Contacts.CONTENT_URI, photoData);
                /*
                 * Creates a photo URI by appending the content URI of
                 * Contacts.Photo
                 */
                thumbUri =
                        Uri.withAppendedPath(
                                contactUri, ContactsContract.Contacts.Photo.CONTENT_DIRECTORY);
            }

        /*
         * Retrieves an AssetFileDescriptor object for the thumbnail URI
         * using ContentResolver.openAssetFileDescriptor
         */
        afd = getActivity().getContentResolver().
                openAssetFileDescriptor(thumbUri, "r");
        /*
         * Gets a file descriptor from the asset file descriptor.
         * This object can be used across processes.
         */
        FileDescriptor fileDescriptor = afd.getFileDescriptor();
        // Decodes the photo file and returns the result as a Bitmap
        // if the file descriptor is valid
        if (fileDescriptor != null) {
            // Decodes the bitmap
            return BitmapFactory.decodeFileDescriptor(
                    fileDescriptor, null, null);
            }
        // If the file isn't found
        } catch (FileNotFoundException e) {
            /*
             * Handle file not found errors
             */
        // In all cases, close the asset file descriptor
        } finally {
            if (afd != null) {
                try {
                    afd.close();
                } catch (IOException e) {}
            }
        }
        return null;
    }

呼叫程式碼中的 loadContactPhotoThumbnail() 方法以取得縮圖 Bitmap，然後使用結果設定 QuickContactBadge 中的相片縮圖：

Kotlin

    ...
    /*
     * Decodes the thumbnail file to a Bitmap
     */
    mThumbnailUri?.also { thumbnailUri ->
        loadContactPhotoThumbnail(thumbnailUri).also { thumbnail ->
            /*
             * Sets the image in the QuickContactBadge.
             * QuickContactBadge inherits from ImageView.
             */
            badge.setImageBitmap(thumbnail)
        }
    }

Java

    ...
    /*
     * Decodes the thumbnail file to a Bitmap
     */
    Bitmap mThumbnail =
            loadContactPhotoThumbnail(thumbnailUri);
    /*
     * Sets the image in the QuickContactBadge.
     * QuickContactBadge inherits from ImageView.
     */
    badge.setImageBitmap(mThumbnail);

將 QuickContactBadge 新增至 ListView

QuickContactBadge 是顯示聯絡人清單的 ListView 實用附加元件。使用 QuickContactBadge 顯示每個聯絡人的縮圖相片；當使用者輕觸縮圖時，QuickContactBadge 對話方塊就會顯示。

新增 QuickContactBadge 元素

首先，請將 QuickContactBadge 檢視畫面元素新增至項目版面配置。舉例來說，如果您想為每個擷取的聯絡人顯示 QuickContactBadge 和名稱，請將下列 XML 放入版面配置檔案：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
    <QuickContactBadge
        android:id="@+id/quickcontact"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:scaleType="centerCrop"/>
    <TextView android:id="@+id/displayname"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_toRightOf="@+id/quickcontact"
              android:gravity="center_vertical"
              android:layout_alignParentRight="true"
              android:layout_alignParentTop="true"/>
</RelativeLayout>

在後續章節中，我們會將此檔案稱為 contact_item_layout.xml。

設定自訂 CursorAdapter

如要將 CursorAdapter 繫結至包含 QuickContactBadge 的 ListView，請定義可擴充 CursorAdapter 的自訂轉接器。您可以先在 Cursor 中處理資料，再將資料繫結至 QuickContactBadge。這個方法還可讓您將多個 Cursor 欄繫結至 QuickContactBadge。在一般的 CursorAdapter 中，這兩種作業都不可能。

您定義的 CursorAdapter 子類別必須覆寫下列方法：

CursorAdapter.newView()
以新 View 物件將項目版面配置保留在內。在這個方法的覆寫值中，將子項 View 物件 (包括子項 QuickContactBadge) 的句柄儲存起來。採用這種做法，您就不必在每次將新版面配置加載時，取得子項 View 物件的句柄。

您必須覆寫這個方法，才能取得個別子項 View 物件的處理常式。這項技巧可讓您在 CursorAdapter.bindView() 中控管綁定。

CursorAdapter.bindView()
將資料從目前的 Cursor 列移至項目版面配置的子項 View 物件。您必須覆寫這個方法，才能將聯絡人的 URI 和縮圖綁定至 QuickContactBadge。預設實作方式只允許資料欄與 View 之間的一對一對應。

以下程式碼片段包含 CursorAdapter 的自訂子類別範例：

定義自訂清單 Adapter

定義 CursorAdapter 的子類別，包括其建構函式，並覆寫 newView() 和 bindView()：

Kotlin

    /**
     * Defines a class that holds resource IDs of each item layout
     * row to prevent having to look them up each time data is
     * bound to a row
     */
    private data class ViewHolder(
            internal var displayname: TextView? = null,
            internal var quickcontact: QuickContactBadge? = null
    )

    /**
     *
     *
     */
    private inner class ContactsAdapter(
            context: Context,
            val inflater: LayoutInflater = LayoutInflater.from(context)
    ) : CursorAdapter(context, null, 0) {
        ...
        override fun newView(
                context: Context,
                cursor: Cursor,
                viewGroup: ViewGroup
        ): View {
            /* Inflates the item layout. Stores view references
             * in a ViewHolder class to prevent having to look
             * them up each time bindView() is called.
             */
            return ContactListLayoutBinding.inflate(inflater,
                    viewGroup,
                    false).also { binding ->
                view.tag = ViewHolder().apply {
                    displayname = binding.displayname
                    quickcontact = binding.quickcontact
                }
            }.root
        }
        ...
        override fun bindView(view: View?, context: Context?, cursor: Cursor?) {
            (view?.tag as? ViewHolder)?.also { holder ->
                cursor?.apply {
                    ...
                    // Sets the display name in the layout
                    holder.displayname?.text = getString(displayNameIndex)
                    ...
                    /*
                     * Generates a contact URI for the QuickContactBadge
                     */
                    ContactsContract.Contacts.getLookupUri(
                            getLong(idIndex),
                            cursor.getString(lookupKeyIndex)
                    ).also { contactUri ->
                        holder.quickcontact?.assignContactUri(contactUri)
                    }

                    getString(photoDataIndex)?.also {photoData ->
                        /*
                         * Decodes the thumbnail file to a Bitmap.
                         * The method loadContactPhotoThumbnail() is defined
                         * in the section "Set the contact URI and thumbnail."
                         */
                        loadContactPhotoThumbnail(photoData)?.also { thumbnailBitmap ->
                            /*
                             * Sets the image in the QuickContactBadge.
                             * QuickContactBadge inherits from ImageView.
                             */
                            holder.quickcontact?.setImageBitmap(thumbnailBitmap)
                        }
                    }
                }
            }

        }
    }

Java

    private class ContactsAdapter extends CursorAdapter {
        private LayoutInflater inflater;
        ...
        public ContactsAdapter(Context context) {
            super(context, null, 0);

            /*
             * Gets an inflater that can instantiate
             * the ListView layout from the file
             */
            inflater = LayoutInflater.from(context);
            ...
        }
        ...
        /**
         * Defines a class that holds resource IDs of each item layout
         * row to prevent having to look them up each time data is
         * bound to a row
         */
        private class ViewHolder {
            TextView displayname;
            QuickContactBadge quickcontact;
        }
        ...
        @Override
        public View newView(
                Context context,
                Cursor cursor,
                ViewGroup viewGroup) {
            /* Inflates the item layout. Stores view references
             * in a ViewHolder class to prevent having to look
             * them up each time bindView() is called.
             */
            final ContactListLayoutBinding binding =
            ContactListLayoutBinding.inflate(inflater, 
                viewGroup,
                false);
            final ViewHolder holder = new ViewHolder();
            holder.displayname =
                    binding.displayName;
            holder.quickcontact =
                    binding.quickContact;
            view.setTag(holder);
            return binding.root;
        }
        ...
        @Override
        public void bindView(
                View view,
                Context context,
                Cursor cursor) {
            final ViewHolder holder = (ViewHolder) view.getTag();
            final String photoData =
                    cursor.getString(photoDataIndex);
            final String displayName =
                    cursor.getString(displayNameIndex);
            ...
            // Sets the display name in the layout
            holder.displayname = cursor.getString(displayNameIndex);
            ...
            /*
             * Generates a contact URI for the QuickContactBadge
             */
            final Uri contactUri = Contacts.getLookupUri(
                    cursor.getLong(idIndex),
                    cursor.getString(lookupKeyIndex));
            holder.quickcontact.assignContactUri(contactUri);
            String photoData = cursor.getString(photoDataIndex);
            /*
             * Decodes the thumbnail file to a Bitmap.
             * The method loadContactPhotoThumbnail() is defined
             * in the section "Set the contact URI and thumbnail."
             */
            Bitmap thumbnailBitmap =
                    loadContactPhotoThumbnail(photoData);
            /*
             * Sets the image in the QuickContactBadge.
             * QuickContactBadge inherits from ImageView.
             */
            holder.quickcontact.setImageBitmap(thumbnailBitmap);
    }

設定變數

在程式碼中設定變數，包括包含必要欄位的 Cursor 投影，如下例所示。

注意：下列程式碼片段使用「設定聯絡人 URI 和縮圖」一節中所定義的 loadContactPhotoThumbnail() 方法。

Kotlin

/*
 * Defines a projection based on platform version. This ensures
 * that you retrieve the correct columns.
 */
private val PROJECTION: Array<out String> = arrayOf(
        ContactsContract.Contacts._ID,
        ContactsContract.Contacts.LOOKUP_KEY,
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
        } else {
            ContactsContract.Contacts.DISPLAY_NAME
        },
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            ContactsContract.Contacts.PHOTO_FILE_ID
        } else {
            /*
             * Although it's not necessary to include the
             * column twice, this keeps the number of
             * columns the same regardless of version
             */
            ContactsContract.Contacts._ID
        }
)
...
class ContactsFragment : Fragment(), LoaderManager.LoaderCallbacks<Cursor> {
    ...
    // Defines a ListView
    private val listView: ListView? = null
    // Defines a ContactsAdapter
    private val adapter: ContactsAdapter? = null
    ...
    // Defines a Cursor to contain the retrieved data
    private val cursor: Cursor? = null
    /*
     * As a shortcut, defines constants for the
     * column indexes in the Cursor. The index is
     * 0-based and always matches the column order
     * in the projection.
     */
    // Column index of the _ID column
    private val idIndex = 0
    // Column index of the LOOKUP_KEY column
    private val lookupKeyIndex = 1
    // Column index of the display name column
    private val displayNameIndex = 3
    /*
     * Column index of the photo data column.
     * It's PHOTO_THUMBNAIL_URI for Honeycomb and later,
     * and _ID for previous versions.
     */
    private val photoDataIndex: Int =
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) 3 else 0
    ...

Java

public class ContactsFragment extends Fragment implements
        LoaderManager.LoaderCallbacks<Cursor> {
...
    // Defines a ListView
    private ListView listView;
    // Defines a ContactsAdapter
    private ContactsAdapter adapter;
    ...
    // Defines a Cursor to contain the retrieved data
    private Cursor cursor;
    /*
     * Defines a projection based on platform version. This ensures
     * that you retrieve the correct columns.
     */
    private static final String[] PROJECTION =
            {
                ContactsContract.Contacts._ID,
                ContactsContract.Contacts.LOOKUP_KEY,
                (Build.VERSION.SDK_INT >=
                 Build.VERSION_CODES.HONEYCOMB) ?
                        ContactsContract.Contacts.DISPLAY_NAME_PRIMARY :
                        ContactsContract.Contacts.DISPLAY_NAME
                (Build.VERSION.SDK_INT >=
                 Build.VERSION_CODES.HONEYCOMB) ?
                        ContactsContract.Contacts.PHOTO_FILE_ID :
                        /*
                         * Although it's not necessary to include the
                         * column twice, this keeps the number of
                         * columns the same regardless of version
                         */
                        ContactsContract.Contacts._ID
            };
    /*
     * As a shortcut, defines constants for the
     * column indexes in the Cursor. The index is
     * 0-based and always matches the column order
     * in the projection.
     */
    // Column index of the _ID column
    private int idIndex = 0;
    // Column index of the LOOKUP_KEY column
    private int lookupKeyIndex = 1;
    // Column index of the display name column
    private int displayNameIndex = 3;
    /*
     * Column index of the photo data column.
     * It's PHOTO_THUMBNAIL_URI for Honeycomb and later,
     * and _ID for previous versions.
     */
    private int photoDataIndex =
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
            3 :
            0;
    ...

設定 ListView

在 Fragment.onCreate() 中，將自訂遊標轉接器執行個體化，並取得 ListView 的控制代碼：

Kotlin

    override fun onCreateView(
            inflater: LayoutInflater,
            container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        return FragmentListViewBinding.inflate(...).let { binding ->
            ...
            /*
             * Gets a handle to the ListView in the file
             * contact_list_layout.xml
             */
            listView = binding.contactList
            mAdapter?.also {
                listView?.adapter = it
            }
            ...
        }.root
    }
    ...

Java

    @Override
    public View onCreateView(LayoutInflater inflater,
            ViewGroup container, Bundle savedInstanceState) {
        FragmentListViewBinding binding = FragmentListViewBinding.inflate(...)
        ...
        /*
         * Gets a handle to the ListView in the file
         * contact_list_layout.xml
         */
        if (binding.contactListView != null && adapter != null) {
            binding.contactListView.setAdapter(adapter);
        }
        ...
    }
    ...

在 onViewCreated() 中，將 ContactsAdapter 繫結至 ListView：

Kotlin

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    /*
     * Instantiates the subclass of
     * CursorAdapter
     */
    mAdapter = activity?.let {
        ContactsAdapter(it).also { adapter ->
            // Sets up the adapter for the ListView
            listView?.adapter = adapter
        }
    }
}

Java

@Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        ...
        /*
         * Instantiates the subclass of
         * CursorAdapter
         */
        mAdapter = new ContactsAdapter(getActivity());
        // Sets up the adapter for the ListView
        if (listView != null && mAdapter != null) {
            listView.setAdapter(mAdapter);
        }
        ...
    }
    ...

當您收到包含聯絡人資料的 Cursor (通常位於 onLoadFinished() 中) 時，請呼叫 swapCursor() 將 Cursor 資料移至 ListView。這會針對聯絡人清單中的每個項目顯示 QuickContactBadge。

Kotlin

override fun onLoadFinished(loader: Loader<Cursor>, cursor: Cursor) {
    // When the loader has completed, swap the cursor into the adapter
    mAdapter?.swapCursor(cursor)
}

Java

public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
        // When the loader has completed, swap the cursor into the adapter
        mAdapter.swapCursor(cursor);
    }

使用 CursorAdapter (或子類別) 將 Cursor 繫結至 ListView 並使用 CursorLoader 載入 Cursor 時，請一律在 onLoaderReset() 的實作中清除 Cursor 的參照。如以下範例所示：

Kotlin

    override fun onLoaderReset(loader: Loader<Cursor>) {
        // Removes remaining reference to the previous Cursor
        adapter?.swapCursor(null)
    }

Java

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // Removes remaining reference to the previous Cursor
        adapter.swapCursor(null);
    }