java - Android 资源光标适配器 : Only one item displayed in ListView

Question

我正在开发一个适配器，它应该显示从 SQLite 数据库派生的项目列表。 ListView 嵌入在 Fragment 中，填充在自定义适配器中，该适配器是 ResourceCursorAdapter 的子类。迭代光标并打印其内容表明它包含许多条目。但是，仅针对第一个条目调用 bindView，它是 ListView 中显示的唯一条目。我做错了什么？

这是(精简的)代码:

XML 片段

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/network_settings"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:baselineAligned="false">

    <ListView
        android:id="@+id/addresses_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

适配器列表项 XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/addresses_list_item"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/remote_ip_address"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="0.45"/>

    <TextView
        android:id="@+id/remote_port"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="0.25"/>

    <TextView
        android:id="@+id/address_protocol"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:layout_weight="0.2"/>

    <ImageButton
        android:id="@+id/delete_address"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="@string/delete_address"
        android:src="@drawable/close"/>

</LinearLayout>

Fragment 类(经过简化，仅包含 onCreateView，因为这是实例化适配器的地方。片段本身工作正常)

public class NetworkSettingsFragment extends Fragment {

    private View mView;

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        mView = inflater.inflate(R.layout.network_settings, container, false);

        final SQLiteDatabase db = mActivity.getDatabase();
        final ListView addressesList = mView.findViewById(R.id.addresses_list);

        final String[] addrFields = new String[]{
            SettingsContract.AddressSettingsEntry._ID,
            SettingsContract.AddressSettingsEntry.IP_ADDRESS,
            SettingsContract.AddressSettingsEntry.PORT,
            SettingsContract.AddressSettingsEntry.PROTOCOL
        };
        final String sortOrder = SettingsContract.AddressSettingsEntry.IP_ADDRESS + " DESC";

        final Cursor addressesCursor = db.query(
            SettingsContract.AddressSettingsEntry.TABLE_NAME,
            addrFields,
            null,
            null,
            null,
            null,
            sortOrder
        );

        final AddressesListAdapter addressesListAdapter = new AddressesListAdapter(
            getActivity(), R.layout.address_list_item, addressesCursor, CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER
        );
        addressesList.setAdapter(addressesListAdapter);
    }
}

适配器

public class AddressesListAdapter extends ResourceCursorAdapter {

    final private static String TAG = "AddressesListAdapter";
    private int mLayout;

    public AddressesListAdapter(Context context, int layout, Cursor c, int flags) {
        super(context, layout, c, flags);
        mLayout = layout;
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return LayoutInflater.from(context).inflate(mLayout, parent, false);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        Log.d(TAG, "the view: " + view + "\ncursor: " + cursor.getPosition() + "\nnum items: " + cursor.getCount());

        TextView ipText = view.findViewById(R.id.remote_ip_address);
        TextView portText = view.findViewById(R.id.remote_port);
        TextView protocolText = view.findViewById(R.id.address_protocol);

        final long id = cursor.getLong(cursor.getColumnIndexOrThrow(SettingsContract.AddressSettingsEntry._ID));
        final String ip = cursor.getString(cursor.getColumnIndexOrThrow(SettingsContract.AddressSettingsEntry.IP_ADDRESS));
        final int port = cursor.getInt(cursor.getColumnIndexOrThrow(SettingsContract.AddressSettingsEntry.PORT));
        final String protocol = cursor.getString(cursor.getColumnIndexOrThrow(SettingsContract.AddressSettingsEntry.PROTOCOL));

        ipText.setText(ip);
        portText.setText(String.valueOf(port));
        protocolText.setText(protocol);
    }
}

Answer 1

回答我自己的问题:最终证明是布局问题。我没有考虑到的是，我的 Fragment 中的 ListView 是在 ScrollView 中创建的(这不是布局 xml 的一部分，我在我的问题中发布了。在该 ScrollView 中，选项列表(指向各种设置的链接)被包含 ListView 的 Fragment 替换。但是，原来的ScrollView并不一定能填满屏幕的整个高度，所以我只需要给ScrollView设置一个属性android:fillViewport即可> 的 XML 并将其设置为 true。这允许 ListView 拉伸(stretch)到屏幕底部和项目，其中我首先认为它们没有被考虑通过我的适配器，突然变得可见。

这是父 ScrollView 的简化源代码(在 FrameLayout 内)

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/settings_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:background="@color/colorDarkTransparentBackground">

    <ScrollView
        android:id="@+id/settings_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:paddingStart="20dp"
        android:paddingLeft="20dp"
        android:paddingTop="5dp"
        android:paddingEnd="20dp"
        android:paddingRight="20dp"
        android:paddingBottom="20dp"
        android:fillViewport="true"
        android:visibility="visible" />

</FrameLayout>