Question

我需要有多个CursorAdapter，以便每个都引用某个片段。但是我注意到只有一个CursorAdapter正在工作。我需要知道应该做些什么来使两者都有效。

PlatformCursorAdapter访问表存储

public class PlatformCursorAdapter extends CursorAdapter {

private static final String LOG_TAG = PlatformCursorAdapter.class.getName();

public PlatformCursorAdapter(Context context, Cursor cursor){
    super(context, cursor, 0);
}

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

@Override
public void bindView(final View view, final Context context, Cursor cursor) {
    //find which fields should be populated
    TextView itemName = (TextView) view.findViewById(R.id.item_name);
    TextView itemPrice = (TextView) view.findViewById(R.id.item_price);
    final TextView itemQuantity = (TextView) view.findViewById(R.id.item_quantity);
    final TextView itemWeight = view.findViewById(R.id.item_weight);
    TextView supplierName = (TextView) view.findViewById(R.id.item_supplier_name);
    TextView supplierNumber = (TextView) view.findViewById(R.id.item_supplier_number);

    //find the columns of pets we're interested in
    final String mItemName = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_PRODUCT_NAME));
    String mItemPrice = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_PRODUCT_PRICE));
    final String mItemQuantity = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_PRODUCT_QUANTITY));
    final String mItemWeight = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_PRODUCT_WEIGHT));
    String mSupplierName = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_SUPPLIER_NAME));
    final String mSupplierNumber = cursor.getString(cursor.getColumnIndex(StoreEntry.COLUMN_SUPPLIER_NUMBER));

    //get current item id
    int currentId = cursor.getInt(cursor.getColumnIndex(StoreEntry._ID));
    //Create the content Uri for the current Id
    final Uri contentUri = Uri.withAppendedPath(StoreEntry.CONTENT_URI, Integer.toString(currentId));

    //populate fields RecipeFragment
    itemName.setText(mItemName);
    itemPrice.setText(mItemPrice);
    itemQuantity.setText(mItemQuantity);
    itemWeight.setText(mItemWeight);
    supplierName.setText(mSupplierName);
    supplierNumber.setText(mSupplierNumber);
}
}

这是访问收件人表的RecipeCursorAdapter

public class RecipeCursorAdapter extends CursorAdapter {

private static final String LOG_TAG = RecipeCursorAdapter.class.getName();

public RecipeCursorAdapter (Context context, Cursor cursor1){
    super(context, cursor1, 0);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    return LayoutInflater.from(context).inflate(R.layout.recipe_activity, parent, false);
}

@Override
public void bindView(View view, Context context, Cursor cursor) {
    //find which fields would be populated
    TextView recipeName = view.findViewById(R.id.recipe_name);
    TextView recipeType = view.findViewById(R.id.recipe_type);
    TextView recipeServings = view.findViewById(R.id.recipe_servings);
    TextView recipeValues = view.findViewById(R.id.ingrediant_name_1);

    //get the data from the table recipes
    Log.e(LOG_TAG, "Number of Columns " + cursor.getColumnCount());
    Log.e(LOG_TAG, "This is the Cursor Location " + cursor.getColumnIndex(RecipeEntry.COLUMN_RECIPE_SERVINGS));
    String mRecipeName = cursor.getString(cursor.getColumnIndex(RecipeEntry.COLUMN_RECIPE_NAME));
    String mRecipeType = cursor.getString(cursor.getColumnIndex(RecipeEntry.COLUMN_RECIPE_TYPE));
    String mRecipeServings = cursor.getString(cursor.getColumnIndex(RecipeEntry.COLUMN_RECIPE_SERVINGS));
    String mRecipeValues = cursor.getString(cursor.getColumnIndex(RecipeEntry.COLUMN_RECIPE_VALUES));

    //get current item Id
    int currenId = cursor.getInt(cursor.getColumnIndex(RecipeEntry._ID));
    //create a content Uri for the current Id
    final Uri contentUri = Uri.withAppendedPath(RecipeEntry.CONTENT_URI, Integer.toString(currenId));

    //populate fields with their respective data
    recipeName.setText(mRecipeName);
    recipeType.setText(mRecipeType);
    recipeServings.setText(mRecipeServings);
    recipeValues.setText(mRecipeValues);

}
}

我注意到RecipeCursorAdapter也引用了商店表，并生成错误。

    05-26 17:51:33.218 3468-3468/com.example.android.businessplatform E/com.example.android.businessplatform.RecipeCursorAdapter: Number of Columns 7
    This is the Cursor Location -1
05-26 17:51:33.218 3468-3468/com.example.android.businessplatform E/CursorWindow: Failed to read row 0, column -1 from a CursorWindow which has 2 rows, 7 columns.
05-26 17:51:33.220 3468-3468/com.example.android.businessplatform E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android.businessplatform, PID: 3468
    java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
        at android.database.CursorWindow.nativeGetString(Native Method)
        at android.database.CursorWindow.getString(CursorWindow.java:438)
        at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
        at android.database.CursorWrapper.getString(CursorWrapper.java:137)
        at com.example.android.businessplatform.RecipeCursorAdapter.bindView(RecipeCursorAdapter.java:37)
        at android.widget.CursorAdapter.getView(CursorAdapter.java:289)
        at android.widget.AbsListView.obtainView(AbsListView.java:2413)
        at android.widget.ListView.measureHeightOfChildren(ListView.java:1331)
        at android.widget.ListView.onMeasure(ListView.java:1238)
        at android.view.View.measure(View.java:19937)
        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
        at android.view.View.measure(View.java:19937)
        at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1059)
        at android.view.View.measure(View.java:19937)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1632)
        at android.view.View.measure(View.java:19937)
        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
        at android.view.View.measure(View.java:19937)
        at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1059)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6139)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:141)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6139)
        at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:400)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6139)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6139)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1489)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:775)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:657)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6139)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at com.android.internal.policy.DecorView.onMeasure(DecorView.java:729)
        at android.view.View.measure(View.java:19937)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2442)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1488)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1747)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1372)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6782)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:933)
        at android.view.Choreographer.doCallbacks(Choreographer.java:742)
        at android.view.Choreographer.doFrame(Choreographer.java:674)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:919)
        at android.os.Handler.handleCallback(Handler.java:761)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:156)
        at android.app.ActivityThread.main(ActivityThread.java:6623)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:832)

Answer 1

消息： -

05-26 17:51:33.218 3468-3468/com.example.android.businessplatform E/CursorWindow: Failed to read row 0, column -1 from a CursorWindow which has 2 rows, 7 columns.

说光标中偏移-1处没有列有2行7列的列。因此，偏移0-6将与光标中的列相关联。

您收到 -1 ，因为当指定的列不是Cursor中的某列时，getColumnIndex方法返回 -1 。

e.g。如果您有一个包含列col1，col2的表，并且您运行了一个创建Cursor c的查询，那么： -

c.getColumnIndex("col1")将返回0的offfset。 c.getColumnIndex("col2")将返回1的offf。

虽然没有名为 col3 的列，但c.getColumnIndex("col3")会返回-1的offfset。

究竟为什么列名不存在不能仅仅从适配器确定，因为可能的问题是传递给适配器的光标和适配器中访问的列的组合。因此，需要用于调用适配器的代码来确定原因。

因此，您需要检查传递给adpaters的Cursor是否包含预期的列。您可以使用适配器的DatabaseUtils.dumpCurrentRow方法中的bindView方法，然后检查输出到日志来执行此操作。

这是一个两个片段的基本示例，每个片段都有一个列表（StoreEntry和RecipeeEntry），但是基于你的一些代码。

它有一个 StoreEntry 类： -

public class StoreEntry {
    public static final String TBNAME = "store_entry";
    public static final String COLUMN_PRODUCT_NAME = "product_name";
    public static final String COLUMN_PRODUCT_PRICE = "product_price";
    public static final String COLUMN_PRODUCT_QUANTITY = "product_quantity";
    public static final String COLUMN_PRODUCT_WEIGHT = "product_weight";
    public static final String COLUMN_SUPPLIER_NAME = "supplier_name";
    public static final String COLUMN_SUPPLIER_NUMBER = "supplier_number";
}

和 RecipeeEntry 类为： -

public class RecipeeEntry {
    public static final String COLUMN_RECIPEE_SERVINGS = "recipee_servings";
    public static final String COLUMN_RECIPEE_NAME = "recipee_name";
    public static final String COLUMN_RECIPEE_TYPE = "recipee_type";
    public static final String COLUMN_RECIPEE_VALUES = "recipee_values";
}

数据库助手类 DBHelper ： -

public class DBHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "mydatabase";
    public static final int DBVERSION = 1;

    public static final String TBSTORE = "store";
    public static final String TBRECIPEE = "recipee";

    private static final String store_crt = "CREATE TABLE IF NOT EXISTS " +
            TBSTORE + "(" +
            BaseColumns._ID + " INTEGER PRIMARY KEY, " +
            StoreEntry.COLUMN_PRODUCT_NAME + " TEXT, " +
            StoreEntry.COLUMN_PRODUCT_PRICE + " REAL, " +
            StoreEntry.COLUMN_PRODUCT_QUANTITY + " INTEGER, " +
            StoreEntry.COLUMN_PRODUCT_WEIGHT + " INTEGER, " +
            StoreEntry.COLUMN_SUPPLIER_NAME + " TEXT, " +
            StoreEntry.COLUMN_SUPPLIER_NUMBER + " INTEGER" +
            ")";

    private static final String recipee_crt = "CREATE TABLE IF NOT EXISTS " +
            TBRECIPEE + "(" +
            BaseColumns._ID + " INTEGER PRIMARY KEY, " +
            RecipeeEntry.COLUMN_RECIPEE_NAME + " TEXT, " +
            RecipeeEntry.COLUMN_RECIPEE_TYPE + " TEXT, " +
            RecipeeEntry.COLUMN_RECIPEE_SERVINGS + " INTEGER, " +
            RecipeeEntry.COLUMN_RECIPEE_VALUES + " TEXT " +
            ")";

    SQLiteDatabase mDB;


    public DBHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        mDB = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(store_crt);
        db.execSQL(recipee_crt);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int i, int i1) {

    }

    public long addStore(String product_name,
                         Float product_price,
                         int product_quantity,
                         int product_weight,
                         String supplier_name,
                         int supplier_number) {

        ContentValues cv = new ContentValues();
        cv.put(StoreEntry.COLUMN_PRODUCT_NAME,product_name);
        cv.put(StoreEntry.COLUMN_PRODUCT_PRICE,product_price);
        cv.put(StoreEntry.COLUMN_PRODUCT_QUANTITY,product_quantity);
        cv.put(StoreEntry.COLUMN_PRODUCT_WEIGHT,product_weight);
        cv.put(StoreEntry.COLUMN_SUPPLIER_NAME,supplier_name);
        cv.put(StoreEntry.COLUMN_SUPPLIER_NUMBER,supplier_number);
        return mDB.insert(TBSTORE,null,cv);
    }

    public Cursor getStoreEntries() {
        return mDB.query(TBSTORE,null,null,null,null,null,null);
    }

    public long addRecipee(String recipee_name, String recipee_type,int recipee_servings, String recipee_values) {
        ContentValues cv = new ContentValues();
        cv.put(RecipeeEntry.COLUMN_RECIPEE_NAME, recipee_name);
        cv.put(RecipeeEntry.COLUMN_RECIPEE_TYPE,recipee_type);
        cv.put(RecipeeEntry.COLUMN_RECIPEE_SERVINGS,recipee_servings);
        cv.put(RecipeeEntry.COLUMN_RECIPEE_VALUES,recipee_values);
        return mDB.insert(TBRECIPEE,null,cv);
    }

    public Cursor getRecipeeEntries() {
        return mDB.query(TBRECIPEE,null,null,null,null,null,null);
    }
}

一个非常基本的MainActivity，如果不存在则会添加一些数据： -

public class MainActivity extends AppCompatActivity
    implements
        StoreEntryFragment.OnFragmentInteractionListener,
        RecipeeEntryFragment.OnFragmentInteractionListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DBHelper mDBHlpr = new DBHelper(this);
        if (DatabaseUtils.queryNumEntries(mDBHlpr.getWritableDatabase(),DBHelper.TBSTORE) < 1) {
            mDBHlpr.addStore("Rice",1.53f,10,1000,"The Rice Company",1);
            mDBHlpr.addStore("Bran",2.34f,100,500,"BranDed",25);
        }
        if(DatabaseUtils.queryNumEntries(mDBHlpr.getWritableDatabase(),DBHelper.TBRECIPEE) < 1) {
            mDBHlpr.addRecipee("RiceCrisps","Yucky",10,"This and that");
            mDBHlpr.addRecipee("Bran Flakes","Makes you go",5,"Flakes or something");
        }
    }

    @Override
    public void onFragmentInteraction(Uri uri) {
    }
}

类StoreEntryFragment： -

public class StoreEntryFragment extends Fragment {
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";


    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    DBHelper mDBHlpr;
    Cursor mCsr;
    SimpleCursorAdapter mSCA;
    ListView mStoreList;

    public StoreEntryFragment() {
    }

    public static StoreEntryFragment newInstance(String param1, String param2) {
        StoreEntryFragment fragment = new StoreEntryFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view =  inflater.inflate(R.layout.fragment_store_entry, container, false);
        mStoreList = view.findViewById(R.id.store_entry_listview);
        mDBHlpr = new DBHelper(getActivity());
        mCsr = mDBHlpr.getStoreEntries();
        mSCA = new SimpleCursorAdapter(
                getActivity(),
                android.R.layout.simple_list_item_2,
                mCsr,
                new String[]{StoreEntry.COLUMN_PRODUCT_NAME,StoreEntry.COLUMN_PRODUCT_PRICE},
                new int[]{android.R.id.text1,android.R.id.text2}
        );
        mStoreList.setAdapter(mSCA);

        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

注意onCreateView方法中的代码和事先定义的变量。
这使用带有提供布局的SimpleCursorAdapter。
处理是
1. 根据它的身份获取ListView。
2. 获取DBHelper的实例。
3. 获取此列表的光标。
4. 使用刚刚检索的游标创建SimpleCursorAdapter的实例。
5. 将适配器附加（设置）到ListView。

这里是RecipeeList的等价物（基本相同）： -

public class RecipeeEntryFragment extends Fragment {
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    DBHelper mDBHlpr;
    Cursor mCsr;
    SimpleCursorAdapter mSCA;
    ListView mRecipeeList;


    public RecipeeEntryFragment() {
    }

    public static RecipeeEntryFragment newInstance(String param1, String param2) {
        RecipeeEntryFragment fragment = new RecipeeEntryFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_recipee_entry, container, false);
        mRecipeeList = view.findViewById(R.id.recipee_entry_listview);
        mDBHlpr = new DBHelper(getActivity());
        mCsr = mDBHlpr.getRecipeeEntries();
        Log.d("RECIPEEFRAG","Number of rows in Cursor is " + String.valueOf(mCsr.getCount()));
        mSCA = new SimpleCursorAdapter(
                getActivity(),
                android.R.layout.simple_list_item_2,
                mCsr,
                new String[]{RecipeeEntry.COLUMN_RECIPEE_NAME,RecipeeEntry.COLUMN_RECIPEE_TYPE},
                new int[]{android.R.id.text1, android.R.id.text2}
                );
        mRecipeeList.setAdapter(mSCA);
        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

结果是： -

布局是： -

activity_main.xml ： -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_weight="1"
        android:layout_height="0dp">
        <fragment
            android:name="flv.fragmentlistviews.StoreEntryFragment"
            android:id="@+id/store_entry_fragment"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent">
        </fragment>
        <fragment
            android:name="flv.fragmentlistviews.RecipeeEntryFragment"
            android:id="@+id/recipee_entry_fragment"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent">
        </fragment>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_weight="1"
        android:layout_height="0dp">

    </LinearLayout>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />
</LinearLayout>

fragment_store_entry.xml ： -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".StoreEntryFragment"
    android:background="#AA00FF55">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="10"
        android:text="@string/hello_blank_fragment" />

    <ListView
        android:id="@+id/store_entry_listview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="90"
        android:background="#FF00EE33">
    </ListView>
</LinearLayout>

fragment_recipee_entry.xml ： -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RecipeeEntryFragment"
    android:background="#AA0055FF">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="10"
        android:text="@string/hello_blank_fragment" />
    <ListView
        android:id="@+id/recipee_entry_listview"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="90"
        android:background="#FF0033EE">
    </ListView>
</LinearLayout>

继续前进

从上面开始，介绍适配器的简短步骤（根据问题编写的代码）可以正常工作。

注
- 由于我使用了recipee而不是食谱，因此进行了微小的更改。
- 还修改了StoreEntry和RecipeeEntry以包含_ID和CONTENT_URI常量。

对于 StoreEntryFragment ： -

为PlatformCursorAdapter添加另一个类变量： - PlatformCursorAdapter mPCA;

所以你有： -

DBHelper mDBHlpr;
Cursor mCsr;
SimpleCursorAdapter mSCA;
ListView mStoreList;
PlatformCursorAdapter mPCA; //<<<< ADDED

在行onCreateViewMethod之后的mStoreList.setAdapter(mSCA);和return View之前添加以下两行： -
```
mPCA = new PlatformCursorAdapter(getActivity(),mCsr);
mStoreList.setAdapter(mPCA);
```

对于 RecipeeEntryFragment ，您有： -

    DBHelper mDBHlpr;
    Cursor mCsr;
    SimpleCursorAdapter mSCA;
    ListView mRecipeeList;
    RecipeCursorAdapter mRCA; //<<<< ADDED

和： -

    mRCA = new RecipeCursorAdapter(getActivity(),mCsr);
    mRecipeeList.setAdapter(mRCA);

请注意！使用了以下（非常基本的）布局： -

list_view.xml ： -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/item_name"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/item_price"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/item_quantity"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/item_weight"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/item_supplier_name"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/item_supplier_number"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
</LinearLayout>

recipe_activity.xml： -

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/recipe_name"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/recipe_type"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/recipe_servings"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/ingrediant_name_1"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent" />
</LinearLayout>

结果（仅显示部分屏幕）现在是： -

为颜色道歉，而不是最好的。

Answer 2

好的，最后问题已经解决了，显然我需要在每个CursorAdapter中启动一个DatabaseHelper。

public class RecipeCursorAdapter extends CursorAdapter {

private static final String LOG_TAG = RecipeCursorAdapter.class.getName();

public RecipeCursorAdapter (Context context, Cursor cursor1){
    super(context, cursor1, 0);
}
@Override
public View newView(Context context, Cursor cursor1, ViewGroup parent) {
    return LayoutInflater.from(context).inflate(R.layout.recipe_activity, parent, false);
}

@Override
public void bindView(View view, Context context, Cursor cursor1) {

    DatabaseHelper helper = new DatabaseHelper(context);
    SQLiteDatabase db = helper.getReadableDatabase();
    cursor1 = db.rawQuery("SELECT * FROM " + RecipeEntry.TABLE_NAME_RECIPE, null);

    Log.i(LOG_TAG, "Number of Columns " + cursor1.getColumnCount());
    //find which fields would be populated
    TextView recipeName = view.findViewById(R.id.recipe_name);
    TextView recipeType = view.findViewById(R.id.recipe_type);
    TextView recipeServings = view.findViewById(R.id.recipe_servings);
    TextView recipeValues = view.findViewById(R.id.ingrediant_name_1);
    if(cursor1.moveToNext()) {
        //get the data from the table recipes
        String mRecipeName = cursor1.getString(cursor1.getColumnIndex(RecipeEntry.COLUMN_RECIPE_NAME));
        String mRecipeType = cursor1.getString(cursor1.getColumnIndexOrThrow(RecipeEntry.COLUMN_RECIPE_TYPE));
        String mRecipeServings = cursor1.getString(cursor1.getColumnIndexOrThrow(RecipeEntry.COLUMN_RECIPE_SERVINGS));
        String mRecipeValues = cursor1.getString(cursor1.getColumnIndexOrThrow(RecipeEntry.COLUMN_RECIPE_VALUES));

        //get current item Id
        int currenId = cursor1.getInt(cursor1.getColumnIndex(RecipeEntry._ID));
        //create a content Uri for the current Id
        final Uri contentUri = Uri.withAppendedPath(RecipeEntry.CONTENT_URI, Integer.toString(currenId));

        //populate fields with their respective data
        recipeName.setText(mRecipeName);
        recipeType.setText(mRecipeType);
        recipeServings.setText(mRecipeServings);
        recipeValues.setText(mRecipeValues);

    }
}
}

谢谢大家的支持和时间@MikeT和@pskink

我们可以有多个扩展CursorAdapter的活动

2 个答案:

继续前进