SimpleCursorAdapter列表不显示

Question

我的SimpleCursorAdapter不会显示我传入其中的ArrayList中的任何数据！为什么这样，我该如何解决？

这是我的ListFragment，你可以看到onViewCreated（）方法中使用的SimpleCursorAdapter。

public class CourseListFragment extends SherlockListFragment {

SQLiteDatabase db;
DbHelper dbHelper;

private static String courseName;
ArrayList<String> courseItems;
SimpleCursorAdapter adapter;
/**
 * The serialization (saved instance state) Bundle key representing the
 * activated item position. Only used on tablets.
 */
private static final String STATE_ACTIVATED_POSITION = "activated_position";

/**
 * The fragment's current callback object, which is notified of list item
 * clicks.
 */
private Callbacks mCallbacks = sDummyCallbacks;

/**
 * The current activated item position. Only used on tablets.
 */
private int mActivatedPosition = ListView.INVALID_POSITION;

/**
 * A callback interface that all activities containing this fragment must
 * implement. This mechanism allows activities to be notified of item
 * selections.
 */
public interface Callbacks {
    /**
     * Callback for when an item has been selected.
     */
    public void onItemSelected(String id);
}

/**
 * A dummy implementation of the {@link Callbacks} interface that does
 * nothing. Used only when this fragment is not attached to an activity.
 */
private static Callbacks sDummyCallbacks = new Callbacks() {
    @Override
    public void onItemSelected(String id) {
    }
};

/**
 * Mandatory empty constructor for the fragment manager to instantiate the
 * fragment (e.g. upon screen orientation changes).
 */
public CourseListFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    // Restore the previously serialized activated item position.
    if (savedInstanceState != null
            && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
        setActivatedPosition(savedInstanceState
                .getInt(STATE_ACTIVATED_POSITION));
    }
    dbHelper = new DbHelper(getActivity());
    db = dbHelper.getWritableDatabase();
    courseItems = new ArrayList<String>();
    String[] projection = new String[] {DbHelper.COURSE_NAME, DbHelper.C_ID};
    String[] from = new String[] { DbHelper.COURSE_NAME };
    Cursor cursor = db.query(DbHelper.TABLE_NAME, projection, null, null, null, null, null);
    // Fields on the UI to which we map
    int[] to = new int[] { getListView().getId() };
    int layout = (Build.VERSION.SDK_INT >= 11) ? android.R.layout.simple_list_item_activated_1
            : android.R.layout.simple_list_item_1;
    adapter = new SimpleCursorAdapter(getActivity(), layout, cursor, from, to, SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
    setListAdapter(adapter);
    // The problem starts here
    SwipeDismissListViewTouchListener touchListener = new SwipeDismissListViewTouchListener(
            getListView(),
            new SwipeDismissListViewTouchListener.OnDismissCallback() {
                public void onDismiss(ListView listView,
                        int[] reverseSortedPositions) {
                    for (int position : reverseSortedPositions) {
                        removeCourse(position);
                        adapter.notifyDataSetChanged();
                    }
                }
            });
    getListView().setOnTouchListener(touchListener);
    getListView().setOnScrollListener(touchListener.makeScrollListener());
    adapter.notifyDataSetChanged();
}

@Override
public void onViewStateRestored(Bundle savedInstanceState) {
    super.onViewStateRestored(savedInstanceState);
    String[] projection = { DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToFirst();

    while (c.moveToNext()) {
        courseName = c.getString(c.getColumnIndex(DbHelper.COURSE_NAME));
        courseItems.add(courseName);
    }
    c.close();
    adapter.notifyDataSetChanged();
}

public void addCourse() {
    String[] projection = { DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToLast();
    courseName = c.getString(c.getColumnIndex(DbHelper.COURSE_NAME));
    courseItems.add(courseName);
    c.close();
    adapter.notifyDataSetChanged();
}

public void removeCourse(int position) {
    String[] projection = { DbHelper.C_ID, DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToPosition(position);
    db.delete(DbHelper.TABLE_NAME, DbHelper.C_ID + "=" + position,
            null);
    c.close();
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);

    // Activities containing this fragment must implement its callbacks.
    if (!(activity instanceof Callbacks)) {
        throw new IllegalStateException(
                "Activity must implement fragment's callbacks.");
    }

    mCallbacks = (Callbacks) activity;
}

@Override
public void onDetach() {
    super.onDetach();

    // Reset the active callbacks interface to the dummy implementation.
    mCallbacks = sDummyCallbacks;
}

@Override
public void onListItemClick(ListView listView, View view, int position,
        long id) {
    super.onListItemClick(listView, view, position, id);
    // Notify the active callbacks interface (the activity, if the
    // fragment is attached to one) that an item has been selected.
    mCallbacks.onItemSelected(null);

}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    if (mActivatedPosition != ListView.INVALID_POSITION) {
        // Serialize and persist the activated item position.
        outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
    }
}

/**
 * Turns on activate-on-click mode. When this mode is on, list items will be
 * given the 'activated' state when touched.
 */
public void setActivateOnItemClick(boolean activateOnItemClick) {
    // When setting CHOICE_MODE_SINGLE, ListView will automatically
    // give items the 'activated' state when touched.
    getListView().setChoiceMode(
            activateOnItemClick ? ListView.CHOICE_MODE_SINGLE
                    : ListView.CHOICE_MODE_NONE);
}

public void setActivatedPosition(int position) {
    if (position == ListView.INVALID_POSITION) {
        getListView().setItemChecked(mActivatedPosition, false);
    } else {
        getListView().setItemChecked(position, true);
    }

    mActivatedPosition = position;
}
}

谢谢！非常感谢！

* 编辑：使用SimpleCursorAdapter更新代码 *

public class CourseListFragment extends SherlockListFragment {

SQLiteDatabase db;
DbHelper dbHelper;

private static String courseName;
ArrayList<String> courseItems;
SimpleCursorAdapter adapter;
/**
 * The serialization (saved instance state) Bundle key representing the
 * activated item position. Only used on tablets.
 */
private static final String STATE_ACTIVATED_POSITION = "activated_position";

/**
 * The fragment's current callback object, which is notified of list item
 * clicks.
 */
private Callbacks mCallbacks = sDummyCallbacks;

/**
 * The current activated item position. Only used on tablets.
 */
private int mActivatedPosition = ListView.INVALID_POSITION;

/**
 * A callback interface that all activities containing this fragment must
 * implement. This mechanism allows activities to be notified of item
 * selections.
 */
public interface Callbacks {
    /**
     * Callback for when an item has been selected.
     */
    public void onItemSelected(String id);
}

/**
 * A dummy implementation of the {@link Callbacks} interface that does
 * nothing. Used only when this fragment is not attached to an activity.
 */
private static Callbacks sDummyCallbacks = new Callbacks() {
    @Override
    public void onItemSelected(String id) {
    }
};

/**
 * Mandatory empty constructor for the fragment manager to instantiate the
 * fragment (e.g. upon screen orientation changes).
 */
public CourseListFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    // Restore the previously serialized activated item position.
    if (savedInstanceState != null
            && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
        setActivatedPosition(savedInstanceState
                .getInt(STATE_ACTIVATED_POSITION));
    }
    dbHelper = new DbHelper(getActivity());
    db = dbHelper.getWritableDatabase();
    courseItems = new ArrayList<String>();
    final String[] projection = new String[] {DbHelper.COURSE_NAME, DbHelper.C_ID};
    Cursor cursor = db.query(DbHelper.TABLE_NAME, projection, null, null, null, null, null);
    // Fields on the UI to which we map
    final String[] from = new String[] { DbHelper.COURSE_NAME };
    final int[] to = new int[] { R.id.internalEmpty };
    final int layout = (Build.VERSION.SDK_INT >= 11) ? android.R.layout.simple_list_item_activated_1
            : android.R.layout.simple_list_item_1;
    adapter = new SimpleCursorAdapter(getActivity(), layout, cursor, from, to, SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
    setListAdapter(adapter);
    // The problem starts here
    SwipeDismissListViewTouchListener touchListener = new SwipeDismissListViewTouchListener(
            getListView(),
            new SwipeDismissListViewTouchListener.OnDismissCallback() {
                public void onDismiss(ListView listView,
                        int[] reverseSortedPositions) {
                    for (int position : reverseSortedPositions) {
                        removeCourse(position);
                        Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null, null, null);
                        adapter = new SimpleCursorAdapter(getActivity(), layout, c, from, to, SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
                        setListAdapter(adapter);
                    }
                }
            });
    getListView().setOnTouchListener(touchListener);
    getListView().setOnScrollListener(touchListener.makeScrollListener());
    adapter.notifyDataSetChanged();
}

@Override
public void onViewStateRestored(Bundle savedInstanceState) {
    super.onViewStateRestored(savedInstanceState);
    String[] projection = { DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToFirst();

    while (c.moveToNext()) {
        courseName = c.getString(c.getColumnIndex(DbHelper.COURSE_NAME));
        courseItems.add(courseName);
    }
    c.close();
    adapter.notifyDataSetChanged();
}

public void addCourse() {
    String[] projection = { DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToLast();
    courseName = c.getString(c.getColumnIndex(DbHelper.COURSE_NAME));
    courseItems.add(courseName);
    c.close();
    adapter.notifyDataSetChanged();
}

public void removeCourse(int position) {
    String[] projection = { DbHelper.C_ID, DbHelper.COURSE_NAME };
    Cursor c = db.query(DbHelper.TABLE_NAME, projection, null, null, null,
            null, null);
    c.moveToPosition(position);
    db.delete(DbHelper.TABLE_NAME, DbHelper.C_ID + "=" + position,
            null);
    c.close();
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);

    // Activities containing this fragment must implement its callbacks.
    if (!(activity instanceof Callbacks)) {
        throw new IllegalStateException(
                "Activity must implement fragment's callbacks.");
    }

    mCallbacks = (Callbacks) activity;
}

@Override
public void onDetach() {
    super.onDetach();

    // Reset the active callbacks interface to the dummy implementation.
    mCallbacks = sDummyCallbacks;
}

@Override
public void onListItemClick(ListView listView, View view, int position,
        long id) {
    super.onListItemClick(listView, view, position, id);
    // Notify the active callbacks interface (the activity, if the
    // fragment is attached to one) that an item has been selected.
    mCallbacks.onItemSelected(null);

}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    if (mActivatedPosition != ListView.INVALID_POSITION) {
        // Serialize and persist the activated item position.
        outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
    }
}

/**
 * Turns on activate-on-click mode. When this mode is on, list items will be
 * given the 'activated' state when touched.
 */
public void setActivateOnItemClick(boolean activateOnItemClick) {
    // When setting CHOICE_MODE_SINGLE, ListView will automatically
    // give items the 'activated' state when touched.
    getListView().setChoiceMode(
            activateOnItemClick ? ListView.CHOICE_MODE_SINGLE
                    : ListView.CHOICE_MODE_NONE);
}

public void setActivatedPosition(int position) {
    if (position == ListView.INVALID_POSITION) {
        getListView().setItemChecked(mActivatedPosition, false);
    } else {
        getListView().setItemChecked(position, true);
    }

    mActivatedPosition = position;
}
}

Answer 1

int[] to = new int[] { getListView().getId() };

那条线是错的。我无法想象幕后发生了什么。 int[] to应该是例如

int[] to = new int[] {R.id.text1};

您传递给SimpleCursorAdapter的textView参数中的int layout的ID，您希望将String[] from的列写入。我建议你找出textView id的内容：

int layout = (Build.VERSION.SDK_INT >= 11) ? android.R.layout.simple_list_item_activated_1
            : android.R.layout.simple_list_item_1;

然后就这样做一个条件语句。

---

编辑使用以下行

int[] to = new int[] {android.R.id.text1};