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我正在实现 ListActivity 和 ListFragment 并希望允许用户使用短按和长按 - 简而言之是编辑/显示项目的详细信息，长按以调出带有删除项目选项的上下文菜单. 但是，我似乎无法触发 onCreateContextMenu。onListItemClick 可以正常工作并捕获所有短按或长按。ListFragment 是使用稍微定制的 SimpleCursorAdaptor 和 LoaderManager 填充的，而不是使用布局文件。

有可能两者兼得吗？

代码...

LocationsListFragment.java

package com.level3.connect.locations;

//import removed for brevity

public class LocationsListFragment extends SherlockListFragment implements LoaderManager.LoaderCallbacks<Cursor>{

private static final int DELETE_ID = Menu.FIRST + 1;    

private SimpleCursorAdapter adapter;
private OnLocationSelectedListener locationSelectedListener;

// the activity attaching to this fragment should implement this interface
public interface OnLocationSelectedListener {
    public void onLocationSelected(String locationId);
}    

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    // Fields from the database (projection)
    // Must include the _id column for the adapter to work
    String[] from = new String[] { LocationsTable.LOCATION_NAME, 
            LocationsTable.LOCATION_PHONE_NAME };
    // Fields on the UI to which we map
    int[] to = new int[] { R.id.titleText, R.id.phoneText };

    // connect to the database
    getLoaderManager().initLoader(0, null, this);
    adapter = new LocationCursorAdapter(getActivity(), 
            R.layout.location_row, null, from, to, 0);

    setListAdapter(adapter);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View root = super.onCreateView(inflater, container, savedInstanceState);    
    registerForContextMenu(root); //this is called fine
    return root;
}

// hook up listening for the user selecting a location in the list
@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        locationSelectedListener = (OnLocationSelectedListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnLocationSelectedListener");
    }
}

// handle user tapping a location - show a detailed view - this works fine
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    String projection[] = { LocationsTable.KEY_ID };
    Cursor locationCursor = getActivity().getContentResolver().query(
            Uri.withAppendedPath(DatabaseContentProvider.CONTENT_URI,
                    String.valueOf(id)), projection, null, null, null);
    if (locationCursor.moveToFirst()) {
        String locationUrl = locationCursor.getString(0);
        locationSelectedListener.onLocationSelected(locationUrl);
    }
    locationCursor.close();
}

// Context menu - this is never called
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
        ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    menu.add(0, DELETE_ID, 0, R.string.menu_delete);
}

@Override - this is never called
public boolean onContextItemSelected(android.view.MenuItem item) {
    switch (item.getItemId()) {
    case DELETE_ID:
        AdapterContextMenuInfo info = (AdapterContextMenuInfo) item
                .getMenuInfo();
        Uri uri = Uri.parse(DatabaseContentProvider.CONTENT_URI + "/"
                + info.id);
        getActivity().getContentResolver().delete(uri, null, null);
        return true;
    }
    return super.onContextItemSelected(item);
}

// Loader code
// Creates a new loader after the initLoader () call
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { LocationsTable.KEY_ID, LocationsTable.LOCATION_NAME, LocationsTable.LOCATION_PHONE_NAME };
    CursorLoader cursorLoader = new CursorLoader(getActivity(),
            DatabaseContentProvider.CONTENT_URI, projection, null, null, null);
    return cursorLoader;
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    adapter.swapCursor(data);
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    // data is not available anymore, delete reference
    adapter.swapCursor(null);
}

}

更新：我仍然没有弄清楚这一点，我想知道我是否必须放弃这个策略并以其他方式实施它，而不是用户友好的方式。也许滑动查看详细信息并点击删除？

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1 回答 1

4

我在原生电子邮件应用程序的 Android 源代码中找到了答案。https://android.googlesource.com/platform/packages/apps/Email/

ListFragment 必须实现监听器：

public class MessageListFragment extends SherlockListFragment
    implements LoaderManager.LoaderCallbacks<Cursor>, AdapterView.OnItemLongClickListener

    private static final int DELETE_ID = Menu.FIRST + 1;    

    private SimpleCursorAdapter adapter;

    // The LoaderManager needs initializing
    @Override
    public void onCreate(Bundle savedInstanceState) {

       super.onCreate(savedInstanceState);

       // Fields from the database (projection)
       // Must include the _id column for the adapter to work
       String[] from = new String[] { BookmarksTable.BOOKMARK_NAME, 
            BookmarksTable.BOOKMARK_PHONE_NAME };
       // Fields on the UI to which we map
       int[] to = new int[] { R.id.titleText, R.id.phoneText };

       // connect to the database
       getLoaderManager().initLoader(0, null, this);
       adapter = new BookmarkCursorAdapter(getActivity(), 
            R.layout.bookmark_row, null, from, to, 0);

       setListAdapter(adapter);
    }

    // register to put up the context menu
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
       View root = super.onCreateView(inflater, container, savedInstanceState); 
       registerForContextMenu(root);
       return root;
    }

    // set the listeners for long click
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        getListView().setOnItemLongClickListener(this);
    }

调用的方法有：

 /**
  * Called when a message is clicked.
  */
 @Override
 public void onListItemClick(ListView parent, View view, int position, long id) {
        // do item click stuff; show detailed view in my case

 }


@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
    return false; // let the system show the context menu
  }

// Context menu
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
        ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    menu.add(0, DELETE_ID, 0, R.string.menu_delete);
}

    // respond to the context menu tap
@Override
public boolean onContextItemSelected(android.view.MenuItem item) {
    switch (item.getItemId()) {
    case DELETE_ID:
        AdapterContextMenuInfo info = (AdapterContextMenuInfo) item
                .getMenuInfo();
        Uri uri = Uri.parse(DatabaseContentProvider.BOOKMARK_ID_URI + Long.toString(info.id));
        getActivity().getContentResolver().delete(uri, null, null);
        return true;
    }
    return super.onContextItemSelected(item);
}

为了完整起见，这里是加载器代码

// Loader code
// Creates a new loader after the initLoader () call
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { BookmarksTable.KEY_ID, BookmarksTable.BOOKMARK_NAME, BookmarksTable.BOOKMARK_PHONE_NAME };
    CursorLoader cursorLoader = new CursorLoader(getActivity(),
            DatabaseContentProvider.BOOKMARKS_URI, projection, null, null, null);
    return cursorLoader;
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    adapter.swapCursor(data);
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    // data is not available anymore, delete reference
    adapter.swapCursor(null);
}
于 2013-05-15T17:05:02.053 回答