Android：带有 CursorAdapter 的 ListActivity 即使重新查询也不会更新

Question

我有一个 SearchActivity （扩展 ListActivity）和一个 SearchAdapter 将获取搜索结果。我可以在 logcat 中看到，cursor.getCount() 随着每次点击而增加，cursor.requery() 返回 true，甚至 getListView().getCount() 随着每次搜索结果而增加，但 ListView 保持为空。对于我的适配器中的每个新搜索结果，也会调用更新方法。

我不知道还有什么可能是错误的。这里还有其他人遇到过这样的问题吗？

public class SearchableActivity extends ListActivity implements Observer {

private static final String TAG = "SearchableActivity";
private Context mContext;
private SearchCursorAdapter mSearchAdapter;
private Uri cpUri;
private ListView mListView;
private Runnable updateUI;
private Handler handleRunnable;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.search);
    mContext = this;
    mListView = getListView();
    tvTitle.setText(getString(R.string.search_results));
    cpUri = com.pd.database.MyProvider.CONTENT_URI.buildUpon().appendPath("searchresults").build();
    Cursor cursor = this.managedQuery(cpUri, null, null, null, null);
    mSearchAdapter = new SearchCursorAdapter(mContext, cursor);
    mListView.setAdapter(mSearchAdapter);
    mListView.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Intent podcastDetails = new Intent(getApplicationContext(), MPDetails.class);
            podcastDetails.putExtra("id", id);
            startActivity(pDetails);
        }
    });
    handleRunnable = new Handler();
    updateUI = new Runnable() {

        @Override
        public void run() {
            Log.d(TAG, "in Runnable()");
            Log.d(TAG, "cursor.getCount() beforde: " + String.valueOf(mSearchAdapter.mCursor.getCount()));
            Log.d(TAG, "requery returns: " + String.valueOf(mSearchAdapter.mCursor.requery()));
            Log.d(TAG, "cursor.getCount() after: " + String.valueOf(mSearchAdapter.mCursor.getCount()));
            Log.d(TAG, "count ListViewItems: " + String.valueOf(getListView().getCount()));
            mSearchAdapter.notifyDataSetChanged();
        }
    };
    handleIntent(getIntent());
}

@Override
protected void onNewIntent(Intent intent) {
    setIntent(intent);
    handleIntent(intent);
}

private void handleIntent(Intent intent) {
    if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
        String query = intent.getStringExtra(SearchManager.QUERY);
        searchForPodcasts(query);
    }
}

private void searchForPD(String query) {
    try {
        URL searchURL = new URL(MDirectories.SEARCH+query);
        RSSHandlerSearch searchHandler = new RSSHandlerSearch(mContext, cpUri);
        searchHandler.addObserver(this);
        UrlHandlerBar stuff = new UrlHandlerBar(mContext, searchURL, searchHandler, mProgressbar, cpUri, this);
        new NetworkData().execute(stuff);
    } catch (MalformedURLException e) {}
}

@Override
public void update(Observable observable, Object data) {
    handleRunnable.post(updateUI);
}

}

Answer 1

我遇到了这个问题并修复了它。关键是检查 getReadableDatabase()、getWritableDatabase() 和 close() 调用。请记住，根据文档， getReadableDatabase() 返回的数据库对象“在调用 getWritableDatabase() 或 close() 之前一直有效”。

Answer 2

恕我直言，缺少 setListAdapter( mSearchAdapter )

您应该将其添加到 onCreate 的末尾

Answer 3

我在刷新空 ListView 状态时遇到了类似的问题。

这对我很有帮助：

                if( myAdapter.getCount() == 0 ) {
                    myAdapter.changeCursor(newCursor);
                    myAdapter.notifyDataSetChanged();
                }

我简单地添加了仅当 listView 为空时才更改光标的代码。

希望这会有所帮助。