android - performItemClick onLoadFinished 后的第一个 ListView 项

Question

我正在使用 CursorLoader 来填充我的 Fragment 中的 ListView。我想要做的是在 ListView 填充数据后以编程方式选择第一项。

我创建了一个 showFirstItem() 方法，我在其中调用 ListView 上的 performItemClick()。

然后我将 showFirstItem() 放入 onLoadFinished() 回调中，希望它会选择列表中的第一项，但结果我得到了这个错误:“java.lang.IllegalStateException:无法在onLoadFinished”。

我不明白为什么不能在这里完成。我应该在哪里调用 performItemClick()？

public class CustomersFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {

  private static final int URL_LOADER = 0;

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    mRootView = inflater.inflate(R.layout.fragment_customers, container, false);

    customersListView = (ListView) mRootView.findViewById(id.list);     

    loadCustomersList();

    return mRootView;
  }

  public void showFirstItem() {
    customersListView.performItemClick(
      mAdapter.getView(0, null, null), 0, mAdapter.getItemId(0)
    );
  }

  private void loadCustomersList() {
    // Initialize loader
    getLoaderManager().initLoader(URL_LOADER, null, this);

    String[] fromColumns = {};
    int[] toViews = {};

    mAdapter = new CustomersCursorAdapter(
      getActivity(), 
      R.layout.list_item_customers, 
      null, 
      fromColumns, 
      toViews
    );

    customersListView.setAdapter(mAdapter);
  }

  @Override
  public Loader<Cursor> onCreateLoader(int loaderID, Bundle bundle) {
    CursorLoader cursorLoader = new CursorLoader(
      getActivity(), 
      CustomersProvider.CONTENT_URI, 
      null, 
      null, 
      null, 
      null
    );
    return cursorLoader;
  }

  @Override
  public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    mAdapter.swapCursor(data);
    showFirstItem(); // <------------ java.lang.IllegalStateException: Can not perform this action inside of onLoadFinished
  }

  @Override
  public void onLoaderReset(Loader<Cursor> loader) {
    mAdapter.swapCursor(null);
  }

------------ 编辑:错误日志

02-24 08:42:34.803: E/AndroidRuntime(986): FATAL EXCEPTION: main
02-24 08:42:34.803: E/AndroidRuntime(986): java.lang.IllegalStateException: Can not perform this action inside of onLoadFinished
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1322)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1329)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.BackStackRecord.commit(BackStackRecord.java:574)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.MainActivity.onCustomerSelected(MainActivity.java:360)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.customers.CustomersFragment.onItemClickCallback(CustomersFragment.java:95)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.customers.CustomersItemClickListener.onItemClick(CustomersItemClickListener.java:56)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.widget.AdapterView.performItemClick(AdapterView.java:298)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.customers.CustomersFragment.showFirstItem(CustomersFragment.java:133)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.customers.CustomersFragment.onLoadFinished(CustomersFragment.java:203)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.myapp.customers.CustomersFragment.onLoadFinished(CustomersFragment.java:1)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.LoaderManagerImpl$LoaderInfo.callOnLoadFinished(LoaderManager.java:483)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.LoaderManagerImpl$LoaderInfo.onLoadComplete(LoaderManager.java:451)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.content.Loader.deliverResult(Loader.java:143)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.content.CursorLoader.deliverResult(CursorLoader.java:113)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.content.CursorLoader.deliverResult(CursorLoader.java:43)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.content.AsyncTaskLoader.dispatchOnLoadComplete(AsyncTaskLoader.java:254)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.content.AsyncTaskLoader$LoadTask.onPostExecute(AsyncTaskLoader.java:91)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.os.AsyncTask.finish(AsyncTask.java:631)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.os.AsyncTask.access$600(AsyncTask.java:177)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.os.Handler.dispatchMessage(Handler.java:99)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.os.Looper.loop(Looper.java:137)
02-24 08:42:34.803: E/AndroidRuntime(986):  at android.app.ActivityThread.main(ActivityThread.java:5041)
02-24 08:42:34.803: E/AndroidRuntime(986):  at java.lang.reflect.Method.invokeNative(Native Method)
02-24 08:42:34.803: E/AndroidRuntime(986):  at java.lang.reflect.Method.invoke(Method.java:511)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-24 08:42:34.803: E/AndroidRuntime(986):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-24 08:42:34.803: E/AndroidRuntime(986):  at dalvik.system.NativeStart.main(Native Method)

------------ 编辑:找到解决方法

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
  mAdapter.swapCursor(data);
  patientsListView.post(new Runnable() {
        @Override
        public void run() {
          showFirstItem();
        }    
    });
}

Answer 1

您要做的是先调用 showFirstItem();，然后再调用 mAdapter.swapCursor(data);。