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我正在实现Two Pane UI。左窗格中的列表视图由加载程序填充。单击列表项目时，右窗格显示有关该项目的详细信息。ListView的performItemClick（）在onLoadFinished（）中调用时会导致IllegalStateException异常
我想设置左窗格中的第一个项目，默认情况下将其选中，并将其细节显示在右侧窗格中。要做到这一点，我试图打电话给我performItemClick()名单这样的：
listView.performItemClick(listView,
ListView.SCROLLBAR_POSITION_DEFAULT,
listView.getItemIdAtPosition(ListView.SCROLLBAR_POSITION_DEFAULT));
我在我的装载机onLoadFinished()方法这样做，因为这是我可以确信的一点是列表视图已经填充。这个方法在UI线程中运行，所以我不期待任何打嗝。但是，我得到一个java.lang.IllegalStateException错误。
我想知道为什么在onLoadFinished()中执行点击操作会导致异常，而列表视图上的其他调用如smoothScrollToPosition()会完成。
从其他SO帖子我可以看到它可以使用Handler()完成。但我不清楚为什么滚动列表可以通过直接调用来完成，但单击一个项目需要通过Handler()发布到消息队列中。我对Android相当陌生，在理解其架构方面存在差距。
下面是完整的代码失败：
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
//Update the adapter
mForecastAdapter.swapCursor(data);
//If there is some item in the list that was selected before then scroll to it
if(lastSelectedIndex != ListView.INVALID_POSITION) {
//Restore to last scrolled position
// Get a reference to the ListView, and attach this adapter to it.
ListView listView = (ListView) getActivity().findViewById(R.id.listview_forecast);
listView.smoothScrollToPosition(lastSelectedIndex);
}
//select the first element if two pane is supported and last state doesn't exist
else if(!mUseTodayLayout) {
ListView listView = (ListView) getActivity().findViewById(R.id.listview_forecast);
listView.performItemClick(listView,
ListView.SCROLLBAR_POSITION_DEFAULT,
listView.getItemIdAtPosition(ListView.SCROLLBAR_POSITION_DEFAULT));
}
}
堆栈跟踪粘贴如下：
java.lang.IllegalStateException: Can not perform this action inside of onLoadFinished
at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1369)
at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1383)
at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:636)
at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:615)
at com.example.android.sunshine.app.MainActivity.onListItemClicked(MainActivity.java:200)
at com.example.android.sunshine.app.ForecastFragment.onLoadFinished(ForecastFragment.java:285)
at com.example.android.sunshine.app.ForecastFragment.onLoadFinished(ForecastFragment.java:46)
at android.support.v4.app.LoaderManagerImpl$LoaderInfo.callOnLoadFinished(LoaderManager.java:427)
at android.support.v4.app.LoaderManagerImpl$LoaderInfo.onLoadComplete(LoaderManager.java:395)
at android.support.v4.content.Loader.deliverResult(Loader.java:104)
at android.support.v4.content.CursorLoader.deliverResult(CursorLoader.java:73)
at android.support.v4.content.CursorLoader.deliverResult(CursorLoader.java:35)
at android.support.v4.content.AsyncTaskLoader.dispatchOnLoadComplete(AsyncTaskLoader.java:223)
at android.support.v4.content.AsyncTaskLoader$LoadTask.onPostExecute(AsyncTaskLoader.java:61)
at android.support.v4.content.ModernAsyncTask.finish(ModernAsyncTask.java:461)
at android.support.v4.content.ModernAsyncTask.access$500(ModernAsyncTask.java:47)
at android.support.v4.content.ModernAsyncTask$InternalHandler.handleMessage(ModernAsyncTask.java:474)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)