LoadersAndFragments

This project demonstrates how a call to getTransactionManager...commit() from an onLoadFinished callback blows[1] up with an IllegalStateException. This is correct behaviour as documented in the [API] 2.

The question is, however, what is best practice for addressing this requirement? It is possible to use 'commitAllowingStateLoss' but I have not seen simple documentation covering the practical effects from that. Alternatively, one might design out the fragment replacement by fetching the fragment (possibly from a member variable) and directly access the fragment methods (rather than using arguments).

There are examples of workarounds using handlers within onLoadFinished but there is a question of whether that is simply hiding the issues? Is that fundamentally the same as commitAllowingStateLoss? Dianne has also passed some comments.

The code of interest is as follows within ConstantsBrowser. Replacing commit with commitAllowingStateLoss is the most simple fix.

  public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    adapter.swapCursor(cursor);
    
    Fragment fragment = new DetailsFragment();
    Bundle args = new Bundle();
    args.putString(DetailsFragment.KEY_DETAILS, "Total items: " + cursor.getCount());
    fragment.setArguments(args);
    
    // This will cause an exception
    getFragmentManager().beginTransaction().replace(R.id.main_details, fragment).commit();

[1]: Exception from getFragmentManager().beginTransaction().replace(R.id.main_details, fragment).commit();

02-19 20:46:18.509: ERROR/AndroidRuntime(32431): FATAL EXCEPTION: main
        java.lang.IllegalStateException: Can not perform this action inside of onLoadFinished
        at android.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1322)
        at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1329)
        at android.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
        at android.app.BackStackRecord.commit(BackStackRecord.java:574)
        at com.commonsware.android.loader.ConstantsBrowser.onLoadFinished(ConstantsBrowser.java:118)
        at com.commonsware.android.loader.ConstantsBrowser.onLoadFinished(ConstantsBrowser.java:36)
        at android.app.LoaderManagerImpl$LoaderInfo.callOnLoadFinished(LoaderManager.java:483)
        at android.app.LoaderManagerImpl$LoaderInfo.onLoadComplete(LoaderManager.java:451)
        at android.content.Loader.deliverResult(Loader.java:143)
        at android.content.CursorLoader.deliverResult(CursorLoader.java:113)
        at android.content.CursorLoader.deliverResult(CursorLoader.java:43)
        at android.content.AsyncTaskLoader.dispatchOnLoadComplete(AsyncTaskLoader.java:254)
        at android.content.AsyncTaskLoader$LoadTask.onPostExecute(AsyncTaskLoader.java:91)
        at android.os.AsyncTask.finish(AsyncTask.java:631)
        at android.os.AsyncTask.access$600(AsyncTask.java:177)
        at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5193)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
        at dalvik.system.NativeStart.main(Native Method)