问调用initLoader()后加载器不启动吗？

EN

public class MyFragment extends Fragment {

    public void onActivityCreated() {
        super.onActivityCreated();

        Button btn = ...;
        btn.setOnClickListener(new OnClickListener() {
            public void onClick(View view) {
                getLoaderManager().initLoader(500, null, mMyCallback);
            }
        });
    }  

    private LoaderManager.LoaderCallbacks<String> mMyCallback = new  LoaderManager.LoaderCallbacks<String>() {

        @Override
        public Loader<String> onCreateLoader(int arg0, Bundle arg1) {
            Log.e(TAG, "LoaderCallback.onCreateLoader().");
            return new MyLoader(getActivity());
        }
    }
}

public class MyLoader extends AsyncTaskLoader<String> {
    public MyLoader(Context context) {
        super(context);
    }

    @Override
    public String loadInBackground() {
        Log.e(TAG, "Hi, running.");
        return "terrific.";
    }
}