Android：如何在片段

Question

我尝试使用OnActivityCreated调用片段中的其他Activity，我的代码有什么问题。它不起作用。请帮助，谢谢。 提取代码如下所示

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        setContentView(R.layout.activity_main);

        ArrayAdapter<String> adapter = new ArrayAdapter<String> (getActionBar().getThemedContext(), android.R.layout.simple_list_item_1, data);
        FragmentManager fm = getChildFragmentManager();
        fragment = (MapFragment) fm.findFragmentById(R.id.map);
        if (fragment == null) {
            fragment = MapFragment.newInstance();
            fm.beginTransaction().replace(R.id.map, fragment).commit();
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        if (map == null) {
            map = fragment.getMap();
            map.addMarker(new MarkerOptions().position(new LatLng(0, 0)));
        }
    }
}