Question

我有一个主活动和一个ListFragment，它包含一个自定义ArrayAdapter，它是该主要活动的一个标签。主要活动有一个AsyncTask，它会下拉一个xml文件，然后在应用程序启动时调用另一个类来解析它。 ListFragment数据来自AsyncTask的解析数据。我希望能够调用ListFragment的自定义适配器，以便我可以在AsyncTask的onPostExecute方法中notifyDataSetChanged。我怎么能做到这一点？

现在，当我打开应用程序时，数据会被拉出并解析，但ListView是空的，因为在AyncTask完成后没有调用notifyDataSetChanged。

代码发布如下：

MainActivity

public class MainActivity extends ActionBarActivity {
    private static final String TAG = MainActivity.class.getSimpleName();

    private ActionBar.Tab tab1, tab2;

    private Fragment fragmentChannels = new ChannelListFragment();
    private Fragment fragmentTab2 = new ChannelListFragment();

    private ArrayList<Channel> mChannels;
    private ArrayList<Programme> mProgrammes;
    private ProgressDialog mProgressDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ActionBar actionBar = getSupportActionBar();
        actionBar.setTitle(R.string.app_name);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        actionBar.addTab(actionBar.newTab().setText(R.string.channels_title).setTabListener(new TabListener(fragmentChannels)));
        actionBar.addTab(actionBar.newTab().setText("tab 2").setTabListener(new TabListener(fragmentTab2)));

        // Get singleton
        mChannels = ChannelStore.get(getApplicationContext()).getChannels();
        // Populate singleton
        populateChannels();
    }

    private void populateChannels() {
        if (CheckNetwork.isInternetAvailable(getApplication())) {
            ChannelSetup cs = new ChannelSetup();
            cs.execute();
        } else {
            Toast.makeText(getApplication(), "No internet connection!", Toast.LENGTH_LONG).show();
        }
    }

    private class ChannelSetup extends AsyncTask<Void, String, String> {

        @Override
        protected String doInBackground(Void... params) {
            // download xml file
        }

        @Override
        protected void onPostExecute(String result) {
            try {
            // parse the xml file and create objects from it.

            // need to update the listadapter of the listfragment somehow
        }
     }
}

ChannelListFragment

public class ChannelListFragment extends ListFragment {
    private static final String TAG = "ChannelListFragment";

    private ArrayList<Channel> mChannels;
    private ChannelAdapter mAdapter;
    private Date mNow;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getActivity().setTitle(R.string.channels_title);
        mNow = new Date();

        mChannels = ChannelStore.get(getActivity()).getChannels();
        Log.i(TAG, "" + mChannels.size() + " " + "");

        mAdapter = new ChannelAdapter(mChannels);
        setListAdapter(mAdapter);
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        Channel c = (Channel) (getListAdapter()).getItem(position);
        Log.i(TAG, "CH" + c.getId() + " clicked");

        Intent i = new Intent(getActivity(), ChannelDetailsActivity.class);
        i.putExtra(ChannelDetailsFragment.EXTRA_CHANNEL_ID, c.getId());
        startActivity(i);
    }

    public class ChannelAdapter extends ArrayAdapter<Channel> {
        public ChannelAdapter(ArrayList<Channel> channels) {
            super(getActivity(), 0, channels);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // If we weren't given a view, inflate one
            if (convertView == null) {
                convertView = getActivity().getLayoutInflater().inflate(
                        R.layout.list_item_channel_table, null);
            }

            // do stuff with various text views, etc

            return convertView;
        }

        public void updateListData() {
            this.clear();
            this.addAll(mChannels);
            this.notifyDataSetChanged();
        }
    }

 }

Answer 1

我建议您在refreshChannels()中创建公共方法ChannelListFragment，以更新ChannelAdapter内容（从ChannelStore获取频道）并在{{1}之后调用}}。您可以在AsyncTask notifyDataSetChanged()方法上调用此方法。

从另一个Activity调用自定义ArrayAdapter方法

1 个答案: