片段中未执行异步任务

Question

I've been googling quite a fair bit to make this work and somehow it doens't for me. What I'm doing is running fragment and when i open it, i wish for it to be populated by data called from the mySQL database into the listview.

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.narutohd.ServiceHandler.ServiceHandler;

import android.app.ListFragment;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class FindPeopleFragment extends ListFragment {

     private ProgressDialog pDialog;

        // URL to get contacts JSON
        private static String url = "REMOVED";

        // JSON Node names
        private static final String TAG_CONTACTS = "products";
        private static final String TAG_ID = "pid";
        private static final String TAG_NAME = "link";

        // contacts JSONArray
        JSONArray contacts = null;
        private List<HashMap<String, String>> contactList;
        private SimpleAdapter adapter;

    public FindPeopleFragment(){}

    public void onActivityCreated(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
            contactList = new ArrayList<HashMap<String, String>>();
            adapter = new SimpleAdapter(getActivity(), contactList,
                R.layout.list_item, new String[] { TAG_ID, TAG_NAME },
                new int[] { R.id.pid, R.id.episode });

            ListView lv = getListView();
            lv.setAdapter(adapter);
            new GetContacts().execute();
            super.onActivityCreated(savedInstanceState);
        }
     private class GetContacts extends AsyncTask<Void, Void, Void> {

            @Override
            protected void onPreExecute() {


            }

            @Override
            protected Void doInBackground(Void... arg0) {
               //Code
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                } else {
                    Log.e("ServiceHandler", "Couldn't get any data from the url");
                }

                return null;
            }

            @Override
            protected void onPostExecute(Void result) {
               //Code
            }

        }

}

That is my code currently, but all it does on loading is nothing, no errors whatsoever. I believe it should be fine because it works well on an activity. I don't see any reason why it should be. An alternative i thought of would be to pass the data onPostExecute into a public variable then populating it using setListAdapter real time (onActivityCreated) as i understand that the reason why it might not work as of now is because the listview is already inflated once the oNActivity is launched.

Would appreciate some help on this!

Sorry as I'm rather new to Java/Android, was wondering if I'm doing it wrong, or is another way to do it possibly running the Async Task from the mainActivity, THEN populating the listview on the fragment then?

I ran the code below to use adapter.notifyDataSetChanged but it didn't work. The GetContacts still doesn't get executed.

I'm pretty sure the problem is at that GetContacts DoinBackground isn't executed. Or it doesn't seem to be as I don't even see my URL showing up (Which should, neither do i see pDialog initiated at all).

Answer 1

I think,you should call "adapter.notifyDataSetChanged();"

This method can dynamically modify the ListView data.

private List<HashMap<String, String>> contactList;
private SimpleAdapter adapter;

public void onActivityCreated(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
    contactList = new ArrayList<HashMap<String, String>>();
    adapter = new SimpleAdapter(getActivity(), contactList,
        R.layout.list_item, new String[] { TAG_ID, TAG_NAME },
        new int[] { R.id.pid, R.id.episode });

    ListView lv = getListView();
    lv.setAdapter(adapter);
    new GetContacts().execute();
    super.onActivityCreated(savedInstanceState);
}


public class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {

    }

    @Override
    protected Void doInBackground(Void... arg0) {
                    //Your code...
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        adapter.notifyDataSetChanged();
    }
}

Answer 2

I don't know it that is all of the code but I guess that you should add a onCreateView. And use a layout with at listview

Answer 3

我自己解决了它，使用onResume更新。