有异步和ListAdapter的问题可以帮忙吗?

时间:2014-02-11 06:51:11

标签: java android json android-listview android-asynctask


    package com.example.simpleasync;

import java.util.ArrayList; import java.util.HashMap; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import android.app.ListActivity; import android.app.ProgressDialog; import android.content.Context; import android.os.AsyncTask; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.SimpleAdapter; public class ProgressTask extends AsyncTask<String, Void, Boolean> { private ProgressDialog dialog; private ListActivity activity; private Context context; ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>(); ListView lv ; private static String url = "http://api.cartperk.com/v1/supportedoperator"; private static final String OPCODE="code"; private static final String OPNAME="name"; public ProgressTask(ListActivity activity) { this.activity = activity; context = activity; dialog = new ProgressDialog(context); } protected void onPreExecute() { this.dialog.setMessage("Progress start"); this.dialog.show(); } @Override protected Boolean doInBackground(final String... args) { JSONParser jParser = new JSONParser(); JSONArray json = jParser.getJSONFromUrl(url); for (int i = 0; i < json.length(); i++) { try { JSONObject c = json.getJSONObject(i); String opcode = c.getString(OPCODE); String opname = c.getString(OPNAME); HashMap<String, String> map = new HashMap<String, String>(); map.put(OPCODE,opcode); map.put(OPNAME,opname); jsonlist.add(map); } catch(JSONException e) { e.printStackTrace(); } return null; } } @Override protected void onPostExecute(final Boolean success) { if (dialog.isShowing()) { dialog.dismiss(); } ListAdapter adapter = new SimpleAdapter(context, jsonlist, R.layout.list_item, new String[] { OPCODE, OPNAME}, new int[] { R.id.opcode, R.id.opname}); setListAdapter(adapter); // select single ListView item lv = getListView(); }

我在setLIstViewAdapter和GetlistView中遇到问题,它显示了一些错误并告诉我创建它的方法.. 并且doInBackground要求返回一个布尔值。可以帮助我清除这些错误 谢谢你们

1 个答案:

答案 0 :(得分:0)

也许你可以试试这个:

package com.example.simpleasync;

import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class ProgressTask extends AsyncTask<String, Void, Void> {
 private ProgressDialog dialog;
 private ListActivity activity;
 private Context context;

 ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();
 ListView lv ;

 private static String url = "http://api.cartperk.com/v1/supportedoperator";

 private static final String OPCODE="code";
 private static final String OPNAME="name";

 public ProgressTask(ListActivity activity) {
     this.activity = activity;
     context = activity;
     dialog = new ProgressDialog(context);
 }

 protected void onPreExecute() {
     this.dialog.setMessage("Progress start");
     this.dialog.show();
 }

@Override
protected Void doInBackground(final String... args) {
    JSONParser jParser = new JSONParser();
    JSONArray json = jParser.getJSONFromUrl(url);

    for (int i = 0; i < json.length(); i++)
    {
        try {
            JSONObject c = json.getJSONObject(i);
            String opcode = c.getString(OPCODE);
            String opname = c.getString(OPNAME);

            HashMap<String, String> map = new HashMap<String, String>();

            map.put(OPCODE,opcode);
            map.put(OPNAME,opname);
            jsonlist.add(map);
        }
        catch(JSONException e)
        {
            e.printStackTrace();
        }
    }

    return null;
}

@Override
protected void onPostExecute(final Boolean success) {
  if (dialog.isShowing()) {
    dialog.dismiss();
  }

  ListAdapter adapter = new SimpleAdapter(context, jsonlist,
        R.layout.list_item, new String[] { OPCODE, OPNAME}, new int[] {
        R.id.opcode, R.id.opname});

  activity.setListAdapter(adapter);

  // select single ListView item
  lv = activity.getListView();
}

您需要使用activity对象setListAdaptergetListView。如果您不希望doInBackground(...)返回Boolean,则可以使用Void并返回空值。