美好的一天,我正在尝试通过异步任务显示 ListView ,但在显示的 ListView 中取得的成功有限。情况是这样的,我有一个已经显示的 Activity ,当用户按下按钮时,它开始执行 gps Activity 以通过异步任务获取用户位置。现在我想显示一个包含地理编码器结果的 ListView ,以便用户可以选择他想要的位置,然后它会更新回 Activity 中的 TextView 。无法显示此 ListView 。它根本不显示。
相关代码如下:
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.view_location);
}
异步任务类:
class locationTask extends AsyncTask<Object, Void, List<Address> > {
List<Address> addresses;
ProgressDialog progressDialog;
Activity location_activity;
public locationTask(Activity activity){
location_activity = activity;
}
protected void onPreExecute(){
progressDialog = ProgressDialog.show(LocationViewer.this, "", "Getting GPS information Location here");
}
protected List<Address> doInBackground(Object... params){
Log.d(TAG, "am in doinbackground now");
addresses = doGeoCode(globalLocation);
int count = addresses.size();
Log.d(TAG, "count in doinbackground = " + count);
Log.d(TAG, "am out of doinbackground now");
return null;
}
@Override
protected void onPostExecute(List<Address> address){
progressDialog.dismiss();
int count = addresses.size();
Log.d(TAG, "count = " + count);
Log.d(TAG, "am in PostExecute now");
locationAdapter adapter = new locationAdapter(LocationViewer.this, android.R.layout.simple_list_item_1, addresses);
adapter.notifyDataSetChanged();
list.setAdapter(adapter);
}
}
doGeocode 方法:
public List<Address> doGeoCode(Location location){
globalLocation = location;
double newlatitude = globalLocation.getLatitude();
double newlongitude =globalLocation.getLongitude();
Geocoder geocode = new Geocoder(this, Locale.getDefault());
try{
addresses = geocode.getFromLocation(newlatitude, newlongitude, 1);
} catch(IOException e){}
return addresses;
//return addresses;
}
适配器类:
class locationAdapter extends ArrayAdapter<Address> {
Context mycontext;
public locationAdapter(Context context,int textViewResourceId, List<Address> addresses) {
super(context,textViewResourceId, addresses);
mycontext = context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent){
/*View row = convertView;
if(row == null){
LayoutInflater inflater = getLayoutInflater();
row = inflater.inflate(R.layout.view_list, parent, false);
}*/
int maxAddressLineIndex = getItem(position).getMaxAddressLineIndex();
String addressline = "";
for(int j=0; j <= maxAddressLineIndex; j++){
addressline += getItem(position).getAddressLine(j) + ",";
}
TextView rowAddress = new TextView(mycontext);
rowAddress.setText(addressline);
return rowAddress;
}
}
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
StringBuilder sb = new StringBuilder();
sb.append(((Address)parent.getItemAtPosition(position)).getAddressLine(position)).append(",");
sb.append(((Address)parent.getItemAtPosition(position)).getAdminArea()).append(";");
sb.append(((Address)parent.getItemAtPosition(position)).getPostalCode()).append(";");
sb.append(((Address)parent.getItemAtPosition(position)).getCountryName());
address = sb.toString();
}
日志:
11-18 11:47:18.538: VERBOSE/LocationManagerService(1350): requestLocationUpdates
11-18 11:47:18.548: DEBUG/WifiService(1350): enable and start wifi due to updateWifiState
11-18 11:47:18.588: INFO/System.out(1459): [INFO:467227473]: LogSource: Running flush
11-18 11:47:18.588: INFO/System.out(1459): [INFO:467227475]: LogSource: Sending payload [bytes=247]
11-18 11:47:18.648: INFO/System.out(1459): [INFO:467227537]: LogSource: Response [http=200,length=219]
11-18 11:47:18.648: INFO/System.out(1459): [INFO:467227538]: LogSource: Read id 119, status code 200
11-18 11:47:18.688: DEBUG/InputManagerService(1350): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@408a9630
11-18 11:47:18.858: DEBUG/SurfaceFlinger(1350): layer=0xb8fdb8 is not in the purgatory list
11-1811:47:19.529: INFO/wpa_supplicant(1548): got scan complete
11-18 11:47:19.529: INFO/wpa_supplicant(1548): wpa_supplicant_get_scan_results:return scan results2
11-18 11:47:19.529: INFO/wpa_supplicant(1548): AP:ssid[ICYSPICY],rssi[-53],BSSID=00:1c:df:73:b2:6c
11-18 11:47:19.529: INFO/wpa_supplicant(1548): AP:ssid[virginmedia2196134],rssi[-91],BSSID=c4:3d:c7:41:12:f3
11-18 11:47:19.529: INFO/wpa_supplicant(1548): AP:ssid[ICYSPICY],rssi[-85],BSSID=00:24:b2:b4:8b:f8
11-18 11:47:19.529: INFO/wpa_supplicant(1548): Received 950 bytes of scan results (3 BSSes)
11-18 11:47:19.529: INFO/wpa_supplicant(1548): wpa_driver_wext_get_scan_results---
11-18 11:47:19.549: DEBUG/GpsLocationProvider(1350): GetGpsInterface+
11-18 11:47:19.549: DEBUG/GpsLocationProvider(1350): GetGpsInterface-
11-18 11:47:19.549: DEBUG/lib_locapi(1350): loc_eng_inject_location, accuracy = 56.0
11-18 11:47:19.569: DEBUG/AutoSetting(2277): service - mLocationListener: onLocationChanged() location = Location[mProvider=network,mTime=1321616839556,mInfo=-22.2383714333463.40099234999997,mAccuracy=56.0
11-18 11:47:19.569: DEBUG/AutoSetting(2277): service - handleMessage() incoming message, what:1
11-18 11:47:19.569: DEBUG/AutoSetting(2277): service - mLocationListener: onLocationChanged() location = Location[mProvider=network,mTime=1321616839556,mInfo=-22.2383714333463.40099234999997,mAccuracy=56.0
11-18 11:47:19.569: DEBUG/AutoSetting(2277): Util - isSetupWizardCompleted(): true
11-18 11:47:19.569: DEBUG/AutoSetting(2277): Util - wifi connected
11-18 11:47:19.569: DEBUG/AutoSetting(2277): service - processLocationBundle() distance to current is less than 1000.0m, bypass update
11-18 11:47:19.569: DEBUG/AutoSetting(2277): service - handleMessage() within range1
最佳答案
我刚遇到同样的问题并解决了,实际上你只需要这个:
adapter.notifyDataSetChanged();
并且不需要这个:
runOnUIThread(new Runable(){
@Override
public void run(){
adapter.notifyDataSetChanged();
}
};
AsyncTask 与主 UI 线程配合良好。
关于android - 如何从 asyncTask onPostExecute() android 填充 listView,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8181789/