使用从具有 json 输出的数据库中获取位置标记的应用程序。我可以在 LogCat 中看到 json 输出。当我尝试使用 AsyncTask 通过它自己依赖于数据库中有多少项目来添加这些标记时，我得到了一个 FC。
地图活动：
public class MapsActivity extends Activity {
private MainMapFragement mapFragment;
private HashMap<Marker, EventInfo> eventMarkerMap;
private LatLng mPosition;
Geocoder geocoder;
String bestProvider;
List<Address> user = null;
double lat, lng;
LatLng latLng;
private ProgressDialog pDialog;
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
private static String url_all_products = "http://000100023.host56.com/db_all.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "locations";
private static final String TAG_PID = "id";
private static final String TAG_NAME = "name";
// products JSONArray
JSONArray products = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
ActionBar abs = getActionBar();
abs.setTitle(R.string.activity_title_map);
abs.setDisplayHomeAsUpEnabled(true);
mapFragment = new MainMapFragement();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(R.id.map, mapFragment);
ft.commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
protected void onStart() {
super.onStart();
new LoadAllLocations().execute();
//setUpEventSpots();
setCurrentLocationSpot();
}
private void setCurrentLocationSpot() {
LocationManager lm = (LocationManager) MapsActivity.this.getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
bestProvider = lm.getBestProvider(criteria, false);
Location location = lm.getLastKnownLocation(bestProvider);
if (location == null){
Toast.makeText(MapsActivity.this,"Location Not found",Toast.LENGTH_LONG).show();
}else{
geocoder = new Geocoder(MapsActivity.this);
try {
user = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
lat=(double)user.get(0).getLatitude();
lng=(double)user.get(0).getLongitude();
mPosition = new LatLng(lat, lng);
GoogleMap mGap = ((MapFragment) getFragmentManager()
.findFragmentById(R.id.map)).getMap();
mGap.setMyLocationEnabled(true);
mGap.animateCamera(CameraUpdateFactory.newLatLngZoom(mPosition, 13));
}catch (Exception e) {
e.printStackTrace();
}
}
}
private void setUpEventSpots() {
EventInfo firstEventInfo = new EventInfo(new LatLng(60.39341189999999, 5.322973699999999), "Right now - event", new Date(), null);
//EventInfo secondEventInfo = new EventInfo(new LatLng(51.25, 4.15), "Future Event", new Date(1032, 5, 25), null);
Marker firstMarker = mapFragment.placeMarker(firstEventInfo);
//Marker secondMarker = mapFragment.placeMarker(secondEventInfo);
eventMarkerMap = new HashMap<Marker, EventInfo>();
eventMarkerMap.put(firstMarker, firstEventInfo);
//eventMarkerMap.put(secondMarker, secondEventInfo);
/*mapFragment.getMap().setOnInfoWindowClickListener(new OnInfoWindowClickListener() {
@Override
public void onInfoWindowClick(Marker marker) {
EventInfo eventInfo = eventMarkerMap.get(marker);
Toast.makeText(getBaseContext(),
"The date of " + eventInfo.getName() + " is " + eventInfo.getSomeDate().toLocaleString(),
Toast.LENGTH_LONG).show();
}*
});*/
}
class LoadAllLocations extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
//pDialog = new ProgressDialog(MapsActivity.this);
//pDialog.setMessage("Loading locations. Please wait...");
//pDialog.setIndeterminate(false);
//pDialog.setCancelable(false);
//pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
//HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
//map.put(TAG_PID, id);
//map.put(TAG_NAME, name);
// adding HashList to ArrayList
//productsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
//Intent i = new Intent(getApplicationContext(),
// NewProductActivity.class);
// Closing all previous activities
//i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
//startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
//pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
for (int i = 0; i < products.length(); i++) {
try {
JSONObject c = products.getJSONObject(i);
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
String lat = c.getString("lat");
String lng = c.getString("lng");
Double l1 = latLng.latitude;
Double l2 = latLng.longitude;
l1 = Double.parseDouble(lat);
l2 = Double.parseDouble(lng);
//Log.d("LOGTAG", id);
EventInfo eventInfo = new EventInfo(new LatLng(l1, l2), name, new Date(), null);
Marker mMarker = mapFragment.placeMarker(eventInfo);
eventMarkerMap = new HashMap<Marker, EventInfo>();
eventMarkerMap.put(mMarker, eventInfo);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
}
}
}
日志猫：
11-14 23:01:11.448: E/AndroidRuntime(6593): FATAL EXCEPTION: main
11-14 23:01:11.448: E/AndroidRuntime(6593): Process: com.spxc.nightclubratings, PID: 6593
11-14 23:01:11.448: E/AndroidRuntime(6593): java.lang.NullPointerException
11-14 23:01:11.448: E/AndroidRuntime(6593): at com.spxc.nightclubratings.MapsActivity$LoadAllLocations$1.run(MapsActivity.java:239)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.app.Activity.runOnUiThread(Activity.java:4712)
11-14 23:01:11.448: E/AndroidRuntime(6593): at com.spxc.nightclubratings.MapsActivity$LoadAllLocations.onPostExecute(MapsActivity.java:225)
11-14 23:01:11.448: E/AndroidRuntime(6593): at com.spxc.nightclubratings.MapsActivity$LoadAllLocations.onPostExecute(MapsActivity.java:1)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.os.AsyncTask.finish(AsyncTask.java:632)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.os.AsyncTask.access$600(AsyncTask.java:177)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.os.Handler.dispatchMessage(Handler.java:102)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.os.Looper.loop(Looper.java:137)
11-14 23:01:11.448: E/AndroidRuntime(6593): at android.app.ActivityThread.main(ActivityThread.java:4998)
11-14 23:01:11.448: E/AndroidRuntime(6593): at java.lang.reflect.Method.invokeNative(Native Method)
11-14 23:01:11.448: E/AndroidRuntime(6593): at java.lang.reflect.Method.invoke(Method.java:515)
11-14 23:01:11.448: E/AndroidRuntime(6593): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
11-14 23:01:11.448: E/AndroidRuntime(6593): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
11-14 23:01:11.448: E/AndroidRuntime(6593): at dalvik.system.NativeStart.main(Native Method)
为什么我不能让它工作？问题出在如上所示的 onPostExecute 方法中。
任何帮助深表感谢！谢谢