谷歌地图api没有将标记放在好位置

我的代码应该找出用户位置,并在进入应用程序时在地图上放置标记。 我的位置值始终等于null,并且从不接收值。

if (location != null) { lat = (int) (location.getLatitude() * 1E6); longi = (int) (location.getLongitude() * 1E6); GeoPoint ourLocation = new GeoPoint(lat, longi); OverlayItem overlayItem = new OverlayItem(ourLocation, "AYO", "Whats good yo"); CustomPinpoint custom = new CustomPinpoint(d, CampusMap.this); custom.insertPinpoint(overlayItem); overlayList.add(custom); } else { Toast.makeText(CampusMap.this, "Couldn't get provider", Toast.LENGTH_SHORT).show(); } } 

我有一个与我正在研究的GPS RPG有一个相对类似的问题,这里有一些我注意到的事情:

首先,最初可能需要一段时间才能find您的位置,这会导致该问题,因为您只检查该位置是否为空。

在执行任何操作之前,您可能还需要确保实际启用了设备的位置服务:

 private boolean doLocationsCheck(){ if(!checkLocationEnabled()){ final CharSequence[] items = {"Yes", "No"}; AlertDialog.Builder builder = new AlertDialog.Builder(mContext); builder.setCancelable(false); builder.setTitle("Location must be enabled to play this game! Would you like to enable it now?"); builder.setItems(items, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int item) { final int i = item; runOnUiThread(new Runnable() { public void run() { if(i == 0){ Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); startActivity(intent); quit(); } else{ quit(); } } }); } }).show(); AlertDialog alert = builder.create(); return false; } else { return true; } } private boolean checkLocationEnabled(){ LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE); boolean enabled = service.isProviderEnabled(LocationManager.GPS_PROVIDER) || service.isProviderEnabled(LocationManager.NETWORK_PROVIDER); return enabled; } 

在我确定提供商可用后,我设置了这样的连接:

  private void setupLocation() { LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE); LocationListener locationListener = new LocationListener() { public void onLocationChanged(final Location location) { runOnUiThread(new Runnable() { public void run() { mLocation = location; //Log.d(TAG, "Latitude: " + location.getLatitude() + " - Longitude: " + location.getLongitude()); saveLocation(); } }); } public void onStatusChanged(String provider, int status, Bundle extras) {} public void onProviderEnabled(String provider) {} public void onProviderDisabled(String provider) {} }; //Can set to GPS or network, whichever is available locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener); } 

然后,只要位置更新,就会在全局variables中设置该位置,然后将其保存到首选项中。 这样,如果提供程序已启用但需要一段时间来检索位置,则用户仍可继续使用应用程序及其应用程序存储的最后已知位置(不适用于第一次程序运行)。

我知道我在那里遗漏了很多,但我认为这不是必要的,因为它要么是不言自明的,要么已经在之前的答案中解释过了。

干杯〜

  /* * getting the best location using the location manager * Constants.MINIMUM_TIME_BETWEEN_UPDATES = 1000 Constants.MINIMUM_TIME_BETWEEN_UPDATES = 1 */ LocationManager mLocation; private String mBestProvider; // in your onCreate() do the following mLocation = (LocationManager) getSystemService(Context.LOCATION_SERVICE); Criteria criteria = new Criteria(); mBestProvider = mLocation.getBestProvider(criteria, false); Location location = mLocation.getLastKnownLocation(mBestProvider); mLocation.requestLocationUpdates( LocationManager.GPS_PROVIDER, Constants.MINIMUM_TIME_BETWEEN_UPDATES, Constants.MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, new LocationListenerManager() ); // and use the following locationListener inner class private class LocationListenerManager implements LocationListener { public void onLocationChanged(Location location) { String message = String.format( "New Location \n Longitude: %1$s \n Latitude: %2$s", location.getLongitude(), location.getLatitude() ); latitude = location.getLatitude(); longitude = location.getLongitude(); Toast.makeText(MapViewActivity.this, message, Toast.LENGTH_LONG).show(); Log.v("poiint=====", ""+message); } public void onStatusChanged(String s, int i, Bundle b) { Toast.makeText(MapViewActivity.this, "Provider status changed", Toast.LENGTH_LONG).show(); } public void onProviderDisabled(String s) { Toast.makeText(MapViewActivity.this, "Provider disabled by the user. GPS turned off", Toast.LENGTH_LONG).show(); } public void onProviderEnabled(String s) { Toast.makeText(MapViewActivity.this, "Provider enabled by the user. GPS turned on", Toast.LENGTH_LONG).show(); } } 

您必须在创建之前初始化onstartActivity中的locationlistener,以便它在onCreate之前获取位置值。