android – 找出OSMdroid中的当前位置

我想找到我当前位置的地图并在我移动时通过在OSMdroid中显示一个图标来更新它.我在给出具体位置纬度和经度以及绘图图标时发现没有问题但是当我给出当前位置纬度和经度时有两个错误.

public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    mResourceProxy = new DefaultResourceProxyImpl(getApplicationContext());
    setContentView(R.layout.main);        
    mMapView = (MapView) this.findViewById(R.id.mapview);
    mMapView.setTileSource(TileSourceFactory.MAPNIK);
    mMapView.setBuiltInZoomControls(true);
    mMapView.setMultiTouchControls(true);        
    mapController = this.mMapView.getController();
    mapController.setZoom(15);

    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    criteria.setAltitudeRequired(false);
    criteria.setBearingRequired(false);
    criteria.setCostAllowed(true);
    criteria.setPowerRequirement(Criteria.POWER_LOW);
    String provider = mLocMgr.getBestProvider(criteria, true);
    Location location = mLocMgr.getLastKnownLocation(provider);
    GeoPoint mypoint = new GeoPoint(location.getLatitude(), location.getLongitude()); // centre map here
    GeoPoint mypointicon = new GeoPoint(location.getLatitude()+1000, location.getLongitude()+1000); // icon goes here
    mapController.setCenter(mypoint);            
    mLocMgr = (LocationManager) getSystemService(LOCATION_SERVICE);
    mLocMgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 100,
            this);        
    ArrayList<OverlayItem> items=new ArrayList<OverlayItem>();
    items.add(new OverlayItem("Here", "Sample Description", mypointicon));
    this.mMyLocationOverlay = new ItemizedIconOverlay<OverlayItem>(items,
            new ItemizedIconOverlay.OnItemGestureListener<OverlayItem>() {
                @Override
                public boolean onItemSingleTapUp(final int index,
                        final OverlayItem item) {
                    Toast.makeText(
                            MapOverLayGiveActivity.this,
                            "Item '" + item.mTitle, Toast.LENGTH_LONG).show();
                    return true; // We 'handled' this event.
                }
                @Override
                public boolean onItemLongPress(final int index,
                        final OverlayItem item) {
                    Toast.makeText(
                            MapOverLayGiveActivity.this, 
                            "Item '" + item.mTitle ,Toast.LENGTH_LONG).show();
                    return false;
                }
            }, mResourceProxy);
    this.mMapView.getOverlays().add(this.mMyLocationOverlay);
    mMapView.invalidate();        
}

错误：
显示java.lang.NullPointerException
了java.lang.RuntimeException

我的代码有什么问题,我该怎么做？谢谢…

解决方法:

要跟踪位置更改,请按如下所示实现LocationListener：

public class MyLocationListener implements LocationListener {

    public void onLocationChanged(Location location) {
        currentLocation = new GeoPoint(location);
        displayMyCurrentLocationOverlay();
    }

    public void onProviderDisabled(String provider) {
    }

    public void onProviderEnabled(String provider) {
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
    }
}

在onCreate方法内：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    locationListener = new MyLocationListener();        
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    if( location != null ) {
        currentLocation = new GeoPoint(location.getLatitude(), location.getLongitude());
    }
}

和displayMyCurrentLocationOverlay方法：

private void displayMyCurrentLocationOverlay() {
    if( currentLocation != null) {
        if( currentLocationOverlay == null ) {
            currentLocationOverlay = new ArrayItemizedOverlay(myLocationMarker);
            myCurrentLocationOverlayItem = new OverlayItem(currentLocation, "My Location", "My Location!");
            currentLocationOverlay.addItem(myCurrentLocationOverlayItem);
            mapView.getOverlays().add(currentLocationOverlay);              
        } else {
            myCurrentLocationOverlayItem.setPoint(currentLocation);
            currentLocationOverlay.requestRedraw();
        }
        mapView.getController().setCenter(currentLocation);
    }       
}

标签：android,osmdroid
来源： https://codeday.me/bug/20190726/1538885.html