【问题标题】：Converting a Location to LatLng将位置转换为 LatLng
【发布时间】：2017-12-06 10:58:52
【问题描述】：

我正在尝试在当前位置设置标记，因此我尝试将 Location 转换为 LatLng 类：

LatLng mCurrentPlace= new LatLng(location.getLatitude(),location.getLongitude());

然后我又想起了addMarker方法：

 mMap.addMarker(new MarkerOptions()
    .title(getString(R.string.default_info_title))
    .position(mCurrentPlace)
    .snippet(getString(R.string.default_info_snippet)))

但是通过“运行”启动应用程序，它就停止了。

我哪里出错了？

谢谢。

【问题讨论】：

被捕了？你的意思是它崩溃了？如果是这样，logcat 上的回溯是什么？
被捕了？你什么意思
如果我的回答对您有用，请接受。

标签： android google-maps geolocation

【解决方案1】：

  public void moveMap(GoogleMap gMap, double latitude, double longitude) {
        Log.v(TAG, "mapMoved: " + gMap);
        LatLng latlng = new LatLng(latitude, longitude);
        CameraUpdate cu = CameraUpdateFactory.newLatLngZoom(latlng, 6);
        gMap.addMarker(new MarkerOptions().position(latlng));
        gMap.moveCamera(cu);
    }

在你想要定位和标记的地方调用这个方法，并在 mapasync 回调方法中。

@Override
        public void onMapReady(GoogleMap googleMap) {

            MapsInitializer.initialize(context);
            gMap = googleMap;
            gMap.getUiSettings().setMapToolbarEnabled(false);
            gMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
            if(items.get(getLayoutPosition())!=null )
                moveMap(gMap,latitude, longitude);
        }
        public void initializeMapView() {
            if (mapView != null) {
                // Initialise the MapView
                mapView.onCreate(null);
                // Set the map ready callback to receive the GoogleMap object
                mapView.getMapAsync(this);

            }
        }

重写 onMapReadyCallback 方法并执行此操作。

在onCreate()或适配器onBindViewHolder中调用initializeMapView方法

【讨论】：

【解决方案2】：

尝试使用LatLng.Builder

LatLng.Builder builder = LatLng.newBuilder();
builder.setLatitude(location.getLatitude());
builder.setLongitude(location.getLongitude());
latLng = builder.build();

【讨论】：

【解决方案3】：

地图活动

public class MapsActivity2 extends FragmentActivity implements 
OnMapReadyCallback, GoogleMap.OnMyLocationButtonClickListener {

private GoogleMap mMap;

LatLng loc;
Location location;
private double currentLatitude = 0;
private double currentLongitude = 0;
LocationManager locationManager;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps2);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

}


/**
 * Manipulates the map once available.
 * This callback is triggered when the map is ready to be used.
 * This is where we can add markers or lines, add listeners or atLnmove the camera. In this case,
 * we just add a marker near Sydney, Australia.
            * If Google Play services is not installed on the device, the user will be prompted to install
 * it inside the SupportMapFragment. This method will only be triggered once the user has
 * installed Google Play services and returned to the app.
            */
    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;


        // Add a marker in Sydney and move the camera
//        LatLng sydney = new LatLng(-34, 151);
//        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker 
in Sydney"));
//        mMap.moveCamera(CameraUpdateFactory.newLg(sydney));

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        // TODO: Consider calling
        //    ActivityCompat#requestPermissions
        // here to request the missing permissions, and then overriding
        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
        //                                          int[] grantResults)
        // to handle the case where the user grants the permission. See the documentation
        // for ActivityCompat#requestPermissions for more details.
        return;
    }
    mMap.setMyLocationEnabled(true);
    mMap.setOnMyLocationButtonClickListener(MapsActivity2.this);

}



public double getLatitude(){
    if(location != null){
        currentLatitude = location.getLatitude();
    }
    // return latitude
    return currentLatitude;
}

public double getLongitude(){
    if(location != null){
        currentLongitude = location.getLongitude();
    }
    // return longitude
    return currentLongitude;
}

@Override
public boolean onMyLocationButtonClick() {
    location=mMap.getMyLocation();
    currentLatitude=getLatitude();
    currentLongitude=getLongitude();

    LatLng currentLocation = new LatLng(currentLatitude, currentLongitude);
    mMap.moveCamera(CameraUpdateFactory.newLatLng(currentLocation));
    mMap.addMarker(new MarkerOptions().position(currentLocation).title("Marker in Current Location"));


    return false;
}
}

资源 XML

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.atziant.parashar.gmapsapi.MapsActivity2" />

【讨论】：