Android-如何在地图上设置位置 [英] Android-How to set location in map

问题描述

我有这张地图，我想将位置设置为在Intent Extras中收到的lat lon.我该怎么办?

I have this map and I want to set the location to the lat , lon that I receive in the Intent extras.How can I do it?

public class MapActivity extends AppCompatActivity implements OnMapReadyCallback {
    private SupportMapFragment mMapFragment;
    private GoogleMap mGoogleMap;
    private String lat;
    private String lon;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map);
        lat=getIntent().getStringExtra("lat");
        lon=getIntent().getStringExtra("lon");
        mMapFragment=(SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
        mMapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mGoogleMap=googleMap;


    }
}

推荐答案

将此代码放入onMapReady

double lat = location.getLatitude();
double lng= location.getLongitude();
// set up marker and add
googleMap.addMarker(new MarkerOptions().position(new LatLng(lat , lng))
            .title("Location").icon(BitmapDescriptorFactory
                    .defaultMarker(BitmapDescriptorFactory.HUE_RED)));
// move camera to it
googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(lat, lng), 8));

总是在onMapReady调用后执行所有与地图相关的功能，例如绘制多边形，添加标记，移动相机等，因此googleMap不会是null.请记住，即使每次都为您调用它-在某些情况下，它也可能不会在某些设备上触发，并且每个googleMap.someMethod()调用(例如，在onClick下)都将抛出您NullPointerException.为此做好准备

always do all map-related features like drawing polygons, adding markers, moving camera etc. after onMapReady call, so when googleMap won't be null. And remember that even if it gets called every time for you - in some circulumstances it may not get fired on some device and every googleMap.someMethod() call (e.g. under onClick) will throw you NullPointerException. be prepared for that

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