android - 从 Activity 添加标记到 fragment 映射

Question

我需要从 MainActivity 向 Android Google map ( fragment )添加标记

这是我的代码；

class Map extends android.app.Fragment implements OnMapReadyCallback


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.activity_mapa, container,false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        MapFragment fragment = (MapFragment)getChildFragmentManager().findFragmentById(R.id.map);
        fragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        LatLng marker = new LatLng(19.33978502, -99.19086277);
        googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(marker, 15));
        googleMap.addMarker(new MarkerOptions().title("Marca de Prueba 1").position(marker));
    }
}

我想从这里添加一个标记:

所有这一切都是因为我想从我的主要 Activity 与我的 map 进行交互，那里有一些按钮和 EditText

主 Activity

public class MainActivityextends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener
{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_side_bar);
    }

    FragmentManager fm = getFragmentManager();
    fm.beginTransaction().replace(R.id.content_frame, new Mapa()).commit();
}

Here is how it looks, already has a mark, but insted of calling it from the map activity i need to set it from the MainActivity

Answer 1

你只需要在 Fragment 中定义一个可以从 Activity 调用的公共(public)方法:

class Mapa extends android.app.Fragment implements OnMapReadyCallback

    GoogleMap mMap;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.activity_mapa, container,false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        MapFragment fragment = (MapFragment)getChildFragmentManager().findFragmentById(R.id.map);
        fragment.getMapAsync(this);
    }

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

    //Added public method to be called from the Activity
    public void placeMarker(String title, double lat, double lon) {
      if (mMap != null) {
        LatLng marker = new LatLng(lat, lon);
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(marker, 15));
        mMap.addMarker(new MarkerOptions().title(title).position(marker));
      }
    }
}

然后，在 Activity 中，保留对 Fragment 的引用，以便您可以调用 placeMarker() 方法:

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

  private Mapa mMapFragment;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_side_bar);
      }

      mMapFragment = new Mapa();
      FragmentManager fm = getFragmentManager();
      fm.beginTransaction().replace(R.id.content_frame, mMapFragment).commit();
  }

  private void placeMarkerInMap(String title, double lat, double lon) {
    if (mMapFragment != null) {
       mMapFragment.placeMarker(title, lat, lon); 
    }
  }
}

然后，当用户填写 EditText 并单击按钮时，您可以在 Activity 中调用 placeMarkerInMap() 方法。

请注意，如果您尝试在 onMapReady() 回调执行之前调用此方法，则不会有有效的 GoogleMap 引用可用于放置标记。如果需要在 Activity 初始启动时放置标记，则需要在 FragmentTransaction 中使用参数。 See here for more details .