Marker clustering does not show markers in Android

问题:

I have setup a MapView in a PagerFragment in Android. I followed the Google Example but with V2 API to setup a Map with Clustered markers , it shows a black map to me with no markers. Where did I go wrong ?

import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.LatLng;
import com.google.maps.android.clustering.ClusterManager;

import MapUtils.CustomMarkerItem;

public class TabFragment2 extends Fragment implements OnMapReadyCallback {

    MapView mMapView;
    private GoogleMap googleMap;

    private ClusterManager<CustomMarkerItem> mClusterManager;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.tab_fragment_2, container, false);

        mMapView = (MapView) rootView.findViewById(R.id.mapView);
        mMapView.onCreate(savedInstanceState);

        mMapView.getMapAsync(TabFragment2.this);

        return rootView;
    }

    @Override
    public void onResume() {
        super.onResume();
        mMapView.onResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        mMapView.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mMapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mMapView.onLowMemory();
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        this.googleMap = googleMap;
        if (ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), android.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;
        }
        this.googleMap.setMyLocationEnabled(true);


        setUpClusterer();
    }

    private void setUpClusterer() {
        // Position the map.
        googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(51.503186, -0.126446), 10));

        // Initialize the manager with the context and the map.
        // (Activity extends context, so we can pass 'this' in the constructor.)
        mClusterManager = new ClusterManager<>(getContext(), googleMap);
        googleMap.setOnMarkerClickListener(mClusterManager);
        googleMap.setOnCameraIdleListener(mClusterManager);
        // Add cluster items (markers) to the cluster manager.
        addItems();
    }

    private void addItems() {

        // Set some lat/lng coordinates to start with.
        double lat = 51.5145160;
        double lng = -0.1270060;


        // Set the title and snippet strings.
        String title = "This is the title";
        String snippet = "and this would be it's explaination.";

        // Add ten cluster items in close proximity, for purposes of this example.
        for (int i = 0; i < 10; i++) {
            double offset = i / 60d;
            lat = lat + offset;
            lng = lng + offset;
            CustomMarkerItem offsetItem = new CustomMarkerItem(lat, lng, title, snippet);
            mClusterManager.addItem(offsetItem);
        }
    }
}

回答1:

Problem is that you are passing wrong context to cluster instance ie getContext() which should be getActivity().

Use getActivity() when you initialize the instance

mClusterManager = new ClusterManager<>(getActivity(), googleMap);

and in basically use getActivity when you pass context in fragment class

if (ActivityCompat.checkSelfPermission(getActivity(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

回答2:

@David please this Stackoverflow answer. It might help you to add marker. Or user this code for single marker(can use as per your requirement)

 `Marker marker=`mMap.addMarker(new MarkerOptions().position(latLng).title("Your Location"));
 marker.setIcon(BitmapDescriptorFactory.fromResource(R.drawable.YOUR_IMAGE));//to set any image as marker
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));//for animate camera to your location
  mMap.animateCamera(CameraUpdateFactory.zoomTo(15));//zoom camera to your location

and to cover all your marker (if more then one)

            LatLngBounds.Builder builder = new LatLngBounds.Builder();
        builder.include(startLocation.getLatLng());
        builder.include(endLocation.getLatLng());
        LatLngBounds bounds = builder.build();
        int width = getResources().getDisplayMetrics().widthPixels;
            int height = getResources().getDisplayMetrics().heightPixels;
        mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(bounds, width, width, 20));