android - 标记聚类在 Android 中不显示标记？

Question

我在 Android 的 PagerFragment 中设置了一个 MapView。我遵循了 Google Example，但使用 V2 API 设置了一个带有集群标记的 map ，它向我显示了一个没有标记的黑色 map 。我哪里出错了？

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);
        }
    }
}

Answer 1

问题是您将错误的上下文传递给集群实例，即 getContext() 应该是 getActivity()。

初始化实例时使用getActivity()

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

当您在 fragment 类中传递上下文时，基本上使用 getActivity

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) {