我想在MapReady上显示AlertDialogue。我在其他班级实施了警报对话框，并且运行良好。

当我在扩展Fragmentactivity的Mapsactivity中添加警报对话代码时，它无法按预期工作。

当我运行活动时，AlertDialogue确实显示带有按钮。但是标题和消息不显示

public class Mapsactivity extends Fragmentactivity implements GoogleMap.OnCameraIdleListener,OnmapReadyCallback {

    private GoogleMap mMap;
    private Location currentLocation;
    private FusedLocationProviderClient fusedLocationProviderClient;
    private static final int LOCATION_REQUEST_CODE =101;
    private static final String Log_TAG = "Maps_Log_Tag_Results";
    private Context ctx = this;

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

        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
        if (activityCompat.checkSelfPermission(Mapsactivity.this,android.Manifest.permission.accESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && activityCompat.checkSelfPermission(Mapsactivity.this,android.Manifest.permission.accESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            activityCompat.requestPermissions(this,new String[] {android.Manifest.permission.accESS_FINE_LOCATION},LOCATION_REQUEST_CODE);
            return;
        }
        fetchLastLocation();



    }

    private void fetchLastLocation(){
        Task<Location> task = fusedLocationProviderClient.getLastLocation();
        task.addOnSuccessListener(new OnSuccessListener<Location>() {
            @Override
            public void onSuccess(Location location) {
                if (location != null) {
                    currentLocation = location;
                    SupportMapFragment supportMapFragment= (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map1);
                    supportMapFragment.getMapAsync(Mapsactivity.this);
                }else{
                    Toast.makeText(Mapsactivity.this,"No Location recorded",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
    @Override
    public void onmapReady(GoogleMap googleMap) {

        mMap = googleMap;

        mMap.setOnmyLocationButtonClicklistener(onmyLocationButtonClicklistener);
        mMap.setOnmyLocationClicklistener(onmyLocationClicklistener);

        mMap.getUiSettings().setzoomControlsEnabled(true);
        mMap.getUiSettings().setzoomGesturesEnabled(true);
        mMap.setMyLocationEnabled(true);

        mMap.setOnCameraIdleListener(this);

        LatLng latLng = new LatLng(currentLocation.getLatitude(),currentLocation.getLongitude());

        mMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));
        mMap.animateCamera(CameraUpdateFactory.newLatLngzoom(latLng,13));



        // setup the alert builder
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Hello");
        builder.setMessage("This is alert dialogue");

        // add the buttons
        builder.setPositiveButton("Awesome",null);

        // create and show the alert dialog
        AlertDialog dialog = builder.create();
        dialog.show();

    }
}

我认为这与Fragmentactivity有关，因为在activityCompat的警报对话框中工作正常。