java - 尝试创建新标记时 mMap 为 null

Question

所以，一两年后我再次开始这个项目...当它过时时它工作得很好...但是自从 android x 出来我想升级我的应用程序并陷入了我发现的错误很有趣...

简单介绍一下，我有一个按钮可以让我在线/离线。按下按钮后， map 应该按我的当前位置缩放。位置并添加标记..但出现错误:

日志猫:

    Process: com.app.mk.transport, PID: 22142
    java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.model.Marker com.google.android.gms.maps.GoogleMap.addMarker(com.google.android.gms.maps.model.MarkerOptions)' on a null object reference
        at com.app.mk.transport.DriverHome$16$1$1.onComplete(DriverHome.java:1110)
        at com.firebase.geofire.GeoFire$2.onComplete(GeoFire.java:178)
        at com.google.firebase.database.core.Repo$6.run(com.google.firebase:firebase-database@@19.2.0:404)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

DriverHome.java(不是整个代码):

    private void setUpAutocomplete() {

        AutocompleteSupportFragment autocompleteFragment = new AutocompleteSupportFragment();

//        final AutocompleteSupportFragment autocompleteFragment;
//        autocompleteFragment = (AutocompleteSupportFragment) getSupportFragmentManager().findFragmentById(R.id.autocomplete_fragment);

        autocompleteFragment.setCountry("MK");

        if (!Places.isInitialized()) {
            Places.initialize(getApplicationContext(), getResources().getString(R.string.google_open_api));
        }

        autocompleteFragment.setPlaceFields(Arrays.asList(Place.Field.ADDRESS));
        autocompleteFragment.setOnPlaceSelectedListener(new PlaceSelectionListener() {
            @Override
            public void onPlaceSelected(@NonNull Place place) {
                if (location_switch.isChecked()) {

                    destination = place.getAddress();

                    destination = destination.replace(" ", "+");
                    if (destination.contains("+(FYROM)")) {
                        destination = destination.replace("+(FYROM)", "");
                    }
                    mMap.clear();
                    getDirection();
                }
            }

            @Override
            public void onError(@NonNull Status status) {
                Toast.makeText(DriverHome.this, "" + status.toString(), Toast.LENGTH_SHORT).show();
                Log.i("MITKASIN", "An error occurred: " + status);
            }
        });
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.driver_home, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
//         Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_trip_history) {
            // Handle the camera action
        } else if (id == R.id.nav_way_bill) {

        } else if (id == R.id.nav_help) {

        } else if (id == R.id.nav_settings) {

        } else if (id == R.id.nav_update_Info) {

            showDialogUpdateInfo();

        } else if (id == R.id.nav_sign_out) {
            signOut();
        }

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

    private void showDialogUpdateInfo() {
        final AlertDialog.Builder alertDialog = new AlertDialog.Builder(DriverHome.this);
        alertDialog.setTitle("Update Information");
        alertDialog.setMessage("Please fill in the informations");

        LayoutInflater inflater = this.getLayoutInflater();
        View dialog_change_pwd = inflater.inflate(R.layout.layout_update_information, null);

        final TextInputEditText edt_Name = dialog_change_pwd.findViewById(R.id.edtName);
        final TextInputEditText edt_Phone = dialog_change_pwd.findViewById(R.id.edtPhone);
        final ImageView image_upload = (ImageView) dialog_change_pwd.findViewById(R.id.image_upload);

        image_upload.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                chooseImage();
            }
        });

        alertDialog.setView(dialog_change_pwd);

        alertDialog.setPositiveButton("UPDATE", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                final android.app.AlertDialog waitingDialog = new SpotsDialog.Builder()
                        .setContext(DriverHome.this)
                        .setTheme(R.style.Orange)
                        .setMessage(R.string.waitingDialog_title)
                        .setCancelable(false)
                        .build();
                waitingDialog.show();


                AccountKit.getCurrentAccount(new AccountKitCallback<Account>() {
                    @Override
                    public void onSuccess(Account account) {
                        String name = edt_Name.getText().toString();
                        String phone = edt_Phone.getText().toString();

                        Map<String, Object> updateInfo = new HashMap<>();

                        if (!TextUtils.isEmpty(name))
                            updateInfo.put("name", name);

                        if (!TextUtils.isEmpty(phone))
                            updateInfo.put("phone", phone);

                        DatabaseReference driverInformations = FirebaseDatabase.getInstance().getReference(Common.user_driver_tbl);
                        driverInformations.child(account.getId())
                                .updateChildren(updateInfo)
                                .addOnCompleteListener(new OnCompleteListener<Void>() {
                                    @Override
                                    public void onComplete(@NonNull Task<Void> task) {
                                        waitingDialog.dismiss();
                                        if (task.isSuccessful()) {
                                            Toast.makeText(DriverHome.this, "Information updated!", Toast.LENGTH_SHORT).show();
                                        } else {
                                            Toast.makeText(DriverHome.this, "Information update Failed!", Toast.LENGTH_SHORT).show();
                                        }

                                    }
                                });
                    }

                    @Override
                    public void onError(AccountKitError accountKitError) {

                    }
                });

            }
        });

        alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

        alertDialog.show();
    }

    private void chooseImage() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(Intent.createChooser(intent, "Select Picture"), Common.PICK_IMAGE_REQUEST);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == Common.PICK_IMAGE_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
            Uri saveUri = data.getData();
            if (saveUri != null) {
                final ProgressDialog mDialog = new ProgressDialog(this);
                mDialog.setMessage("Uploading...");
                mDialog.show();

                String imageName = UUID.randomUUID().toString();

                final StorageReference imageFolder = storageReference.child("images/" + imageName);
                imageFolder.putFile(saveUri)
                        .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                            @Override
                            public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                                mDialog.dismiss();
                                Toast.makeText(DriverHome.this, "Uploaded !", Toast.LENGTH_SHORT).show();
                                imageFolder.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                                    @Override
                                    public void onSuccess(final Uri uri) {

                                        AccountKit.getCurrentAccount(new AccountKitCallback<Account>() {
                                            @Override
                                            public void onSuccess(Account account) {
                                                Map<String, Object> avatarUpdate = new HashMap<>();
                                                avatarUpdate.put("avatarUrl", uri.toString());

                                                DatabaseReference driverInformations = FirebaseDatabase.getInstance().getReference(Common.user_driver_tbl);
                                                driverInformations.child(account.getId())
                                                        .updateChildren(avatarUpdate)
                                                        .addOnCompleteListener(new OnCompleteListener<Void>() {
                                                            @Override
                                                            public void onComplete(@NonNull Task<Void> task) {
                                                                if (task.isSuccessful()) {
                                                                    Toast.makeText(DriverHome.this, "Uploaded!", Toast.LENGTH_SHORT).show();
                                                                } else {
                                                                    Toast.makeText(DriverHome.this, "Upload error !", Toast.LENGTH_SHORT).show();
                                                                }
                                                            }
                                                        });
                                            }

                                            @Override
                                            public void onError(AccountKitError accountKitError) {

                                            }
                                        });

                                    }
                                });
                            }
                        })
                        .addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
                            @Override
                            public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                                double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                                mDialog.setMessage("Upliaded " + progress + "%");
                            }
                        });
            }
        }
    }

    private void signOut() {
        AlertDialog.Builder builder;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
            builder = new AlertDialog.Builder(this, android.R.style.Theme_Material_Dialog_Alert);
        else
            builder = new AlertDialog.Builder(this);


        builder.setMessage("Do you want to logout?")
                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //        Paper.init(this);

                        AccountKit.logOut();
                        Intent intent = new Intent(DriverHome.this, MainActivity.class);
                        startActivity(intent);
                        finish();
                    }
                })
                .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });

        builder.show();
    }


    private float getBearing(LatLng startPosition, LatLng endPosition) {
        double lat = Math.abs(startPosition.latitude - endPosition.latitude);
        double lng = Math.abs(startPosition.longitude - endPosition.longitude);

        if (startPosition.latitude < endPosition.latitude && startPosition.longitude < endPosition.longitude)
            return (float) (Math.toDegrees(Math.atan(lng / lat)));

        else if (startPosition.latitude >= endPosition.latitude && startPosition.longitude < endPosition.longitude)
            return (float) ((90 - Math.toDegrees(Math.atan(lng / lat))) + 90);

        else if (startPosition.latitude >= endPosition.latitude && startPosition.longitude >= endPosition.longitude)
            return (float) (Math.toDegrees(Math.atan(lng / lat)) + 180);

        else if (startPosition.latitude < endPosition.latitude && startPosition.longitude >= endPosition.longitude)
            return (float) ((90 - Math.toDegrees(Math.atan(lng / lat))) + 270);

        return -1;
    }

    private void updateFirebaseToken() {



        AccountKit.getCurrentAccount(new AccountKitCallback<Account>() {
            @Override
            public void onSuccess(Account account) {

                FirebaseDatabase db = FirebaseDatabase.getInstance();
                DatabaseReference tokens = db.getReference(Common.token_tbl);

                Token token = new Token(FirebaseInstanceId.getInstance().getToken());

                tokens.child(account.getId())
                        .setValue(token);

            }

            @Override
            public void onError(AccountKitError accountKitError) {

            }
        });
    }

    private void getDirection() {
        currentPosition = new LatLng(Common.mLastLocation.getLatitude(), Common.mLastLocation.getLongitude());

        String requestApi = null;
        try {

            requestApi = "https://maps.googleapis.com/maps/api/directions/json?" +
                    "mode=driving&" +
                    "transit_routing_reference=less_driving&" +
                    "origin=" + currentPosition.latitude + "," + currentPosition.longitude + "&" +
                    "destination=" + destination + "&" +
                    "key=" + getResources().getString(R.string.google_direction_api);
            Log.i("MITKASIN", requestApi);
            mServices.getPath(requestApi)
                    .enqueue(new Callback<String>() {
                        @Override
                        public void onResponse(Call<String> call, Response<String> response) {

                            try {
                                JSONObject jsonObject = new JSONObject(response.body());
                                JSONArray jsonArray = jsonObject.getJSONArray("routes");

                                for (int i = 0; i < jsonArray.length(); i++) {

                                    JSONObject route = jsonArray.getJSONObject(i);
                                    JSONObject poly = route.getJSONObject("overview_polyline");
                                    String polyline = poly.getString("points");

                                    polyLineList = decodePoly(polyline);
                                }

                                if (!polyLineList.isEmpty()) {
                                    LatLngBounds.Builder builder = new LatLngBounds.Builder();
                                    for (LatLng latLng : polyLineList)
                                        builder.include(latLng);
                                    LatLngBounds bounds = builder.build();
                                    CameraUpdate mCameraUpdate = CameraUpdateFactory.newLatLngBounds(bounds, 1);
                                    mMap.animateCamera(mCameraUpdate);
//                                    mMap.getUiSettings().setAllGesturesEnabled(true);
                                }
                                polylineOptiuons = new PolylineOptions();
                                polylineOptiuons.color(Color.GRAY);
                                polylineOptiuons.width(5);
                                polylineOptiuons.startCap(new SquareCap());
                                polylineOptiuons.endCap(new SquareCap());
                                polylineOptiuons.jointType(JointType.ROUND);
                                polylineOptiuons.addAll(polyLineList);
                                greyPolyline = mMap.addPolyline(polylineOptiuons);


                                blackPolylineOptions = new PolylineOptions();
                                blackPolylineOptions.color(Color.BLACK);
                                blackPolylineOptions.width(7);
                                blackPolylineOptions.startCap(new SquareCap());
                                blackPolylineOptions.endCap(new SquareCap());
                                blackPolylineOptions.jointType(JointType.ROUND);
                                blackPolyline = mMap.addPolyline(blackPolylineOptions);

                                if (!polyLineList.isEmpty()) {
                                    mMap.addMarker(new MarkerOptions()
                                            .position(polyLineList.get(polyLineList.size() - 1))
                                            .title("Pickup Location"));
                                }
                                //Animation
                                ValueAnimator polyLineAnimator = ValueAnimator.ofInt(0, 100);
                                polyLineAnimator.setDuration(2000);
                                polyLineAnimator.setInterpolator(new LinearInterpolator());
                                polyLineAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                                    @Override
                                    public void onAnimationUpdate(ValueAnimator valueAnimator) {
                                        List<LatLng> points = greyPolyline.getPoints();
                                        int percentValue = (int) valueAnimator.getAnimatedValue();
                                        int size = points.size();
                                        int newPoints = (int) (size * (percentValue / 100.0f));
                                        List<LatLng> p = points.subList(0, newPoints);
                                        blackPolyline.setPoints(p);

                                    }
                                });

                                polyLineAnimator.start();

                                carMarker = mMap.addMarker(new MarkerOptions()
                                        .position(currentPosition)
                                        .flat(true)
                                        .icon(BitmapDescriptorFactory.fromResource(R.drawable.car)));

                                handler = new Handler();
                                index = -1;
                                next = 1;
                                handler.postDelayed(drawPathRunnable, 2000);
//                                mMap.getUiSettings().setScrollGesturesEnabled(true);
                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }

                        @Override
                        public void onFailure(Call<String> call, Throwable t) {
                            Toast.makeText(DriverHome.this, "" + t.getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    });

        } catch (Exception e) {
            e.printStackTrace();
        }
//        mMap.getUiSettings().setScrollGesturesEnabled(true);
    }

    private List decodePoly(String encoded) {
        List poly = new ArrayList();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;

        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            LatLng p = new LatLng((((double) lat / 1E5)),
                    (((double) lng / 1E5)));
            poly.add(p);
        }
        return poly;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case MY_PEMISSION_REQUEST_CODE:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    buildLocationCallback();
                    buildLocationRequest();
                    if (location_switch.isChecked())
                        displayLocation();
                }
        }

    }

    private void setUpLocation() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            //Request runtime permission
            ActivityCompat.requestPermissions(this, new String[]{

                    Manifest.permission.ACCESS_COARSE_LOCATION,
                    Manifest.permission.ACCESS_FINE_LOCATION
            }, MY_PEMISSION_REQUEST_CODE);

        } else {

            buildLocationRequest();
            buildLocationCallback();
            if (location_switch.isChecked())
                displayLocation();
        }


    }

    private void buildLocationCallback() {
        locationCallback = new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                for (Location location : locationResult.getLocations()) {
                    Common.mLastLocation = location;
                }
                displayLocation();
            }
        };
    }

    private void buildLocationRequest() {

        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(UPDATE_INTERVAL);
        mLocationRequest.setFastestInterval(FATEST_INTERVAL);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest.setSmallestDisplacement(DISPLACEMENT);
    }

    private void displayLocation() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }

        fusedLocationProviderClient.getLastLocation()
                .addOnSuccessListener(new OnSuccessListener<Location>() {

                    @Override
                    public void onSuccess(Location location) {
                        Common.mLastLocation = location;

                        if (Common.mLastLocation != null) {
                            if (location_switch.isChecked()) {
                                final double latitude = Common.mLastLocation.getLatitude();
                                final double longitude = Common.mLastLocation.getLongitude();

                                //Update to Firebase


                                AccountKit.getCurrentAccount(new AccountKitCallback<Account>() {
                                    @Override
                                    public void onSuccess(Account account) {
                                        geoFire.setLocation(account.getId(), new GeoLocation(latitude, longitude), new GeoFire.CompletionListener() {

                                            @Override
                                            public void onComplete(String key, DatabaseError error) {


                                                if (mCurrent != null) {
                                                    mCurrent.remove();
                                                }


                                                mCurrent = mMap.addMarker(new MarkerOptions()
                                                        .position(new LatLng(latitude, longitude))
                                                        .title("Your Location"));

//                                                    Move camera to this position when set to online!
                                                mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude, longitude), 14.5f));

//                                              Draw animation rotate marker
//                                              rotateMarker(mCurrent, 360, mMap);

                                            }
                                        });
                                    }

                                    @Override
                                    public void onError(AccountKitError accountKitError) {

                                    }
                                });
                            }
                        } else {
                            Log.d("ERROR", "Cannot get your location");
                        }
                    }
                });

    }



    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
        mMap.setTrafficEnabled(false);
        mMap.setIndoorEnabled(false);
        mMap.setBuildingsEnabled(false);
        mMap.getUiSettings().setZoomControlsEnabled(false);


        try {
            // Customise the styling of the base map using a JSON object defined
            // in a raw resource file.
            boolean success = googleMap.setMapStyle(
                    MapStyleOptions.loadRawResourceStyle(
                            this, R.raw.style_json));

            if (!success) {
                Log.e("Mitkasin", "Style parsing failed.");
            }
        } catch (Resources.NotFoundException e) {
            Log.e("Mitkasin", "Can't find style. Error: ", e);
        }

        if (ActivityCompat.checkSelfPermission(DriverHome.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(DriverHome.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        buildLocationRequest();
        buildLocationCallback();
        fusedLocationProviderClient.requestLocationUpdates(mLocationRequest, locationCallback, Looper.myLooper());
    }

}

请原谅我的令人讨厌的代码:D抱歉，如果这是一个愚蠢的问题，但我不知道我在这里缺少什么......

Answer 1

仅在 map 初始化后(即 mMap = googleMap)，您才需要调用 displayLocation 和 getDirection 方法。查看相关Null Pointer Exception and getMapAsync Error

例如:

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    mMap.setTrafficEnabled(false);
    mMap.setIndoorEnabled(false);
    mMap.setBuildingsEnabled(false);
    mMap.getUiSettings().setZoomControlsEnabled(false);


    try {
        // Customise the styling of the base map using a JSON object defined
        // in a raw resource file.
        boolean success = googleMap.setMapStyle(
                MapStyleOptions.loadRawResourceStyle(
                        this, R.raw.style_json));

        if (!success) {
            Log.e("Mitkasin", "Style parsing failed.");
        }
    } catch (Resources.NotFoundException e) {
        Log.e("Mitkasin", "Can't find style. Error: ", e);
    }

    displayLocation();
    getDirection();
}

希望这有帮助!