几周以来，当程序试图在地图上放置标记时，我得到空指针异常。我不知道为什么，我尝试了几种解决方案，但它们没有用。我在几台设备上收到此错误。例如，100个设备没有错误，但在5个或更多设备中出现此错误 我也无法使用.getMap（）函数。只有getMapAsync可用。
以下是我从Firebase获得的错误：
Fatal Exception: java.lang.NullPointerException
Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.animateCamera(com.google.android.gms.maps.CameraUpdate)' on a null object reference
以下是Google地图片段：
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/map1"
class="com.google.android.gms.maps.SupportMapFragment"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.ahmetbesli.eczanem.MapsActivityPicker"
/>
以下是我的程序代码：
public class MapsActivityPicker extends FragmentActivity implements OnMapReadyCallback, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, View.OnClickListener {
SharedPreferences sharedPreferences;
GoogleMap mGoogleMap;
SupportMapFragment mapFrag;
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
FusedLocationProviderClient mFusedLocationClient;
LocationManager mLocationManager;
ArrayList<MarkerData> markers = new ArrayList<>();
int counter = 1;
int resumeCounter = 2;
boolean add = true;
LatLng midLatLng;
LatLng latLngMaps;
ImageView direction;
ImageView bullet;
ImageView share;
ImageView nearMe;
ImageView call;
CountDownTimer timer;
String pharmacyName;
String pharmacyAddress;
String markerPhone = null;
Double markerLatitude;
Double markerLongitude;
private InterstitialAd mInterstitialAd;
String shortURL;
LocationCallback mLocationCallback;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps_picker);
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
mapFrag = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map1);
buildGoogleApiClient();
mapFrag.getMapAsync(this);
mLocationManager = (LocationManager) MapsActivityPicker.this
.getSystemService(Context.LOCATION_SERVICE);
direction = findViewById(R.id.directionPicker);
bullet = findViewById(R.id.bulletPicker);
share = findViewById(R.id.sharePicker);
nearMe = findViewById(R.id.accessPicker);
call = findViewById(R.id.callPicker);
direction.setOnClickListener(this);
bullet.setOnClickListener(this);
share.setOnClickListener(this);
nearMe.setOnClickListener(this);
call.setOnClickListener(this);
sharedPreferences = this.getApplication().getSharedPreferences(Config.app_name,MODE_PRIVATE);
mInterstitialAd = new InterstitialAd(this);
mInterstitialAd.setAdUnitId("xxxxxxxxxx");
mInterstitialAd.loadAd(new AdRequest.Builder().build());
timer = new CountDownTimer(5000, 1000)
{
public void onTick(long millisUntilFinished) {
}
public void onFinish() {
if (add) {
if (mInterstitialAd != null) {
if (mInterstitialAd.isLoaded()) {
mInterstitialAd.show();
}
}
}
}
};
timer.start();
}
@Override
public void onPause() {
super.onPause();
if (mFusedLocationClient != null) {
mFusedLocationClient.removeLocationUpdates(mLocationCallback);
}
}
@Override
public void onMapReady(final GoogleMap googleMap) {
mGoogleMap = googleMap;
mGoogleMap.getUiSettings().setMapToolbarEnabled(false);
mGoogleMap.setInfoWindowAdapter(new CustomInfoWindowAdapter(MapsActivityPicker.this));
mGoogleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
public void onMapClick(LatLng latLng) {
bullet.setVisibility(View.VISIBLE);
share.setVisibility(View.GONE);
direction.setVisibility(View.GONE);
nearMe.setVisibility(View.VISIBLE);
call.setVisibility(View.GONE);
}
});
mGoogleMap.setOnInfoWindowClickListener(new GoogleMap.OnInfoWindowClickListener() {
@Override
public void onInfoWindowClick(Marker marker) {
Intent intent = new Intent(MapsActivityPicker.this, HomePageShared.class);
intent.putExtra("name",marker.getTitle());
intent.putExtra("address",marker.getSnippet());
intent.putExtra("phone",markerPhone);
intent.putExtra("latitude",marker.getPosition().latitude);
intent.putExtra("longitude",marker.getPosition().longitude);
intent.putExtra("userLatitude", midLatLng.latitude);
intent.putExtra("userLongitude",midLatLng.longitude);
startActivity(intent);
}
});
mGoogleMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
Marker currentShown;
@Override
public boolean onMarkerClick(Marker marker) {
if (marker.equals(currentShown)) {
marker.hideInfoWindow();
currentShown = null;
} else {
marker.showInfoWindow();
currentShown = marker;
}
pharmacyName = marker.getTitle();
pharmacyAddress = marker.getSnippet();
markerLatitude = marker.getPosition().latitude;
markerLongitude = marker.getPosition().longitude;
for(int i = 0; i < markers.size(); i++){
if(markers.get(i).getName().equals(pharmacyName)){
markerPhone = markers.get(i).getPhone();
}
}
shortURL = "http://maps.google.com/maps?daddr=" + markerLatitude + "," + markerLongitude;
latLngMaps = marker.getPosition();
share.setVisibility(View.VISIBLE);
direction.setVisibility(View.VISIBLE);
bullet.setVisibility(View.GONE);
nearMe.setVisibility(View.GONE);
call.setVisibility(View.VISIBLE);
return true;
}
});
googleMap.setOnCameraIdleListener(new GoogleMap.OnCameraIdleListener() {
@Override
public void onCameraIdle() {
//get latlng at the center by calling
midLatLng = googleMap.getCameraPosition().target;
//request();
requestRetrofit();
googleMap.clear();
}
});
if(sharedPreferences.getBoolean(Config.theme,false)){
mGoogleMap.setMapStyle(MapStyleOptions.loadRawResourceStyle(this, R.raw.night_mode));
}
}
protected void getGPS() {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
this);
alertDialogBuilder
.setMessage("Konum Servisiniz kapalı. Eczaneleri görebilmek için lütfen açınız.")
.setCancelable(false)
.setPositiveButton("Konum Servisini Aç",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int id) {
Intent callGPSSettingIntent = new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
MapsActivityPicker.this.startActivity(callGPSSettingIntent);
}
});
alertDialogBuilder.setNegativeButton("Kapalı Kalsın",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert = alertDialogBuilder.create();
alert.show();
}
public void requestRetrofit(){
ApiInterface apiInterface = ApiClient.getRetrofit().create(ApiInterface.class);
Call<ArrayList<Eczane>> call = apiInterface.getPharmacies(new com.ahmetbesli.eczanem.Request(String.valueOf(midLatLng.latitude),String.valueOf(midLatLng.longitude)));
call.enqueue(new Callback<ArrayList<Eczane>>() {
@Override
public void onResponse(Call<ArrayList<Eczane>> call, retrofit2.Response<ArrayList<Eczane>> response) {
markers.clear();
if (response.body().get(0) != null) {
for (int i = 0; i < 5; i++) {
if (!response.body().get(i).getLatitude().equals("undefined") && !response.body().get(i).getLongitude().equals("undefined") && !response.body().get(i).getLatitude().equals("") && !response.body().get(i).getLongitude().equals("")) {
createMarker(Double.valueOf(response.body().get(i).getLatitude()),
Double.valueOf(response.body().get(i).getLongitude()), response.body().get(i).getName(),
response.body().get(i).getAdress(), response.body().get(i).getPhone(), R.mipmap.marker);
}
}
}
}
@Override
public void onFailure(Call<ArrayList<Eczane>> call, Throwable t) {
}
});
}
protected void starter() {
//Initialize Google Play Services
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
//Location Permission already granted
buildGoogleApiClient();
} else {
//Request Location Permission
checkLocationPermission();
}
} else {
buildGoogleApiClient();
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
@Override
public void onConnected(Bundle bundle) {
mLocationRequest = LocationRequest.create();
mLocationRequest.setInterval(120000); // two minute interval
mLocationRequest.setFastestInterval(120000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
private void checkLocationPermission() {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
new AlertDialog.Builder(this)
.setTitle("Konum Servisi için izin gerekli.")
.setMessage("Bu uygulama konum servisi iznine ihtiyaç duymaktadır. Lütfen kabul ediniz.")
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(MapsActivityPicker.this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
})
.create()
.show();
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted, yay! Do the
// location-related task you need to do.
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient == null) {
buildGoogleApiClient();
}
}
} else {
// permission denied, boo! Disable the
// functionality that depends on this permission.
Toast.makeText(this, "İzin Reddedildi", Toast.LENGTH_LONG).show();
}
}
// other 'case' lines to check for other
// permissions this app might request
}
}
@Override
public void onResume() {
super.onResume();
if (resumeCounter <= 2) {
starter();
resumeCounter++;
}
if (counter == 0) {
if (mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
starter();
counter++;
} else {
getGPS();
counter++;
}
}
}
protected void createMarker(double latitude, double longitude, String title, String snippet, String phone, int iconResID) {
MarkerData marker = new MarkerData(title, snippet, phone, latitude, longitude);
markers.add(marker);
mGoogleMap.addMarker(new MarkerOptions()
.position(new LatLng(latitude, longitude))
.anchor(0.5f, 0.5f)
.title(title)
.snippet(snippet)
.icon(BitmapDescriptorFactory.fromResource(iconResID)));
}
@Override
protected void onStart(){
super.onStart();
mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
for (Location location : locationResult.getLocations()) {
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
mGoogleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 10.7f));
}
}
};
}
}
答案 0 :(得分：1)
在onStart方法中，您可能在未分配mGoogleMap.animateCamera()时调用onMapReady。它是在if(mGoogleMap != null){
mGoogleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 10.7f));
}
中分配的
你需要检查它是否为空。
onMapReady()我怀疑你有竞争条件：在某些设备上onLocationResult()方法在onLocationResult()之前被调用...所以一切正常。但在onMapReady()方法之前调用其他设备null，因此mGoogleMap为//create a class variable mLatLng
private LatLng mLatLng;
！因此，您必须检查是否＆＃34; mGoogleMap＆＃34;已被分配。
请改为：
onLocationResult()现在将public void onLocationResult(LocationResult locationResult) {
for (Location location : locationResult.getLocations()) {
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
mLatLng = new LatLng(location.getLatitude(), location.getLongitude());
moveMapTo();
}
方法中的代码更改为：
private void moveMapTo(){
if(mLatLng == null) return;
if(mGoogleMap != null){
mGoogleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10.7f));
}
}
添加方法：
onMapReady()在moveMapTo();
方法中，您只需要添加：
onLocationResult()这种方式在onMapReady()之前调用onMapReady()变量＆＃34; mLatLng＆＃34}已定义且有效，但＆＃34; mGoogleMap＆＃34;为null - 这会导致错误。一旦＆＃34; mGoogleMap＆＃34;已在moveMapTo() onMapReady()中正确定义并再次调用，并将您的动画设置为正确的位置。但是，如果在onLocationResult()之前调用了onLocationResult()，那么＆＃34; mGoogleMap＆＃34;已经分配，并且在Clip中一切都按预期工作。