我正在研究地理围栏。我已经在我的主要活动中创建了google api客户端，并在另一个片段中使用了GoogleApiClient的对象。现在，我收到此异常，应用程序崩溃了。
这是完整的错误详细信息。
2019-03-07 20:01:56.197 10473-10473/com.example.foodtag E/UncaughtException: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:109)
at com.example.foodtag.MainActivity.getGeofencePendingIntent(MainActivity.java:184)
at com.example.foodtag.CameraFragment.addFence(CameraFragment.java:228)
at com.example.foodtag.CameraFragment.access$000(CameraFragment.java:72)
at com.example.foodtag.CameraFragment$1.onClick(CameraFragment.java:163)
这是我的片段类。
public class CameraFragment extends Fragment implements
AdapterView.OnItemSelectedListener, ResultCallback {
MainActivity help = new MainActivity();
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_camera, container, false);
mStorageRef = FirebaseStorage.getInstance().getReference();
ActivityCompat.requestPermissions((Activity) getContext(),
new String[]{Manifest.permission.CAMERA}, 0);
geofencingClient = LocationServices.getGeofencingClient(getContext());
tag.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
help.populateGeofenceList(); //
Toast.makeText(getContext(), "populated", Toast.LENGTH_SHORT).show();
addFence(); // error in this method
}
});
return view;
}
这是方法定义：
private void addFence() {
if (!MainActivity.mClient.isConnected()) {
Toast.makeText(getContext(), "MClient Not connected", Toast.LENGTH_SHORT).show();
return;
}
try {
if (ActivityCompat.checkSelfPermission((Activity)getContext(), Manifest.permission.ACCESS_FINE_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.
ActivityCompat.requestPermissions((Activity)getContext(), new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION,
android.Manifest.permission.ACCESS_COARSE_LOCATION}, 101);
return;
}
LocationServices.GeofencingApi.addGeofences(MainActivity.mClient,
help.getGeofencingRequest(), //error calling this method which is written in my main activity
help.getGeofencePendingIntent()
).setResultCallback(this);
}catch (SecurityException securityException){
Log.e(TAG,"security exception");
}
}
我的主要活动是这样的
public class MainActivity extends AppCompatActivity implements
AdapterView.OnItemSelectedListener, GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LoaderManager.LoaderCallbacks<Cursor>, LocationListener {
public static final int GEOFENCE_RADIUS = 250;
private static final String LOG_TAG = "MainActivity ";
private static final int MAX_LENGTH = 20;
public double latitude, longitude;
LocationManager locationManager;
public List<Geofence> mGeofenceList = new ArrayList<>();
public static GoogleApiClient mClient;
private Geofencing mGeofencing;
private boolean mIsEnabled;
private CheckBox mRingerPermissionCheckBox;
private static final int PLACE_PICKER_REQUEST = 109;
String Id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (SaveSharedPreference.getPassword(getApplicationContext()).length() == 0) {
Intent i = new Intent(getApplicationContext(), Userlogin.class);
startActivity(i);
}
setupViewPager();
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions((Activity)this,
new String[]{Manifest.permission.CAMERA},0);
return;
}
Location location = locationManager.getLastKnownLocation(locationManager.NETWORK_PROVIDER);
onLocationChanged(location);
// Toast.makeText(this, ""+longitude+latitude, Toast.LENGTH_LONG).show();
buildGoogleApiClient();
LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
if (ContextCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) !=
PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION,
android.Manifest.permission.ACCESS_COARSE_LOCATION}, 101);
//geofencingClient = LocationServices.getGeofencingClient(this);
// Toast.makeText(this, ""+geofencingClient, Toast.LENGTH_LONG).show();
}
}
public synchronized void buildGoogleApiClient() {
mClient = new GoogleApiClient.Builder(getBaseContext())
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mClient.connect();
mGeofencing = new Geofencing(mClient,this);
Toast.makeText(this, ""+mClient, Toast.LENGTH_SHORT).show();
}
private void setupViewPager(){
SectionsPagerAdapter adapter = new SectionsPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new HomeFragment());
adapter.addFragment(new CameraFragment());
adapter.addFragment(new ProfileFragment());
ViewPager viewPager = (ViewPager) findViewById(R.id.container);
viewPager.setAdapter(adapter);
final TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
tabLayout.getTabAt(0).setIcon(R.drawable.ic_food);
tabLayout.getTabAt(1).setIcon(R.drawable.ic_camera);
tabLayout.getTabAt(2).setIcon(R.drawable.ic_account);
/* tabLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
switch()
{
case 1:
Intent i=new Intent( MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(i,0);
}
}
});*/
}
public static String random() {
Random generator = new Random();
StringBuilder randomStringBuilder = new StringBuilder();
int randomLength = generator.nextInt(MAX_LENGTH);
char tempChar;
for (int i = 0; i < randomLength; i++){
tempChar = (char) (generator.nextInt(96) + 32);
randomStringBuilder.append(tempChar);
}
return randomStringBuilder.toString();
}
public void populateGeofenceList(){
mGeofenceList.add(new Geofence.Builder()
.setRequestId(random())
.setCircularRegion(latitude,longitude,GEOFENCE_RADIUS)
.setExpirationDuration(Geofence.NEVER_EXPIRE)
.setTransitionTypes(Geofence.GEOFENCE_TRANSITION_ENTER)
.build());
Id = random();
// Toast.makeText(this, ""+mGeofenceList, Toast.LENGTH_SHORT).show();
}
public GeofencingRequest getGeofencingRequest(){
GeofencingRequest.Builder builder = new GeofencingRequest.Builder();
builder.setInitialTrigger(GeofencingRequest.INITIAL_TRIGGER_ENTER);
builder.addGeofences(mGeofenceList);
return builder.build();
}
public PendingIntent getGeofencePendingIntent(){
Intent intent = new Intent(this, GeofenceTransitionsIntentService.class);
return PendingIntent.getService(this, 0, intent,PendingIntent.FLAG_UPDATE_CURRENT);
}
@NonNull
@Override
public Loader<Cursor> onCreateLoader(int i, @Nullable Bundle bundle) {
return null;
}
@Override
public void onLoadFinished(@NonNull Loader<Cursor> loader, Cursor cursor) {
}
@Override
public void onLoaderReset(@NonNull Loader<Cursor> loader) {
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
@Override
public void onConnected(@Nullable Bundle bundle) {
Log.i(LOG_TAG,"Api connection successful");
// Toast.makeText(this , "onConnected", Toast.LENGTH_SHORT).show();
}
@Override
public void onConnectionSuspended(int i) {
Log.i(LOG_TAG,"API Client connection suspended.");
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
Log.i(LOG_TAG,"API Connection client suspended.");
Toast.makeText(this , "onConectionFailed", Toast.LENGTH_SHORT).show();
}
@Override
public void onResume() {
super.onResume();
buildGoogleApiClient();
}
@Override
public void onStop() {
super.onStop();
try {
if (mClient.isConnecting() || mClient.isConnected()) {
mClient.disconnect();
}
}catch (NullPointerException n){
Toast.makeText(this, ""+ n, Toast.LENGTH_SHORT).show();
}
}
@Override
public void onLocationChanged(Location location) {
latitude=location.getLatitude();
longitude = location.getLongitude();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
}
请帮助我！