mapFragment.getMapAsync(this( 在 map 中返回 null
我正在尝试设计一个带有谷歌地图和导航抽屉的应用程序，我一直尝试调用虚拟方法'void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallbak('在空对象引用错误上，我不知道我做错了什么
public class MainActivity extends AppCompatActivity implements OnMapReadyCallback {
private AppBarConfiguration mAppBarConfiguration;
private GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
/*FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});*/
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow,
R.id.nav_tools, R.id.nav_share, R.id.nav_send)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
//Implementing Google Map getChildFragmentManager
SupportMapFragment mapFragment = (SupportMapFragment)this.getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
/* SupportMapFragment mapFragment = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map);
if (mapFragment != null) {
mapFragment.getMapAsync(this);
}*/
//Initializing place
if (!Places.isInitialized()) {
Places.initialize(getApplicationContext(), "MY_API_KEY");
}
googlePlaceLocation();
googlePlaceDestination();
}
private void googlePlaceLocation(){
/*//Places Api
places = (PlaceAutocompleteFragment)getFragmentManager().findFragmentById(R.id.place_location);
places.setOnPlaceSelectedListener(new PlaceSelectionListener() {
@Override
public void onPlaceSelected(Place place) {
mMap.clear();
mMap.addMarker(new MarkerOptions().position(place.getLatLng()).title(place.getName().toString()));
mMap.moveCamera(CameraUpdateFactory.newLatLng(place.getLatLng()));
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(place.getLatLng(), 12.0f));
destination = place.getAddress().toString();
destination = destination.replace("","+");
}
@Override
public void onError(Status status) {
Toast.makeText(MapsActivity.this, ""+status.toString(), Toast.LENGTH_SHORT).show();
}
});*/
}
private void googlePlaceDestination() {
// Initialize the AutocompleteSupportFragment.
AutocompleteSupportFragment autocompleteFragment = (AutocompleteSupportFragment)
getSupportFragmentManager().findFragmentById(R.id.place_destination);
autocompleteFragment.setPlaceFields(Arrays.asList(Place.Field.ID, Place.Field.NAME));
autocompleteFragment.setOnPlaceSelectedListener(new PlaceSelectionListener() {
@Override
public void onPlaceSelected(Place place) {
// TODO: Get info about the selected place.
Log.i("TAG", "Place: " + place.getName() + ", " + place.getId());
}
@Override
public void onError(Status status) {
// TODO: Handle the error.
Log.i("TAG", "An error occurred: " + status);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.addMarker(new MarkerOptions()
.position(new LatLng(37.7750, 122.4183))
.title("San Francisco"));
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(37.7750, 122.4183), 15));
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/app_bar_main">
<fragment
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/mobile_navigation" />
<!-- <fragment
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Welcome" />-->
<FrameLayout
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/nav_host_fragment" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<com.google.android.material.navigation.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer" />
</androidx.drawerlayout.widget.DrawerLayout>
这对我来说很好用：
<fragment
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/nav_host_fragment" />
您已经定义了一个带有 id 映射的框架布局。这如何自动映射到片段？
此外，在调用getMapAsync之前检查映射片段的可空性是一种很好的做法：
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
if (mapFragment != null) {
mapFragment.getMapAsync(this);
}
希望这有帮助！
我能够通过将代码移动到 Home 片段来解决问题
import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.Nullable;
import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;
import com.ckhardbyte.barzokarider.R;
import com.firebase.geofire.GeoFire;
import com.firebase.geofire.GeoLocation;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
public class HomeFragment extends Fragment
implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,
LocationListener {
//private HomeViewModel homeViewModel;
private static final String TAG = "MainActivity";
//Declaring Variables
private GoogleMap mMap;
//Play Services
private static final int MY_PERMISSION_REQUEST_CODE = 7000;
private static final int PLAY_SERVICE_RES_REQUEST = 7001;
private LocationRequest mLocationRequest;
private GoogleApiClient mGoogleApiClient;
private Location mLastLocation;
private static int UPDATE_INTERVAL = 5000;
private static int FATEST_INTERVAL = 3000;
private static int DISPLACEMENT = 10;
DatabaseReference drivers;
GeoFire geoFire;
Marker mCurrent;
//MaterialAnimatedSwitch location_switch;
SupportMapFragment mapFragment;
private GoogleMap googleMap;
private GoogleApiClient GoogleApiClient;
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
//Geo Fire
drivers = FirebaseDatabase.getInstance().getReference("Drivers");
geoFire = new GeoFire(drivers);
// Inflate the layout for this fragment
View root = inflater.inflate(R.layout.fragment_home, container, false);
SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
if (mapFragment == null) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
mapFragment = SupportMapFragment.newInstance();
fragmentTransaction.replace(R.id.map, mapFragment).commit();
}
mapFragment.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap mMap) {
googleMap = mMap;
//Getting the user's location
setUpLocation();
}
});
return root;
}
而 XML 是
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:layout_marginLeft="9dp"
android:layout_marginRight="9dp"
android:layout_marginTop="20dp"
app:cardElevation="11dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<LinearLayout
android:weightSum="6"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.AppCompatImageView
android:layout_weight="1"
android:src="@drawable/ic_pin_drop_black_24dp"
android:layout_width="0dp"
android:layout_height="wrap_content" />
<fragment
android:id="@+id/place_location"
android:layout_weight="5"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:name="com.google.android.libraries.places.widget.AutocompleteSupportFragment"/>
</LinearLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginRight="16dp"
android:layout_marginLeft="16dp"
android:background="@color/quantum_black_divider">
</View>
<LinearLayout
android:weightSum="6"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.AppCompatImageView
android:layout_weight="1"
android:src="@drawable/ic_map_black_24dp"
android:layout_width="0dp"
android:layout_height="wrap_content" />
<fragment
android:id="@+id/place_destination"
android:layout_weight="5"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:name="com.google.android.libraries.places.widget.AutocompleteSupportFragment"/>
</LinearLayout>
</LinearLayout>
</androidx.cardview.widget.CardView>
<FrameLayout
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
方法设置位置包含此代码
// For showing a move to my location button
googleMap.setMyLocationEnabled(true);
// For dropping a marker at a point on the Map
LatLng mCurrentLoc = new LatLng( -33.86, 151.20);
googleMap.addMarker(new MarkerOptions().position(mCurrentLoc).title("YOU"));
// For zooming automatically to the location of the marker
CameraPosition cameraPosition = new CameraPosition.Builder().target(mCurrentLoc).zoom(15).build();
googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));