mapFragment.getMapAsync（this）在地图中返回null
我正在尝试使用Google地图和导航抽屉设计应用程序，但我不断尝试调用虚拟方法'void com.google.android.gms.maps.SupportMapFragment.getMapAsync（com.google.android.gms.maps.OnMapReadyCallbak ）'出现空对象引用错误，我不知道自己在做什么错
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>
最佳答案
这对我来说很好：
<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" />
您已使用ID映射定义了FrameLayout。该如何自动映射到片段？
另外，在调用
getMapAsync之前检查映射片段的可为空性是一个好习惯：SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
if (mapFragment != null) {
mapFragment.getMapAsync(this);
}
希望这可以帮助！