Fragment中的Android谷歌地图始终显示SupportMapFragment为null

Question

我想构建一个android地图应用程序，Launch应用程序将从SupportMapFragment中获得null(说我的SupportMapFragment为null(，如果你能指出我的错误在哪里，请帮忙，非常感谢。代码、XML和清单如下。

顺便说一下，MapFragment来自BottomNavigationView选项卡

R.id.navigation_map -> {
val mapFragment = MapFragment()
mapFragment.setArguments(intent.extras)
supportFragmentManager.beginTransaction()
.add(R.id.fragment_container, mapFragment).commit()
return@OnNavigationItemSelectedListener true

MapFragment.java

public class MapFragment extends Fragment implements OnMapReadyCallback {
private View rootView;
private AppCompatActivity context;
private SupportMapFragment supportMapFragment;
private GoogleMap map;

public MapFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
rootView = inflater.inflate(R.layout.fragment_map, container, false);
context = (AppCompatActivity) getActivity();
supportMapFragment = (SupportMapFragment) getFragmentManager().findFragmentById(R.id.fragmentmap);
if (supportMapFragment != null) {
supportMapFragment.getMapAsync(this);
getFragmentManager().beginTransaction()
.replace(R.id.fragment_container, supportMapFragment).commit();
} else {
Toast.makeText(context, "Error - Map Fragment was null!!", Toast.LENGTH_SHORT).show();
}
return rootView;
}
@Override
public void onMapReady(GoogleMap googleMap) {
}
}

fragment_map.xml

<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/fragmentmap"
tools:context=".MainActivity"
android:name="com.google.android.gms.maps.SupportMapFragment" />
</android.support.design.widget.CoordinatorLayout>

舱单

<uses-feature
android:glEsVersion="0x00020000"
android:required="true"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<uses-library android:name="org.apache.http.legacy" android:required="false"/>
<activity
android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.geo.API_KEY"
android:value="@string/google_maps_key" />
</application>

Answer 1

如果您在另一个片段中使用片段，那么最好使用getChildFragmentManager，因为它返回一个专用FragmentManager，用于在该Fragment中放置和管理Fragments。

supportMapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.fragmentmap);

参考：getChildFragmentManager