android - 空指针异常 mapview.onResume

Question

我有如下空指针异常

此代码用于工作，但我将 GMS 库升级为 androidx 库

binding.mapView.onResume()

2019-07-11 11:35:05.873 10868-10868/myapp I/DynamiteModule: Considering local module com.google.android.gms.maps_dynamite:0 and remote module com.google.android.gms.maps_dynamite:221
2019-07-11 11:35:05.873 10868-10868/myapp I/DynamiteModule: Selected remote version of com.google.android.gms.maps_dynamite, version >= 221
2019-07-11 11:35:05.935 10868-10868/myapp W/zygote: Skipping duplicate class check due to unrecognized classloader
2019-07-11 11:35:05.998 10868-10868/myapp I/Google Maps Android API: Google Play services client version: 12451000
2019-07-11 11:35:06.016 10868-10868/myapp I/Google Maps Android API: Google Play services package version: 17785018
2019-07-11 11:35:06.216 10868-10868/myapp D/AndroidRuntime: Shutting down VM
2019-07-11 11:35:06.221 10868-10868/myapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: myapp, PID: 10868
    java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.maps.api.android.lib6.impl.bt.o()' on a null object reference
        at com.google.maps.api.android.lib6.impl.de.b(:com.google.android.gms.dynamite_mapsdynamite@17785047@17.7.85 (040308-253824076):15)
        at com.google.android.gms.maps.internal.t.a(:com.google.android.gms.dynamite_mapsdynamite@17785047@17.7.85 (040308-253824076):37)
        at hp.onTransact(:com.google.android.gms.dynamite_mapsdynamite@17785047@17.7.85 (040308-253824076):4)
        at android.os.Binder.transact(Binder.java:604)
        at com.google.android.gms.internal.maps.zza.zzb(Unknown Source:20)
        at com.google.android.gms.maps.internal.zzk.onResume(Unknown Source:20)
        at com.google.android.gms.maps.MapView$zza.onResume(Unknown Source:21)
        at com.google.android.gms.dynamic.zag.zaa(Unknown Source:3)
        at com.google.android.gms.dynamic.zaa.onDelegateCreated(Unknown Source:4)
        at com.google.android.gms.maps.MapView$zzb.createDelegate(Unknown Source:16)
        at com.google.android.gms.dynamic.DeferredLifecycleHelper.zaa(Unknown Source:18)
        at com.google.android.gms.dynamic.DeferredLifecycleHelper.onResume(Unknown Source:56)
        at com.google.android.gms.maps.MapView.onResume(Unknown Source:32)
        at myapp.RoomFragment.onResume(RoomFragment.kt:291)
        at androidx.fragment.app.Fragment.performResume(Fragment.java:2644)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:922)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1881)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1827)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150)
        at android.os.Handler.handleCallback(Handler.java:789)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6694)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:769)

任何机构都可以提供有关正在发生的事情的任何线索吗？

Answer 1

这些是您需要检查的内容:

1. 确保你拥有这两个(我只有 api key 元数据)

   <meta-data
       android:name="com.google.android.geo.API_KEY"
       android:value="@string/google_maps_key" />
   <meta-data
       android:name="com.google.android.gms.version"
       android:value="@integer/google_play_services_version" />
   

2.你在xml中有一个像这样的 fragment ，类属性是正确的，如下所示

 <fragment
   android:id="@+id/google_map_fragment"
   class="com.google.android.gms.maps.SupportMapFragment"
   android:layout_width="match_parent"
   android:layout_height="match_parent"/>

在我的例子中， map fragment 是一个子 fragment ，在另一个 fragment 中。

这个父 fragment 显然不应该是 MapFragment 或 SupportMapFragment。将其从 SupportMapFragment 更改为 Fragment 后， map 显示得非常好。

public class ParentFragment extends Fragment {

现在，如果您正在使用 fragment ，那么试试这个，--> 我不是在 onCreateView 中获取 map ，而是像这样在 onViewCreated 中获取它:

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.rewards_google_map_area);
    if (mapFragment != null) {
        LocationManager locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
        if (locationManager != null && mapFragment.getMap() != null) {
            googleMap=mapFragment.getMap();
            //after this you do whatever you want with the map
        }
    }

 }