getResources() on a null object referenceを解決したい

前提・実現したいこと

bottom navigation barを押すと、このエラーが出、アプリが落ちる。

アプリでbottom navigation barを押しても落ちないようにしたい。

発生している問題・エラーメッセージ

2019-04-26 12:23:25.187 8956-8956/com.websarva.wings.android.mapsecond E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.websarva.wings.android.mapsecond, PID: 8956
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at com.google.android.gms.maps.model.MapStyleOptions.loadRawResourceStyle(Unknown Source)
        at com.websarva.wings.android.mapsecond.MapsActivity.onMapReady(MapsActivity.java:107)
        at com.google.android.gms.maps.zzak.zza(Unknown Source)
        at com.google.android.gms.maps.internal.zzaq.dispatchTransaction(Unknown Source)
        at com.google.android.gms.internal.maps.zzb.onTransact(Unknown Source)
        at android.os.Binder.transact(Binder.java:499)
        at fv.b(:com.google.android.gms.dynamite_mapsdynamite@16089051@16.0.89 (040408-239467275):14)
        at com.google.android.gms.maps.internal.bd.a(:com.google.android.gms.dynamite_mapsdynamite@16089051@16.0.89 (040408-239467275):4)
        at com.google.maps.api.android.lib6.impl.bk.run(:com.google.android.gms.dynamite_mapsdynamite@16089051@16.0.89 (040408-239467275):4)
        at android.os.Handler.handleCallback(Handler.java:761)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:156)
        at android.app.ActivityThread.main(ActivityThread.java:6617)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)

該当のソースコード

java
1//mapsActivity.java
2@Override
3    public void onCreate(Bundle savedInstanceState) {
4        super.onCreate(savedInstanceState);
5
6
7        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
8        SupportMapFragment mapFragment = (SupportMapFragment) getFragmentManager().findFragmentById(R.id.map);
9
10        if (mapFragment != null) {
11            mapFragment.getMapAsync(this);
12        }
13
14        //This class automatically initializes the maps system and the view.
15    }
16
17
18
19
20
21    @Override
22    public View onCreateView(LayoutInflater inflater, ViewGroup container,
23                             Bundle savedInstanceState){
24
25
26        View view;
27        view = inflater.inflate(R.layout.activity_maps, container,
28                false);
29
30
31
32
33        return view;
34    }
35
36    @Override
37    public void onActivityCreated(Bundle savedInstanceState){
38        super.onActivityCreated(savedInstanceState);
39
40        SupportMapFragment mapFragment = (SupportMapFragment) this.getChildFragmentManager()
41               .findFragmentById(R.id.map);
42
43        mapFragment.getMapAsync(this);
44    }
45
46
47    /**
48     * Manipulates the map once available.
49     * This callback is triggered when the map is ready to be used.
50     * This is where we can add markers or lines, add listeners or move the camera. In this case,
51     * we just add a marker near Sydney, Australia.
52     * If Google Play services is not installed on the device, the user will be prompted to install
53     * it inside the SupportMapFragment. This method will only be triggered once the user has
54     * installed Google Play services and returned to the app.
55     */
56    @Override
57    public void onMapReady(GoogleMap googleMap) {
58        mMap = googleMap;
59        try {
60            // Customise the styling of the base map using a JSON object defined
61            // in a raw resource file.
62            boolean success = googleMap.setMapStyle(
63                    MapStyleOptions.loadRawResourceStyle(
64                            _parentActivity, R.raw.style_json));//ここがMapsActivity.java:107です
65            if (!success) {
66                Log.e(TAG, "Style parsing failed.");
67            }
68        } catch (Resources.NotFoundException e) {
69            Log.e(TAG, "Can't find style. Error: ", e);
70        }
71
72
73        Log.wtf(TAG, "onMapReady: is started");
74
75        checkPermission_or_request();
76
77
78
79
80
81
82    }

java
1public class MainActivity extends AppCompatActivity {
2
3    final Fragment fragment1 = new MapsActivity();
4    final Fragment fragment2 = null;
5    final Fragment fragment3 = null;
6    final FragmentManager fm = getSupportFragmentManager();
7    Fragment active = fragment1;
8
9    @Override
10    protected void onCreate(final Bundle savedInstanceState) {
11
12        super.onCreate(savedInstanceState);
13        setContentView(R.layout.activity_main);
14        BottomNavigationView bottomNavigationView = findViewById(R.id.bottom_navigation);
15
16
17        BottomNavigationView.OnNavigationItemSelectedListener nav_handler = new BottomNavigationView.OnNavigationItemSelectedListener() {
18
19            int saved_state = 0;
20            @Override
21            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
22
23                switch (item.getItemId()) {
24                    case R.id.action_recents:
25                        Toast.makeText(MainActivity.this, "Recent", Toast.LENGTH_SHORT).show();
26                        if (saved_state == 0) {
27                            active = fragment1;
28                        }
29                        break;
30
31                    case R.id.action_favorites:
32                        if (saved_state == 0) {
33                            active = fragment2;
34                        }
35                        Toast.makeText(MainActivity.this, "Favorites", Toast.LENGTH_SHORT).show();
36                        break;
37
38                    case R.id.action_nearby:
39                        if (saved_state == 0) {
40                            active = fragment3;
41                        }
42                        Toast.makeText(MainActivity.this, "Nearby", Toast.LENGTH_SHORT).show();
43                        break;
44                }
45
46
47                if (savedInstanceState == null) {
48
49                    saved_state = 1;
50
51
52                    FragmentManager manager = getSupportFragmentManager();
53                    FragmentTransaction transaction = manager.beginTransaction();
54                    transaction.replace(R.id.frame_layout, active);
55
56                    transaction.commit();
57
58
59
60                }
61
62                return true;
63
64            }
65        };
66
67        bottomNavigationView.setOnNavigationItemSelectedListener(nav_handler);
68    }
69
70
71}
72

xml
1<?xml version="1.0" encoding="utf-8"?>
2<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
3    xmlns:tools="http://schemas.android.com/tools"
4    android:layout_width="match_parent"
5    android:layout_height="match_parent"
6    tools:context=".MapsActivity">
7
8    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
9        xmlns:tools="http://schemas.android.com/tools"
10        android:id="@+id/map"
11        android:name="com.google.android.gms.maps.SupportMapFragment"
12        android:layout_width="match_parent"
13        android:layout_height="match_parent"
14        tools:context=".MapsActivity" />
15
16</FrameLayout>
17

xml
1<?xml version="1.0" encoding="utf-8"?>
2<RelativeLayout
3    xmlns:android="http://schemas.android.com/apk/res/android"
4    xmlns:app="http://schemas.android.com/apk/res-auto"
5    android:layout_width="match_parent"
6    android:layout_height="match_parent">
7
8    <FrameLayout
9        android:id="@+id/frame_layout"
10        android:layout_width="match_parent"
11        android:layout_height="match_parent"
12        android:layout_above="@+id/bottom_navigation"
13        android:animateLayoutChanges="true">
14
15    </FrameLayout>
16
17
18
19    <android.support.design.widget.BottomNavigationView
20        android:id="@+id/bottom_navigation"
21        android:layout_width="match_parent"
22        android:layout_height="wrap_content"
23        android:layout_alignParentBottom="true"
24        app:menu="@menu/bottom_nav_menu"
25        app:itemBackground="@color/colorPrimary"
26        app:itemIconTint="@android:color/white"
27        app:itemTextColor="@android:color/white" />
28</RelativeLayout>
29

試したこと

getMapAsyncをonActivityCreatedに移したり、savedInstanceState==nullのときだけFragmentをセットするようにしたりしましたが、うまくいきませんでした。

補足情報（FW/ツールのバージョンなど）

swordone

2019/04/26 04:57

_parentActivityとは何ですか？

akaikesan

2019/04/26 05:30 編集

先ほど気づいてgetActivity()を代入したのですが同じエラーが出ました _parentActivity= new Mainactivity() とするとアプリが起動してすぐに落ちますエラーが起こっていないということはMainActivityのことなのでしょうか？ここが原因のようですかね？ fragmentActivity からfragment にしたのでここがcontext型の引数になっているようです。何を入れるべきかお教えいただけませんか？