NullPointerException在获取地图片段

-2

我已经阅读了许多关于同一问题的其他答案，但这一个是不同的。NullPointerException在获取地图片段

我的应用程序包含一个活动，显示我在地图中的当前位置。我的主要活动不是显示地图的。

下面是该活性（地图显示活性）的代码：

public class ActivityShowsNearby extends BaseActivity implements GoogleApiClient.ConnectionCallbacks, 
     GoogleApiClient.OnConnectionFailedListener, 
     LocationListener, 
     OnMapReadyCallback { 

    private static final String TAG = "ActivityShowsNearby"; 
    private static GoogleApiClient mGoogleApiClient; 
    private Location mCurrentLocation; 
    private LocationRequest mLocationRequest; 


    private static final int LOCATION_REQUEST_INTERVAL = 1000 * 60; //60 seconds 
    private static final int LOCATION_REQUEST_FASTEST_INTERVAL = 1000 * 60; //60 seconds 


    // Request codes... 


    private GoogleMap mGoogleMap; 
    private static final int DEFAULT_ZOOM = 15; 
    private final LatLng mDefaultLocation = new LatLng(28.636424, 77.374493); 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     Log.v(TAG, "onCreate"); 
     super.onCreate(savedInstanceState); 
     super.setContentView(R.layout.activity_shows_nearby); 

     if (mGoogleApiClient == null) { 
      mGoogleApiClient = new GoogleApiClient.Builder(this) 
        .addConnectionCallbacks(this) 
        .addOnConnectionFailedListener(this) 
        .addApi(LocationServices.API) 
        .build(); 
     } 

    } 


    @Override 
    protected void onStart() { 
     Log.v(TAG, "onStart"); 

     mGoogleApiClient.connect(); 
     super.onStart(); 


    } 

    @Override 
    protected void onResume() { 
     Log.v(TAG, "onResume"); 

     if (mGoogleApiClient.isConnected()) { 
      Log.v(TAG, "Starting location updates..."); 

      startLocationUpdates(); 
     } 
     super.onResume(); 
    } 

    @Override 
    protected void onPause() { 
     Log.v(TAG, "onPause"); 
     if (mGoogleApiClient.isConnected()) { 
      Log.v(TAG, "Removing location updates..."); 
      LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this); 
     } 
     super.onPause(); 
    } 


    @Override 
    protected void onStop() { 
     Log.v(TAG, "onStop"); 

     mGoogleApiClient.disconnect(); 
     super.onStop(); 
    } 


    @Override 
    public void onConnected(Bundle bundle) { 
     startLocationUpdates(); 
     SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
       .findFragmentById(R.id.map); 

     if (mapFragment == null) { 
      Log.v(TAG, "mapFragment is null"); 
     } else { 
      Log.v(TAG, "mapFragment is NOT null"); 

     } 
     mapFragment.getMapAsync(this); 

    } 

    @Override 
    public void onConnectionSuspended(int i) { 
     Log.v(TAG, "mGoogleApiClient connection suspended"); 


    } 

    @Override 
    public void onConnectionFailed(ConnectionResult connectionResult) { 
     Log.v(TAG, "mGoogleApiClient connection failed"); 


    } 

    private void createLocationRequest() { 
     if (mLocationRequest == null) { 
      mLocationRequest = new LocationRequest(); 
      mLocationRequest.setInterval(LOCATION_REQUEST_INTERVAL); 
      mLocationRequest.setFastestInterval(LOCATION_REQUEST_FASTEST_INTERVAL); 
      mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY); 
     } 

    } 

    private void startLocationUpdates() { 
     createLocationRequest(); 
     try { 
      LocationServices.FusedLocationApi.requestLocationUpdates(
        mGoogleApiClient, 
        mLocationRequest, 
        this 
      ); 
     } catch (SecurityException e) { 
      e.printStackTrace(); 
     } 
    } 

    @Override 
    public void onLocationChanged(Location location) { 

     mCurrentLocation = location; 
     updateMap(); 
    } 



    //@SuppressWarnings("MissingPermission") 
    @Override 
    public void onMapReady(GoogleMap googleMap) { 


     Log.v(TAG, "onMapReady"); 
     mGoogleMap = googleMap; 

     updateLocationUI(); 

     if (mCurrentLocation != null) { 
      googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
        new LatLng(mCurrentLocation.getLatitude(), 
          mCurrentLocation.getLongitude()), DEFAULT_ZOOM)); 
     } else { 
      googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(mDefaultLocation, DEFAULT_ZOOM)); 
     } 

    } 

    private void updateMap() { 
     if (mGoogleMap == null) { 
      return; 
     } 
     mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
       new LatLng(mCurrentLocation.getLatitude(), 
         mCurrentLocation.getLongitude()), DEFAULT_ZOOM)); 
    } 


    @SuppressWarnings("MissingPermission") 
    private void updateLocationUI() { 

     if (mGoogleMap == null) { 
      Log.v(TAG, "mGoogleMap is null"); 
      return; 
     } 

     mGoogleMap.setMyLocationEnabled(true); 
     mGoogleMap.getUiSettings().setMyLocationButtonEnabled(true); 


    } 

}

显然，这种活动从中我已创建以显示导航抽屉BaseActivity.java延伸。这里是BaseActivity.java

public class BaseActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{ 

    private static final String TAG = "BaseActivity"; 
    private Toolbar toolbar; 
    private DrawerLayout drawerLayout; 
    private ActionBarDrawerToggle actionBarDrawerToggle; 
    private NavigationView navigationView; 

    //These two values will be used in unison -- see their usage 
    private boolean mDrawerItemClicked; 
    private int mDrawerItemSelectedId; 


    public NavigationView getNavigationView() { 
     return navigationView; 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     Log.d(TAG, "onCreate"); 

     super.onCreate(savedInstanceState); 
    } 

    @Override 
    public void setContentView(int layoutResID) { 
     Log.d(TAG, "setContentView"); 

     super.setContentView(layoutResID); 
     toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 
    } 

    //Other navigation drawer set up codes... 
}

当应用程序第一次运行的代码，我的主要活动出现。然后用户可以打开导航抽屉并选择一个导航抽屉项目来打开我的地图展示活动，例如ActivityShowsNearby，如下图所示。

。

这是问题所在。

从我的主要活动中，我打开导航抽屉并选择show near me打开ActivityShowsNearby。然后我再次按回去主要活动。一切工作正常到这里。但现在，如果我打开导航抽屉，并再次选择show near me重新打开ActivityShowsNearby活动，然后应用程序崩溃。

这里是logcat的三个场合：

击中SHOW NEAR ME第一次。

12-29 16:30:53.696 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onCreate 
12-29 16:30:54.386 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onStart 
12-29 16:30:54.416 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onResume 
12-29 16:30:54.416 8585-8585/sumit.example.com.movie D/InputTransport: Input channel constructed: name='d9453f5 sumit.example.com.movie/com.example.sumit.movie.ActivityShowsNearby (client)', fd=56 
12-29 16:30:54.596 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: Connected to Google play services. 
12-29 16:30:54.636 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: mapFragment is NOT null 
12-29 16:30:54.786 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onMapReady

后，我按从我ActivityShowsNearby回：

12-29 16:31:02.576 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onPause 
12-29 16:31:02.576 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: Removing location updates... 
12-29 16:31:02.986 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onStop 
12-29 16:31:02.996 8585-8585/sumit.example.com.movie D/InputTransport: Input channel destroyed: name='d9453f5 sumit.example.com.movie/com.example.sumit.movie.ActivityShowsNearby (client)', fd=56

最后，当我打开抽屉式导航栏再次点击show near me

12-29 16:31:07.856 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onCreate 
12-29 16:31:07.906 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onStart 
12-29 16:31:07.906 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: onResume 
12-29 16:31:07.906 8585-8585/sumit.example.com.movie D/InputTransport: Input channel constructed: name='d32ef5a sumit.example.com.movie/com.example.sumit.movie.ActivityShowsNearby (client)', fd=82 
12-29 16:31:08.016 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: Connected to Google play services. 
12-29 16:31:08.016 8585-8585/sumit.example.com.movie V/ActivityShowsNearby: mapFragment is null 
12-29 16:31:08.026 8585-8585/sumit.example.com.movie E/AndroidRuntime: FATAL EXCEPTION: main 
                     Process: sumit.example.com.movie, PID: 8585 
                     java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallback)' on a null object reference 
                      at com.example.sumit.movie.ActivityShowsNearby.onConnected(ActivityShowsNearby.java:168) 
                      at com.google.android.gms.common.internal.zzm.zzq(Unknown Source) 
                      at com.google.android.gms.internal.zzaal.zzo(Unknown Source) 
                      at com.google.android.gms.internal.zzaaj.zzvE(Unknown Source) 
                      at com.google.android.gms.internal.zzaaj.onConnected(Unknown Source) 
                      at com.google.android.gms.internal.zzaan.onConnected(Unknown Source) 
                      at com.google.android.gms.internal.zzzy.onConnected(Unknown Source) 
                      at com.google.android.gms.common.internal.zzl$1.onConnected(Unknown Source) 
                      at com.google.android.gms.common.internal.zzf$zzj.zzwZ(Unknown Source) 
                      at com.google.android.gms.common.internal.zzf$zza.zzc(Unknown Source) 
                      at com.google.android.gms.common.internal.zzf$zza.zzu(Unknown Source) 
                      at com.google.android.gms.common.internal.zzf$zze.zzxa(Unknown Source) 
                      at com.google.android.gms.common.internal.zzf$zzd.handleMessage(Unknown Source) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:148) 
                      at android.app.ActivityThread.main(ActivityThread.java:7406) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

有什么问题吗？

请假设我已启用位置权限和设置。

这里是我的activity_show_nearby.xml

<?xml version="1.0" encoding="utf-8"?> 
<android.support.v4.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"> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:fitsSystemWindows="true" 
     android:orientation="vertical" 
     tools:context="com.example.sumit.movie.MovieActivity"> 


     <android.support.v7.widget.Toolbar 
      android:id="@+id/toolbar" 
      android:layout_width="match_parent" 
      android:layout_height="?attr/actionBarSize" 
      android:background="?attr/colorPrimary" 
      android:elevation="4dp" 
      app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" 
      app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/> 

     <!-- Start of replacement of fragment-container--> 


     <LinearLayout 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:orientation="vertical" 
      android:id="@+id/activity_shows_nearby_location_layout"> 

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


     </LinearLayout> 

     <!--End of replacement of fragment container--> 


    </LinearLayout> 


    <android.support.design.widget.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_movie" 
     app:menu="@menu/activity_movie_drawer" /> 

</android.support.v4.widget.DrawerLayout>

来源

2016-12-29 Sumit Jha

请发布'activity_shows_nearby.xml'文件 –

补充，请现在检查。 –

提供[mcve]。这似乎是一个片段事务的简单问题，但这里有许多无用信息的方法 – AxelH

-1

添加class属性，而不是android:name

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

检查更多信息MapFragment

来源

2016-12-29 11:53:48

仍然崩溃.. –

清洁项目，然后再试一次。 –

-1

你的日志显示片段对象为null：

V/ActivityShowsNearby: mapFragment is null

所以你试图调用一个方法（getMapAsync），它会导致错误。

另外，还要确保你将覆盖所有的生命周期方法（发现的onDestroy丢失）

@Override 
public void onDestroy(){ 
    super.onDestroy(); 
}

来源

2016-12-29 11:58:13

重写仅用于调用超类声明的方法是毫无用处的。我相信OP要求了解它为什么只有在重新打开该活动后才有NULL，因为有一个LOG来检查它是否为NULL;） – AxelH

想你的代码除非菜单初始化

app:headerLayout="@layout/nav_header_movie" 
app:menu="@menu/activity_movie_drawer"

片段不为空（日志记录：mapFragment不null）尝试清理并重新编译您的项目

来源

2016-12-29 12:24:46 Oleksandr

NullPointerException在获取地图片段

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