GoogleMap NullPointerException with targetSdkVersion 21

我正在研究一个应用程序，其中包括通过选项卡访问的MapFragment。最近，随着Android 5.0 Lollipop的发布，我决定更新材料设计。我进行了必要的更改（在build.gradle中更改SDK，将父主题切换为android:Theme.Material.Light等）。然而，在运行应用程序时，它会给出错误：GoogleMap NullPointerException with targetSdkVersion 21

java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.MapFragment.getMap()' on a null object reference 
     at com.me.myapp.MyActivity$PlaceholderFragment.onCreateView(MyActivity.java:300) 
     at android.app.Fragment.performCreateView(Fragment.java:2053) 
     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:894) 
     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067) 
     at android.app.BackStackRecord.run(BackStackRecord.java:833) 
     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1452) 
     at android.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:483) 
     at android.support.v13.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:145) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:1073) 
     at android.support.v4.view.ViewPager.populate(ViewPager.java:919) 
     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441) 
     at android.view.View.measure(View.java:17430) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
     at android.view.View.measure(View.java:17430) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
     at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:447) 
     at android.view.View.measure(View.java:17430) 
     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) 
     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560) 
     at android.view.View.measure(View.java:17430) 
     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2001) 
     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1166) 
     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1372) 
     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054) 
     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779) 
     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767) 
     at android.view.Choreographer.doCallbacks(Choreographer.java:580) 
     at android.view.Choreographer.doFrame(Choreographer.java:550) 
     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753) 
     at android.os.Handler.handleCallback(Handler.java:739) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:135) 
     at android.app.ActivityThread.main(ActivityThread.java:5221) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

我决定再次通过该补丁，这次每次都会更改一件事。我发现，如果我将targetSdkVersion 20这一行更改为targetSdkVersion 21，那么应用程序会崩溃，与上面相同NullPointerException。但是，将targetSdkVersion保留为20并不会导致错误，并且该应用可以像我期望的那样工作（包括材料设计）。

我明白getMap()可以返回null，我只是，为什么它似乎只发生时targetSdkVersion为21

有任何人碰到这个有点困惑？有什么我做错了吗？

谢谢！

编辑：

我感动，因为从PlaceholderFragment了，但问题仍然存在。

下面是从我onCreateView相关代码：

rootView = inflater.inflate(R.layout.fragment_map, container, false); 

map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map1)).getMap(); // Causes NPE

来源

2014-11-21 kelleyb

你可以发布你的'MyActivity.PlaceholderFragment's的代码'onCreateView（）'方法请求？ NPE发生在该类别的第300行。 – Ridcully 2014-11-21 18:07:57

您正在使用的是哪个版本的Google Play服务？ – 2014-11-21 18:49:03

在我的build.gradle中：'compile'com.google.android.gms：play-services：6.1.71'' – kelleyb 2014-11-21 20:17:24

您类必须扩展FragmentActivity，变标签MAP1到SupportMapFragment

YourActivity yourActivity = (YourActivity)getActivity(); 
    SupportMapFragment mapFragment = (SupportMapFragment)yourActivity.getSupportFragmentManager().findFragmentById(R.id.myFriendsMapFragment); 
    map = mapFragment.getMap();

来源

2015-06-30 12:31:05 AnsonChen

GoogleMap NullPointerException with targetSdkVersion 21

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