在MiniControllerFragment中调用super.onCreateView()时出现NullPointerException

Question

在我的应用程序中,我正在尝试实现一个MiniControlFragment,它会在用户决定关闭时显示ExpandedControlsActivity(Mini控制器的全屏版本).我没有以声明方式将其添加到xml布局中,而是需要以编程方式执行此操作.

所以我创建了自己的类,扩展了MiniControllerFragment:

public class CastControllingFragment extends MiniControllerFragment
{
    @Override
    public View onCreateView(LayoutInflater layoutInflater, ViewGroup viewGroup, Bundle bundle)
    {
        View view = super.onCreateView(layoutInflater, viewGroup, bundle);
        if (view != null) {
            FrameLayout.LayoutParams frameLayoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            view.setLayoutParams(frameLayoutParams);
        }
        return view;
    }

    public static void show(FragmentActivity activity) {
        FragmentManager fragmentManager = activity.getSupportFragmentManager();
        if (fragmentManager.findFragmentById(R.id.castMiniController) == null)
        {
            View rootView = activity.findViewById(R.id.fragment_container);
            if (rootView instanceof ViewGroup)
            {                    
               fragmentManager.beginTransaction().add(R.id.fragment_container, new CastControllingFragment()).commit();
            }
        }
    }

}

我实例并把它添加到片段中的交易Activity的onResume回调:

    @Override
    protected void onResume() {
        CastControllingFragment.show(this);
        super.onResume();
    }

这是我的片段的容器Activity的布局FrameLayout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:app="http://schemas.android.com/apk/res-auto"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
    </FrameLayout>

</RelativeLayout>

但是,当super.onCreateView()我CastControllingFragment在调用时,我得到以下错误:

java.lang.RuntimeException:无法恢复活动java.lang.NullPointerException:尝试在android.app.ActivityThread.handleResumeActivity(ActivityThread.java:android.app.ActivityThread.performResumeActivity(ActivityThread.java:3400)读取空数组. 3440)在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2713)android.app.ActivityThread.-wrap12(ActivityThread.java)android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1460)at android位于java.lang.reflect的android.app.ActivityThread.main(ActivityThread.java:6077)的android.os.Looper.loop(Looper.java:154)中的.os.Handler.dispatchMessage(Handler.java:102).在Com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)的com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:865)中的Method.invoke(Native Method)

引发者:java.lang.NullPointerException:尝试在com.google.android.gms.cast上的com.google.android.gms.cast.framework.media.widget.MiniControllerFragment.zza(未知来源)中读取空数组.在android.support.v4.app.Fragment.performCreateView(Fragment.java)的com.google.sample.cast.refplayer.CastControllingFragment.onCreateView(CastControllingFragment.java:22)上的framework.media.widget.MiniControllerFragment.onCreateView(未知来源) :2087)在android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1113)的android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1295)android.support.v4.app上的android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1113). BackStackRecord.run(BackStackRecord.java:801)android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1682)android.support.v4.app.FragmentController.execPendingActions(FragmentController.java:388)at android android.support.v7.app.AppComp上的.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:499)atActivity.onPostResume(AppCompatActivity.java:175)位于android.app.ActivityThread.handleResumeActivity(ActivityThread)的android.app.ActivityThread.performResumeActivity(ActivityThread.java:3377)上的android.app.Activity.performResume(Activity.java:6792) .java:3440)在android.app.A活动中的android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2713)android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1460)的android.app.ActivityThread.-wrap12(ActivityThread.java) )在android.os.Handler.dispatchMessage(Handler.java:102)的android.app.Looper.loop(Looper.java:154)在android.app.ActivityThread.main(ActivityThread.java:6077)的java.lang上位于com.android.internal.os.ZygoteInit.main的com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:865)中的.reflect.Method.invoke(Native Method)(ZygoteInit.java:755)

Answer 1

最新的Cast SDK发生了变化,导致其与旧版Google Play服务不兼容(崩溃).不幸的是,当使用带有过时GPS(或模拟器)的最新Cast SDK时,甚至投射样本应用程序也会崩溃.这里讨论了这个问题:https://github.com/googlecast/CastVideos-android/issues/12

解决方案是在初始化任何演员组件(包括迷你控制器)之前检查Google Play服务版本(即您不能将迷你控制器片段放入xml布局文件中 - 您必须动态扩充它,或者有两个布局文件 - 一个和,没有你的迷你控制器).

检查GPS版本的代码:

GoogleApiAvailability apiAvailability = GoogleApiAvailability.getInstance();
int resultCode = apiAvailability.isGooglePlayServicesAvailable(context);
isGPSAvailable = (resultCode == ConnectionResult.SUCCESS);

如果结果不是ConnectionResult.SUCCESS,请不要初始化您的MiniControllerFragment.

另外,请记住,这是不是可以实例MiniControllerFragment使用new MiniControllerFragment().你必须从xml充气它,否则你会得到它NullPointerException.

膨胀有两种方法MiniControllerFragment:

1. 创建单独的xml布局文件并在Activity.onCreate以下内容中添加适当的文件:

   setContentView(isGPSAvailable ? R.layout.activity_main_with_controller : R.layout.activity_main_without_controller);
   

2. 只有在有游戏服务时,才能在ViewStub布局中创建指向MiniControllerFragment并对其进行充气.

活动布局:

<ViewStub
android:id="@+id/cast_minicontroller"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout="@layout/cast_mini_controller_fragment"
/>

cast_mini_controller_fragment:

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
          android:id="@+id/castMiniController"
          class="com.google.android.gms.cast.framework.media.widget.MiniControllerFragment"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:visibility="gone"/>

您活动中的代码onCreate():

ViewStub miniControllerStub = (ViewStub) findViewById(R.id.cast_minicontroller);
if (isGPSAvailable) {
    miniControllerStub.inflate();
}

我更喜欢这种ViewStub方法,因为它不会重复您的布局.