ViewRootImpl.setPausedForTransition(boolean) 当过早转换到其他 Activity 时，ActivityTransitionCoordinator 中出现 NullPointerException

在我的 Android 应用程序中，我有一个启动屏幕，我可以在其中进行一些设置和加载。我的应用程序使用默认值explode as a windowEnterTransition and a windowExitTransition and a changeImageTransform plus changeBounds过渡集为windowSharedElementEnterTransition and windowSharedElementExitTransition。为了方便，我开始下一个Activity使用静态方法传递当前的Activity as a Context和一个共享元素。该代码在本文的第二部分中提供。

其中一种情况是没有任何内容可加载，因此应用程序几乎立即触发下一个Activity。问题是，在这种情况下，应用程序莫名其妙地崩溃了ActivityTransitionCoordinator以及本文下一部分中给出的堆栈。内部调试表明ViewRootImpl实现的是 null 并且没有 null 检查，因此调用viewRoot.setPausedForTransition(false)抛出一个NullPointerException。您可以在下面的代码中找到标记的这个不幸的地方。

为了关注这个失败的场景，让我们假设一个逻辑决定没有什么可以加载，并且下一个Activity应该立即开始是如此简单，以至于可以简化为仅开始所提到的活动。

如果第二个开始也没有什么区别Activity被调用于onCreate(), onResume(), or onEnterAnimationComplete()方法。我什至尝试在通过调用获取的 Transition 上添加监听器getWindow().getSharedElementEnterTransition() and getWindow().getEnterTransition()被允许开始下一个Activity当转换完成时。给定的Transitions不为空，但应用程序永远不会进入附加侦听器的方法。

我现在使用的解决方法只是安排一个Runnable调用下一个Activity延迟。

我想知道这是否是一个Android (a SupportLibrary更具体地说）问题，或者我错过了一些东西。有人遇到过类似的问题吗？

堆栈跟踪：

08-12 00:35:32.550 26453-26453/com.faver.mkoslacz.faverdemo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.faver.mkoslacz.faverdemo, PID: 26453
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.ViewRootImpl.setPausedForTransition(boolean)' on a null object reference
at android.app.ActivityTransitionCoordinator.startInputWhenTransitionsComplete(ActivityTransitionCoordinator.java:897)
at android.app.ActivityTransitionCoordinator.viewsTransitionComplete(ActivityTransitionCoordinator.java:885)
at android.app.ExitTransitionCoordinator.getExitTransition(ExitTransitionCoordinator.java:318)
at android.app.ExitTransitionCoordinator.beginTransitions(ExitTransitionCoordinator.java:365)
at android.app.ExitTransitionCoordinator.-wrap0(ExitTransitionCoordinator.java)
at android.app.ExitTransitionCoordinator$4.run(ExitTransitionCoordinator.java:216)
at android.app.ActivityTransitionCoordinator.startTransition(ActivityTransitionCoordinator.java:773)
at android.app.ExitTransitionCoordinator.startExit(ExitTransitionCoordinator.java:213)
at android.app.ActivityTransitionState.startExitOutTransition(ActivityTransitionState.java:317)
at android.app.Activity.cancelInputsAndStartExitTransition(Activity.java:3960)
at android.app.Activity.startActivityForResult(Activity.java:3936)
at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:48)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:75)
at android.app.Activity.startActivity(Activity.java:4196)
at com.faver.mkoslacz.faverdemo.activity.AuthorizationActivity.startWithTransiton(AuthorizationActivity.java:45)
at com.faver.mkoslacz.faverdemo.activity.SplashActivity.onEnterAnimationComplete(SplashActivity.java:27)
at android.app.Activity.dispatchEnterAnimationComplete(Activity.java:5852)
at android.app.ActivityThread.handleEnterAnimationComplete(ActivityThread.java:2668)
at android.app.ActivityThread.-wrap10(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1558)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

代码失败ActivityTransitionAnimator:

private void startInputWhenTransitionsComplete() {
    if (mViewsTransitionComplete && mSharedElementTransitionComplete) {
        final View decor = getDecor();
        if (decor != null) {
            final ViewRootImpl viewRoot = decor.getViewRootImpl(); // it's null
            viewRoot.setPausedForTransition(false); // crashes here
        }
        onTransitionsComplete();
    }
}

开始下一个的方法Activity:

public static void startWithTransiton(Activity activity, android.view.View logo) {
    Intent intent = new Intent(activity, AuthorizationActivity.class);
    ActivityOptionsCompat options = ActivityOptionsCompat
            .makeSceneTransitionAnimation(
                    activity,
                    logo,
                    activity.getString(R.string.logoTransfer));
    activity.startActivity(intent, options.toBundle());
}

飞溅Activity内容（简体）：

public class SplashActivity extends AppCompatActivity {

    private static final String TAG = "SplashActivity";

    private View logo;
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);
        logo = findViewById(R.id.logo);

//        AuthorizationActivity.startWithTransiton(this, logo); // will fail

        new Handler().postDelayed(() -> {
            AuthorizationActivity.startWithTransiton(this, logo); // executes flawlessly
        }, 300);

        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
            Transition sharedElementEnterTransition = getWindow().getSharedElementEnterTransition();
            if (sharedElementEnterTransition != null) {
                sharedElementEnterTransition.addListener(new Transition.TransitionListener() {
                    @Override
                    public void onTransitionStart(Transition transition) {
                        Log.d(TAG, "onTransitionStart: never executes");
                    }

                    @Override
                    public void onTransitionEnd(Transition transition) {
                        Log.d(TAG, "onTransitionEnd: never executes");
                    }

                    @Override
                    public void onTransitionCancel(Transition transition) {
                        Log.d(TAG, "onTransitionCancel: never executes");
                    }

                    @Override
                    public void onTransitionPause(Transition transition) {
                        Log.d(TAG, "onTransitionPause: never executes");
                    }

                    @Override
                    public void onTransitionResume(Transition transition) {
                        Log.d(TAG, "onTransitionResume: never executes");
                    }
                });
            }

            Transition enterTransition = getWindow().getEnterTransition();
            if (enterTransition != null) {
                enterTransition.addListener(new Transition.TransitionListener() {
                    @Override
                    public void onTransitionStart(Transition transition) {
                        Log.d(TAG, "onTransitionStart: never executes");
                    }

                    @Override
                    public void onTransitionEnd(Transition transition) {
                        Log.d(TAG, "onTransitionEnd: never executes");
                    }

                    @Override
                    public void onTransitionCancel(Transition transition) {
                        Log.d(TAG, "onTransitionCancel: never executes");
                    }

                    @Override
                    public void onTransitionPause(Transition transition) {
                        Log.d(TAG, "onTransitionPause: never executes");
                    }

                    @Override
                    public void onTransitionResume(Transition transition) {
                        Log.d(TAG, "onTransitionResume: never executes");
                    }
                });
            }
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
//        AuthorizationActivity.startWithTransiton(this, logo); // will fail
    }

    @Override
    public void onEnterAnimationComplete() {
        super.onEnterAnimationComplete();
//        AuthorizationActivity.startWithTransiton(this, logo); // will fail
    }
}

我在使用爆炸活动转换时也面临同样的问题，我发现此代码在 Lollipop 版本中正常运行，但在 Lollipop 之上崩溃了。 即使我也找不到崩溃的原因。但我用另一种方式解决。只是延迟活动转换。我在下面给出了我的代码

public class SplashActivity extends AppCompatActivity {

final Handler handler = new Handler();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_splash);
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            navigate();
        }
    },500);
}

private void navigate() {
    ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(this);
    Intent intent = new Intent(SplashActivity.this, MainActivity.class);
    startActivity(intent, options.toBundle());
}}

添加此功能后，在所有版本中都可以正常工作。