android - 当我调用 popBackStack(TAG, POP_BACK_STACK_INCLUSIVE) 和具有共享元素的 fragment 时出现 NullPointerException

Question

我使用 sharedElements 在屏幕之间进行动画转换，当我尝试清除 backStack(2 个 fragment )时，我得到了这个 NullPointer。

这是我的代码:

supportFragmentManager.popBackStackImmediate(TAG,POP_BACK_STACK_INCLUSIVE)

还有这个堆栈跟踪:

? E/MessageQueue-JNI: java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.Collection.contains(java.lang.Object)' on a null object reference
    at android.support.v4.util.MapCollections.retainAllHelper(MapCollections.java:479)
    at android.support.v4.util.ArrayMap.retainAll(ArrayMap.java:161)
    at android.support.v4.app.FragmentTransition.captureOutSharedElements(FragmentTransition.java:799)
    at android.support.v4.app.FragmentTransition.configureSharedElementsOrdered(FragmentTransition.java:698)
    at android.support.v4.app.FragmentTransition.configureTransitionsOrdered(FragmentTransition.java:330)
    at android.support.v4.app.FragmentTransition.startTransitions(FragmentTransition.java:134)
    at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2379)
    at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2337)
    at android.support.v4.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:853)
    at android.support.v4.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:807)

Answer 1

我在我的 Fragment 中设置了 sharedElementsReturnTransition = null 并修复了 Exception。但是，如果您按下后退按钮，您的共享元素将不起作用 - 所以我将 Fragment 替换为分隔 Activity 以解决 backstack 问题。