小编Ser*_*mov的帖子

我正在使用MotionLayout时遇到一个奇怪的问题

当我从更改了使用的库版本时 com.android.support.constraint:constraint-layout:2.0.0-alpha2为com.android.support.constraint:constraint-layout:2.0.0-alpha3

我的应用崩溃了：

E/AndroidRuntime: FATAL EXCEPTION: main
Process: ru.sergik.collapsibleexoplayer, PID: 1376
java.lang.NullPointerException: Attempt to invoke virtual method 'int androidx.constraintlayout.motion.widget.MotionScene.getDuration()' on a null object reference
    at androidx.constraintlayout.motion.widget.MotionLayout.dispatchDraw(MotionLayout.java:1634)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at androidx.constraintlayout.widget.ConstraintLayout.dispatchDraw(ConstraintLayout.java:2072)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at android.view.View.updateDisplayListIfDirty(View.java:19306)
    at android.view.View.draw(View.java:20093)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
    at …