Magirus Magirus - 3 months ago 74
Android Question

NullPointerException: Attempt to read from field 'int android.app.Fragment.mContainerId' on a null object reference

Having some interesting issue with transaction on fragments on Android Lollipop ONLY. Crash happens when i go back and remove previously added fragment.

Here is stacktrace :

FATAL EXCEPTION: main
Process: com.parkme.consumer, PID: 15560
java.lang.NullPointerException: Attempt to read from field 'int android.app.Fragment.mContainerId' on a null object reference
at android.app.BackStackRecord$1.onPreDraw(BackStackRecord.java:1131)
at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:944)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1970)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
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:5254)
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:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)


How i am doing transaction :

getFragmentManager().beginTransaction()
.replace(R.id.list_holder, listFragment)
.commit();


R.id.list_holder

<FrameLayout
android:id="@+id/list_holder"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>


How i remove it :

getFragmentManager().beginTransaction()
.remove(listFragment)
.commit();


And I`m receiving the crash on last code fragment.

UPDATE

After i had removed it has no crashes anymore:

Transition slideTransition = TransitionInflater.from(ParkmeApplication.getContext()).inflateTransition(R.transition.slide_right);
setExitTransition(slideTransition);


slide_right :



<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
<slide
android:duration="@android:integer/config_shortAnimTime"
android:slideEdge="right"/>
</transitionSet>

Answer Source

The deal was in to do not use getFragmentManager() method and use getSupportFragmentManager() instead and extend from v4.app.Fragment class. After i have been moved out from android.app.Fragment it is working now without crashes.

So my recommendation for all if you have such uses of getFragmentManager() and you have anyone support libraries used in your app then just move to support manager. Even it`s working for you. Or you can hit the crash with some strange bug as i did. Thanks to all who got time to give me advices !