Odd logcat error when switching to new fragment

Question

I haven't encountered a stack trace such as this. It's particularly weird because I can only get the error to be thrown when debugging. (Running the app without debugging does not yield this error). This happens upon selecting a particular page from my navigation drawer. I have just recently switched from activities to fragments and I may not have handled my fragment transactions correctly. I would appreciate any input! Thanks a lot guys, happy holidays!

Here's the stack trace:

Process: com.kohlerbear.whowascnscalc, PID: 2415
java.lang.NullPointerException: Attempt to read from field 'boolean android.support.v4.app.BackStackRecord.mAddToBackStack' on a null object reference
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:685)
        at android.support.v4.app.FragmentManagerImpl.execPeerrorndingActions(FragmentManager.java:1479)
        at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:447)
        at android.os.Handler.handleCallback(Handler.java:740)
        at android.os.Handler.dispatchMessage(Handler.java:104)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5223)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

And here is how I am handling my fragment change (Not sure if this is the problem, just judging by the fact that the trace mentions the backstack). The app crashes (again, only when debugging) regardless of whether or not I call ft.addToBackStack(null) .

Fragment frag = new ThirdScreenFragment(); 
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.content_frame, frag);
ft.addToBackStack(null);
ft.commit();`

Any ideas and input are appreciated :)

May be similar in nature to http://stackoverflow.com/questions/13393693/android-fragmentmanager-backstackrecord-run-throwing-nullpointerexception — Kai, Dec 26 '14 at 01:08

score 26 · Answer 1 · answered Apr 24 '15 at 14:47

I recently ran into the same error message in Android studio. I could run my application but once I tried to start debugging, I would receive "Attempt to read from field 'boolean android.support.v4.app.BackStackRecord.mAddToBackStack' on a null object reference". The solution was to select in Android Studio, Run (toolbar) -> View Break Points -> disable each break point one by one until debugging started to work again. Doing this doesn't remove the break point entirely it simply disables them, so there's no need to worry that you'd need to remove all your break points to find the one causing the issue. It seems that one of the break points I had setup in a IntentService class was causing the issue. I'm not sure why it was causing an issue, but it seemed to fix this error for me.

Worked for me too. But seems to be bug in Android Studio. My version is 1.2.2 — Sukitha Udugamasooriya, Sep 01 '15 at 02:05

score 18 · Accepted Answer · answered Mar 29 '15 at 06:57

18

I found a workaround for this issue. Put a breakpoint in the android.support.v4.app.BackStackRecord.run() method and set break condition to false.

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answered Mar 29 '15 at 06:57

h6ah4i

385
4
8

How did you think to do that?? Thank you! – nasch Aug 05 '16 at 21:06

Odd logcat error when switching to new fragment

2 Answers2