Null pointer exception in JobIntentService onDestroy

Question

I am facing issue with JobIntentService in Android 8.1 OS with Signed apk. Where as its working fine with the debug version. Tried with multiple things but couldnt get solution for this. Here is the crash log i got from Crashalytics.

java.lang.RuntimeException: Unable to stop service com.app.xmpp.XmppService@241c51c6: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.JobIntentService$WorkEnqueuer.serviceProcessingFinished()' on a null object reference

        at android.app.ActivityThread.handleStopService(ActivityThread.java:3284)

        at android.app.ActivityThread.access$2300(ActivityThread.java:188)

        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1633)

        at android.os.Handler.dispatchMessage(Handler.java:111)

        at android.os.Looper.loop(Looper.java:210)

        at android.app.ActivityThread.main(ActivityThread.java:5839)

        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:1113)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:879)

     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.JobIntentService$WorkEnqueuer.serviceProcessingFinished()' on a null object reference
        at android.support.v4.app.JobIntentService.onDestroy(JobIntentService.java:479)
        at com.app.xmpp.XmppService.onDestroy(XmppService.java:91)
        at android.app.ActivityThread.handleStopService(ActivityThread.java:3265)
        at android.app.ActivityThread.access$2300(ActivityThread.java:188) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1633) 
        at android.os.Handler.dispatchMessage(Handler.java:111) 
        at android.os.Looper.loop(Looper.java:210) 
        at android.app.ActivityThread.main(ActivityThread.java:5839) 
        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:1113)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:879)

Help me if anyone faced similar issues with JobIntentService.

Please note this problem cannot be resolved with handling Nullpointer exception, because the NPE is occurring at JobIntentService which is part of Android Framework and we cannot modify it and this is particularly happening only in Signed APK.

XMPP Service OnDestroy

@Override
    public void onDestroy() {
        super.onDestroy();

        MyXMPP.instance=null;
        MyXMPP.instanceCreated=false;

        MyXMPP.connection.disconnect();
        xmppConnectionCheckHandler.removeCallbacks(xmppConnectionCheckRunnable);

        System.out.println("--------------Xmpp Service Stopped-----------");
    }

Thanks in advance.

It's a NPE. Looks like `WorkEnqueuer` in `XmppService` on line 91 is null. Show us some code, and mark the specific line where exceptions is thrown — Andrey Busik, Nov 20 '18 at 04:08
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Gokul Nath KP, Nov 20 '18 at 04:16
Could you please show your JobIntentService class so we can look into the code? :) — Brandon, Nov 20 '18 at 04:16
The WorkerEnqueuer is not part of XmppService, Its part of android.support.v4.app.JobIntentService class from Android Framework — Nama, Nov 20 '18 at 04:25
@Nama Yep, instance of `WorkEnqueuer` is null in `XmppService` on line 91 — Andrey Busik, Nov 20 '18 at 04:40
Ok, can you please show us what's happening around XmppService.java:91 ? — Andrey Busik, Nov 20 '18 at 04:50

Andrey Busik · Answer 1 · 2018-11-20T05:10:08.907

0

From JobIntentService class:

@Override
public void onDestroy() {
    super.onDestroy();
    if (mCompatQueue != null) {
        synchronized (mCompatQueue) {
            mDestroyed = true;
            mCompatWorkEnqueuer.serviceProcessingFinished(); //line 479
        }
    }
}

@Override
public void onCreate() {
    super.onCreate();
    if (DEBUG) Log.d(TAG, "CREATING: " + this);
    if (Build.VERSION.SDK_INT >= 26) {
        mJobImpl = new JobServiceEngineImpl(this);
        mCompatWorkEnqueuer = null;
    } else {
        mJobImpl = null;
        ComponentName cn = new ComponentName(this, this.getClass());
        mCompatWorkEnqueuer = getWorkEnqueuer(this, cn, false, 0);
    }
}

Do you perform any manipulation with mCompatWorkEnqueuer or mCompatQueue in your subclass? Say, like setting it to null or super.onCreate() invocation?

Pay attention that execution of line 479 depends on existence of value of mCompatQueue. Also mCompatWorkEnqueuer is set to null in onCreate for API's 26 (8.0) and above

edited Nov 20 '18 at 05:10

answered Nov 20 '18 at 04:57

Andrey Busik

441
3
16

No.. I am not at all using mCompatWorkEnqueuer component in my class.. only the JobIntentService is using it seems – Nama Nov 20 '18 at 07:45
@Nama You can try to move `super.onDestroy()` line at the very bottom of `onDestroy()` method – Andrey Busik Nov 20 '18 at 13:11
@Nama You don't set the value of mCompatQueue too? – Andrey Busik Nov 20 '18 at 13:12
I've tried moving it to bottom. It didnt work. Yes.. no need to set value of mCompatQueue. Just need to call : enqueueWork(context, XmppService.class, JOB_ID, work); – Nama Nov 20 '18 at 14:51

Null pointer exception in JobIntentService onDestroy

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