TaskStackBuilder#startActivities() NullPointerException

问题

I have a crash that keeps occurring on 4.4.2 and 4.4.3 devices (although I'm not sure this is an API issue), where in some ParsePushBroadcastReceiver the following code causes a NullPointerException somewhere deep inside the startActivities call.

Intent intent = new Intent(context, SomeActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
TaskStackBuilder.create(context)
            .addParentStack(SomeActivity.class)
            .addNextIntent(intent)
            .startActivities();

I have tried testing to see whether the context was null, however, the Intent instantiation would've caught that. It might also be worth noting that this application is using Parse Push. The crash log for this crash:

java.lang.RuntimeException: Unable to start receiver com.example.app.android.receiver.PushReceiver: java.lang.NullPointerException
       at android.app.ActivityThread.handleReceiver(ActivityThread.java:2567)
       at android.app.ActivityThread.access$1800(ActivityThread.java:161)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1341)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:157)
       at android.app.ActivityThread.main(ActivityThread.java:5356)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
       at dalvik.system.NativeStart.main(NativeStart.java)
Caused by: java.lang.NullPointerException
       at android.os.Parcel.readException(Parcel.java:1471)
       at android.os.Parcel.readException(Parcel.java:1419)
       at android.app.ActivityManagerProxy.startActivities(ActivityManagerNative.java:4494)
       at android.app.Instrumentation.execStartActivitiesAsUser(Instrumentation.java:1496)
       at android.app.Instrumentation.execStartActivities(Instrumentation.java:1458)
       at android.app.ContextImpl.startActivities(ContextImpl.java:1465)
       at android.content.ContextWrapper.startActivities(ContextWrapper.java:350)
       at android.content.ContextWrapper.startActivities(ContextWrapper.java:350)
       at android.support.v4.content.ContextCompatJellybean.startActivities(ContextCompatJellybean.java:26)
       at android.support.v4.content.ContextCompat.startActivities(ContextCompat.java:105)
       at android.support.v4.app.TaskStackBuilder.startActivities(TaskStackBuilder.java:325)
       at android.support.v4.app.TaskStackBuilder.startActivities(TaskStackBuilder.java:301)
       at com.example.app.android.receiver.PushReceiver.routePush(PushReceiver.java:59)
       at com.example.app.android.receiver.PushReceiver.onPushOpen(PushReceiver.java:35)
       at com.parse.ParsePushBroadcastReceiver.onReceive(ParsePushBroadcastReceiver.java:108)
       at android.app.ActivityThread.handleReceiver(ActivityThread.java:2552)
       at android.app.ActivityThread.access$1800(ActivityThread.java:161)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1341)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:157)
       at android.app.ActivityThread.main(ActivityThread.java:5356)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
       at dalvik.system.NativeStart.main(NativeStart.java)

回答1:

I wasn't able to solve this problem as I have a suspicion that this might be a bug specific to 4.4.* devices. As an alternative, I replaced my use of the TaskStackBuilder with creating my activities via PendingIntent.getActivities. In my case, this provided equivalent functionality and it was a straightforward replacement. Perhaps you might find it useful as well.

final Intent parentIntent = new Intent(context, ParentActivity.class);
parentIntent.putExtra(ParentActivity.EXTRA, extraValue);

final Intent childIntent = new Intent(context, ChildActivity.class);
childIntent.putExtra(ChildActivity.EXTRA, extraChildValue);
childIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

final Intent[] intents = new Intent [] {parentIntent, childIntent};
PendingIntent pendingIntent = PendingIntent.getActivities(context, INTENT_REQUEST_CODE, intents, PendingIntent.FLAG_ONE_SHOT);

pendingIntent.send();

来源：https://stackoverflow.com/questions/28754754/taskstackbuilderstartactivities-nullpointerexception