We are periodically running into this issue with our Dagger 2 components. It seems to be occurring after a period of idle. It is not always reproducible. Here is the stacktrace:
--------- beginning of crash
05-19 14:06:22.145 31322-31322/org.mythtv.android E/AndroidRuntime: FATAL EXCEPTION: main
Process: org.mythtv.android, PID: 31322
java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object org.mythtv.android.presentation.internal.di.HasComponent.getComponent()' on a null object reference
at org.mythtv.android.app.view.fragment.AbstractBaseFragment.getComponent(AbstractBaseFragment.java:67)
at org.mythtv.android.app.view.fragment.EncoderListFragment.initialize(EncoderListFragment.java:139)
at org.mythtv.android.app.view.fragment.EncoderListFragment.reload(EncoderListFragment.java:194)
at org.mythtv.android.app.view.activity.MainActivity$1.onClick(MainActivity.java:115)
at android.view.View.performClick(View.java:5204)
at android.view.View$PerformClick.run(View.java:21153)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Here is the code that is blowing up:
/**
* Gets a component for dependency injection by its type.
*/
@SuppressWarnings( "unchecked" )
protected <C> C getComponent( Class<C> componentType ) {
return componentType.cast( ( (HasComponent<C>) getActivity() ).getComponent() );
}
This is called when the fragments initialize. The key item here is that these fragments are members of a ViewPager. The fragments are created and initialized as a part of the constructor of the FragmentStatePagerAdapter:
public MainFragmentPagerAdapter( FragmentManager fm ) {
super( fm );
tabs = getResources().getStringArray( R.array.main_tabs );
fragments.add( Fragment.instantiate( MainActivity.this, RecentListFragment.class.getName(), null ) );
fragments.add( Fragment.instantiate( MainActivity.this, EncoderListFragment.class.getName(), null ) );
fragments.add( Fragment.instantiate( MainActivity.this, UpcomingListFragment.class.getName(), null ) );
notifyDataSetChanged();
}
There is a FloatingActionButton on that refreshes the currently selected fragment in the ViewPage. This seems to be firing when activity resumes.
Any ideas on how to prevent this NPE?