I have have a FragmentActivity
with two tabs which are ListFragment
s. Each ListFragment
has a callback.
An example of a callback
The callback is associated inside of the onAttach(...) method
OnStatusUpdateListener mStatusUpdateCallback;
public interface OnStatusUpdateListener {
public void onStatusUpdate();
}
@Override
public void onAttach(Activity activity) {
Log.d(TAG, "onAttach");
super.onAttach(activity);
try {
mStatusUpdateCallback = (OnStatusUpdateListener)activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString() + " must implement OnStatusUpdateListener");
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
Log.d(TAG, "onCreate");
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
Later on, I communicate with the FragmentActivity
by this callback which works fine normally.
Within the ListFragment
, I have an ImageButton
that will call a DialogFragment
which also has a callback. This callback is implemented in my ListFragment
and is what triggers the callback that is null
public void onStatusOption() {
Log.d(TAG, "onStatusOption");
// Update stuff
// Here is where mStatusUpdateCallback is null after rotate
mStatusUpdateCallback.onStatusUpdate();
}
The problem is that if I ever rotate the phone while the application is running, mStatusUpdateCallback becomes null. This of course means I cannot execute the callback. Does anyone know how to fix this?
What I've tried
According to https://stackoverflow.com/a/6029070/935779 it appears that a new reference to OnStatusUpdateListener
may have been created so I cannot reference the old, but doesn't offer a solution.
I've also tried retaining the state as per https://stackoverflow.com/a/6787393/935779, but I can't save a reference to a callback as far as I can tell.
I also would really rather not do the android:configChanges="orientation|keyboardHidden"
method since that just seems like a hack and my layout changes in landscape.
Stacktrace
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.blug.blah.Fragment.StatusFragment.onStatusOption(StatusFragment.java:197)
at com.blug.blah.MyActivity.onStatusOption(MyActivity.java:243)
at com.blug.blah.Dialog.StatusOptionDialog$1$1.onClick(StatusOptionDialog.java:108)
at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:158)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4627)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
When configuration of the Activity
being destroy and recreates.
When Configuration
of the phone is changed the method onConfigurationChange
called.
So you can initialize your Callbacks
in onConfigurationChange