If you don't want your fragment to use setRetainInstance(true), then you can add an empty fragment with setRetainInstance(true) to your activity. This is useful since child fragments cannot use setRetainInstance(true).
Example:
java
public class BaseActivity extends Activity {
RetainedFragment retainedFragment;
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
retainedFragment = (RetainedFragment) getFragmentManager().findFragmentByTag("retained_fragment");
if (retainedFragment == null) {
retainedFragment = new RetainedFragment();
getFragmentManager().beginTransaction().add(retainedFragment, "retained_fragment").commit();
}
}
public <T> T getState(String key) {
//noinspection unchecked
return (T) retainedFragment.map.get(key);
}
public void saveState(String key, Object value) {
retainedFragment.map.put(key, value);
}
public boolean has(String key) {
return retainedFragment.map.containsKey(key);
}
public static class RetainedFragment extends Fragment {
HashMap<String, Object> map = new HashMap<>();
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
}
}Then, in your fragment, you can cast getActivity() to your Activity class and use saveState(String, Object) and getState(String) to save your list.
There are other discussions on this which can be found at the following locations:
What to do on TransactionTooLargeException
android.os.TransactionTooLargeException on Nougat (Accepted answer suggests setRetainInstance(true)).