Fragment activity crashes on screen rotate

Question

I have a simple fragment activity. In the onCreate() method, I simply add a fragment. The code is posted below. However, each time I rotate the screen, system will call onCr

Answer 1

Your Fragment shouldn't have constructors because of how the FragmentManager instantiate it. You should have a newInstance() static method defined and pass any parameters via arguments (bundle)

For example:

public static final MyFragment newInstance(int title, String message)
{
    MyFragment fragment = new MyFragment();
    Bundle bundle = new Bundle(2);
    bundle.putInt(EXTRA_TITLE, title);
    bundle.putString(EXTRA_MESSAGE, message);
    fragment.setArguments(bundle);
    return fragment ;
}

And read these arguments at onCreate:

@Override
public void onCreate(Bundle savedInstanceState)
{
    title = getArguments().getInt(EXTRA_TITLE);
    message = getArguments().getString(EXTRA_MESSAGE);

    //...

}

This way if detached and re-attached the object state can be stored through the arguments, much like bundles attached to Intents.