恢复活动状态

Question

For restoring the state of the activity after it is recreated (for instance after the screen-orientation change) I implemented onSaveInstanceState() and onRestoreInstanceState(). It is simple to save/restore simple information like int, double etc. But what about saving/restoring objects like Timer?

Answer 1

You cannot store "live" objects (like db connections) in the Activity arguments or saved instance data. Those mechanisms are designed so that the application can be completely stopped, so it only works with things that can be "serialized" and later restored.

What you can do is use fragments. If you add a fragment without UI (check here , look for “Adding a fragment without a UI”) and call on it setRetainInstance(true) the fragment will get reattached to the activity, surviving any configuration change.

Hope it helps. (Remember you can use fragments with old Android versions by using the support package)