How to prevent custom views from losing state across screen orientation changes

Question

I\'ve successfully implemented onRetainNonConfigurationInstance() for my main Activity to save and restore certain critical components across screen orientation

Answer 1

To augment other answers - if you have multiple custom compound views with the same ID and they are all being restored with the state of the last view on a configuration change, all you need to do is tell the view to only dispatch save/restore events to itself by overriding a couple of methods.

class MyCompoundView : ViewGroup {

    ...

    override fun dispatchSaveInstanceState(container: SparseArray) {
        dispatchFreezeSelfOnly(container)
    }

    override fun dispatchRestoreInstanceState(container: SparseArray) {
        dispatchThawSelfOnly(container)
    }
}

For an explanation of what is happening and why this works, see this blog post. Basically your compound view's children's view IDs are shared by each compound view and state restoration gets confused. By only dispatching state for the compound view itself, we prevent their children from getting mixed messages from other compound views.