isStateSaved
Returns true
if the FragmentManager's state has already been saved by its host. Any operations that would change saved state should not be performed if this method returns true. For example, any popBackStack() method, such as popBackStackImmediate or any FragmentTransaction using commit instead of commitAllowingStateLoss will change the state and will result in an error.
Return
true if this FragmentManager's state has already been saved by its host