title: How to reject a change in onSharedPreferenceChanged() listener
body: <p>The <code>onSharedPreferenceChanged()</code> listener does not have a boolean type to return, as the <code>onPreferenceChanged()</code> listener has. </p>
  
  <p>So how can one reject a change after validation?</p>
  
  <p>The only way that occurs to me is to keep all shared preferences stored in local variables and if the validation fails, restore the value from the local variable, if it passes update the local variable.</p>
  
  <p>Is this doing double work? Is there a built-in mechanism for reject?</p>