android - onSaveInstanceState () and onRestoreInstanceState ()

Question

I'm trying to save and restore the state of an Activity using the methods onSaveInstanceState() and onRestoreInstanceState().

The problem is that it never enters the onRestoreInstanceState() method. Can anyone explain to me why this is?

Answer 1

Usually you restore your state in onCreate(). It is possible to restore it in onRestoreInstanceState() as well, but not very common. (onRestoreInstanceState() is called after onStart(), whereas onCreate() is called before onStart().

Use the put methods to store values in onSaveInstanceState():

protected void onSaveInstanceState(Bundle icicle) {
  super.onSaveInstanceState(icicle);
  icicle.putLong("param", value);
}

And restore the values in onCreate():

public void onCreate(Bundle icicle) {
  if (icicle != null){
    value = icicle.getLong("param");
  }
}