Restoring state of TextView after screen rotation?

If you want to force your TextView to save its state you must add freezesText attribute:

<TextView 
     ... 
     android:freezesText="true" />

From documentation on freezesText :

If set, the text view will include its current complete text inside of its frozen icicle in addition to meta-data such as the current cursor position. By default this is disabled; it can be useful when the contents of a text view is not stored in a persistent place such as a content provider

In order to retain data on orientation change you need to implement the two methods:

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // Read values from the "savedInstanceState"-object and put them in your textview
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    // Save the values you need from your textview into "outState"-object
    super.onSaveInstanceState(outState);
}