What methods can be used to retain and restore the state of an Activity in Android?

In Android, the following methods are used to retain and restore the Activity state:

• onSaveInstanceState(Bundle outState) — called before the Activity is destroyed, where you can save the state (e.g., form field values) into a Bundle object.

• onRestoreInstanceState(Bundle savedInstanceState) or receiving the Bundle in onCreate(Bundle savedInstanceState) — where the saved data is restored.

• ViewModel — an architecture component that preserves data during configuration changes (e.g., screen rotation) and is independent of the Activity lifecycle.

• Saving data to persistent storage (SharedPreferences, database) — for longer-term storage.

Example of saving state:

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putString("key", editText.getText().toString());
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState != null) {
        String text = savedInstanceState.getString("key");
        editText.setText(text);
    }
}