엑티비티 변환 시 데이터를 저장합니다.

SharedPreferences prefs = getSharedPreferences("PrefName", MODE_PRIVATE);

SharedPreferences.Editor editor = prefs.edit();

editor.putString(KEY_MY_PREFERENCE, text);

editor.commit();

엑티비티를 다시 실행하였을 때 데이터를 불러옵니다.

SharedPreferences prefs = getSharedPreferences("PrefName", MODE_PRIVATE);

String text = prefs.getString(KEY_MY_PREFERENCE, "");