SharedPreferences物件

SharedPreferences物件
偏好設定SharedPreferences可用來紀錄資料
在Activity重新啟動後，可回復關閉前資訊 
通常在"onPasue"寫入參數，在"onRseume"讀取參數

寫入參數
    SharedPreferences settings = getSharedPreferences ("DATA", 0);
    SharedPreferences.Editor PE = settings.edit();
    PE.putString("data_str", "hello");
    PE.putInt("date_int", 100);
    PE.commit();

    or

    SharedPreferences settings = getSharedPreferences ("DATA", 0);
    settings.edit()
        .putString("data_str", "hello");
        .putInt("date_int", 100);
        .commit();

讀取參數
    SharedPreferences settings = getSharedPreferences("DATA", 0);
    // 如果讀不到值，就會回傳後面設定的參數
    String str = settings.getString("data_str", "null");
    int i = settings.getInt("date_int", 0);