https://qooah.com/2014/07/06/%e5%82%b3%e8%81%9e-google-%e7%82%ba-android-l-%e6%b8%ac%e8%a9%a6%e5%8f%a6%e4%b8%80%e5%a5%97%e8%99%9b%e6%93%ac%e6%8c%89%e9%8d%b5/