頑張るぞ！
References
- https://www.ralismark.xyz/2019/01/07/bluehid-2.html
- https://github.com/ralismark/bluehid/blob/master/app/src/main/java/io/github/ralismark/bluehid/MainActivity.java
- https://developer.android.google.cn/reference/java/util/concurrent/Executor?hl=ja
- http://yan-note.blogspot.com/2012/10/android-spinner.html