Hardcoded string "Button", should use @string resource activity_main.xml
http://stackoverflow.com/questions/8743349/hardcoded-string-row-three-should-use-string-resource
@srting
http://www.moke.tw/wordpress/computer/advanced/252
http://books.gotop.com.tw/L005.aspx?BookId=ACL035100
http://jim690701.blogspot.tw/2012/07/android.html
