問題：安裝oracle-java8-installer按照如下指南失敗：
How To Install Java with Apt-Get on Ubuntu 16.04[https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-get-on-ubuntu-16-04]
解決：
sudo add-apt-repository ppa:ts.sch.gr/ppa
sudo apt-get update
sudo apt-get install oracle-java8-installer