尝试在 Ubuntu 14.04 上安装 Java 8
$ sudo add-apt-repository ppa:webupd8team/java
gpg: keyring `/tmp/tmpkt42czb_/secring.gpg' created
gpg: keyring `/tmp/tmpkt42czb_/pubring.gpg' created
gpg: requesting key EEA14886 from hkp server keyserver.ubuntu.com
gpgkeys: key 7B2C3B0889BF5709A105D03AC2518248EEA14886 can't be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0