Ubuntu 9.10以上版本中，Ubuntu去除了对sun-java5-jdk的支持，如果必须安装sun-java5-jdk。那么可以采用如下方法：
1.编辑/etc/apt/sources.list文件，将安装源更改为Ubuntu 9.04的安装源为：
deb http://archive.Ubuntu.com/ubuntu/ jaunty main restricted universe multiverse
deb http://archive.Ubuntu.com/ubuntu/ jaunty-security main restricted universe multiverse
deb http://archive.Ubuntu.com/ubuntu/ jaunty-updates main restricted universe multiverse
deb http://archive.Ubuntu.com/ubuntu/ jaunty-proposed main restricted universe multiverse
deb http://archive.Ubuntu.com/ubuntu/ jaunty-backports main restricted universe multiverse
deb-src http://archive.Ubuntu.com/ubuntu/ jaunty main restricted universe multiverse
deb-src http://archive.Ubuntu.com/ubuntu/ jaunty-security main restricted universe multiverse
deb-src http://archive.Ubuntu.com/ubuntu/ jaunty-updates main restricted universe multiverse
deb-src http://archive.Ubuntu.com/ubuntu/ jaunty-proposed main restricted universe multiverse
2. sudo apt-get install sun-java5-jdk