$ sudo apt-get install sun-java6-jdk
报错：E: Package 'sun-java6-jdk' has no installation candidate
修改/etc/apt/source.list(其为只读，取消只读用 $ sudo chmod go+w sources.list )
添加deb http://us.archive.ubuntu.com/ubuntu/ hardy multiverse ，保存后$ sudo apt-get update
再试$ sudo apt-get install sun-java6-jdk
安装到configuring sun-java6-jre 时OK点不到，需要按下tab。
如果此时你把页面关了，则你想再进入配置页就要输入：sudo apt-get -f install 这是查询安装的所有依赖包。否则你想install或者reinstall都不行，会报：ia32-sun-java6 gsfonts-x11 Unmet dependencies这些错误。
最后用java -version测试下。
Ubuntu 12.04安装JDK见：
http://www.cnblogs.com/beyonding1983/archive/2012/11/08/2759757.html
https://help.ubuntu.com/community/Java
-
IMPORTANT choose the java you installed as default
$ sudo update-alternatives --config java $ sudo update-alternatives --config javac $ sudo update-alternatives --config mozilla-javaplugin.so $ sudo update-alternatives --config javaws
设置JAVA_HOME:
If you want this environment variable available to all users and on system start then you can add the following to /etc/profile.d/java.sh (create it if necessary):
export JDK_HOME=/usr/lib/jvm/yourjdk
export JAVA_HOME=/usr/lib/jvm/
yourjdk
Then in a terminal run:
sudo chmod +x /etc/profile.d/java.sh
source /etc/profile.d/java.sh