installing java

[Markus Schönhaber]

mike williams wrote:
> in the terminal,when i enter "su",it asks for the password which i type,but
> it tells me authentication failed,how can i fix this problem?

This is not a Problem, this is by design. By default you can't login as root 
and therefore su won't work. Use
sudo <command>
to execute command as root. If you want a root shell, do something like
sudo bash
or better
sudo -i

https://help.ubuntu.com/community/RootSudo

Regards
  mks