From the TinyOS tutorial at your link:
Supported distributions are (hardy, intrepid, jaunty, karmic)
All of these Ubuntu releases are end of life and are no longer supported by updates. You are using Ubuntu 14.04 which is not supported by the TinyOS package repository that is shown in the tutorial at your link.
Instead I followed the instructions from ...
When you add a different source in /etc/apt/sources.list; you would also have to run the following command in terminal:
sudo apt-get update
This retrieves the new list of packages and knows what are the different packages available for installation and where to download it from.
Once you have run the above command, you may proceed with installation of ...
Install TinyOS in Ubuntu 14.04
Visit TinyOS (TinyProd) Debian Development Repository and follow these instructions:
Tell apt about the TinyProd Signing Key.
wget -O - http://tinyprod.net/repos/debian/tinyprod.key | sudo apt-key add -
Add the two new lines to /etc/apt/sources.list.d/tinyprod-debian.list:
echo "deb ...
Generally speaking this kind of error is caused by the Java CLASSPATH not being set correctly.
Most software will come with instructions or a shell script or an installer as to how to set it. If not try setting that variable to the base directory containing .class files, or to the location of the jar file.