Before you run the program you have to make a couple of changes.
First, you can't call the class Temperature; you have to call it
Hello, because that's the name of the file, and the name of the class
has to be the same as the name of the file. This is a dumb rule that
the otherwise sensible Java people came up with during a
caffeine-induced frenzy. Nevertheless, it can be accomodated easily
enough by making sure the name of the class is Hello.
IMPORTANT: If you ever forget this rule, and the class name is
different from the file name, confusing things will happen. Avoid