How to install Java on Kubuntu?

[Gerald I. Evenden]

I have tried to get some Java stuff sent by another person to run on my 
system.  In the latest case I got a file that program 'file' shows as:

file Speed*
SpeedTest4-linux: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), 
for GNU/Linux 2.2.5, dynamically linked (uses shared libs), not stripped

So I set it as executable and:

./Speed*
Unable to find a supported JDK or JRE version. Version 1.3.1 or higher is 
required.
Check your installation and use +javahome to specify the JDK or JRE location

I cannot find any documentation on JDK, JRE or +javahome.

I few weeks ago I tried the "hello world" from a tutorial website but had 
troubles there also.  Doing search on synaptic yields a multipage listing of 
crap related to jave but I have no idea where to start.

Is there any cookbook for setting up Java on Kubuntu?

Thanks in advance.

PS: I am not sure that the person sending me the test knows much more about 
Java than I do---which nothing.  I'm just an old C programmer that knows 
nuttin about this new fangled stuff.

-- 
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist