No Java virtual machine could be found

Which release are you using?

I do not believe Sarge had Java (unless it was gjc), but java from the Blackdown project has returned to etch and sid.

If you run Sarge you can go to:
http://www.blackdown.org/java-linux/java2-status/jdk1.4-status.html#debs

If you have installed an appropriate version of JRE but still get that error, you need to find out what environment variable to set and set it in the appropriate script (.bash_profile or .bashrc).

You set an environment variable via something like:
export BLAH=/usr/sbin/blahblah

Unless the software tells you what environment variable it is expecting, it is really rather difficult to figure out what to do.

Here are a few things to try:

1. update-alternatives --config java
This should bring up a dialog asking you to select the Java VM to use as default. Without looking at the scripts, I'm hoping it will create 'symlinks' which make programs looking for 'java' automatically look at whatever Java VM you've installed.

If that doesn't work then things get more complicated:

2. Create the symlink yourself:
a. identify where your java software has been installed:
where java*
I'm on WinDos at the moment so I can't check easily, but on Debian this would probably be something like /usr/lib/sun-jre2/. Since you installed a different VM, I can't even try to guess what the name is.
b. create a symlink to that directory:
ln -s /usr/lib/sun-jre2 /usr/lib/java
There are at least 3 options for Java on Debian and they all have different directory names - however, most programs are expecting a directory named 'java' which simply doesn't exist. This command creates a 'symlink' named 'java' which actually points to the real Java directory, in this case '/usr/lib/sun-jre2'.

See if that runs.. if not:
c. edit your '.bashrc' file to create the environment variable "JAVA_HOME" (yes, the case does matter). You can append to .bashrc by doing something like this:
i. cd (switches to your user's home directory)
ii. cp .bashrc .bashrc-orig (makes a copy of .bashrc just in case you make a mistake)
iii. echo 'export JAVA_HOME="/usr/lib/java"' >> .bashrc
iv. Log out of your X windows and log in again - this updates your environment variables. There may be a way to update without logging out, but I don't know it - I'm very X illiterate.

If it STILL doesn't work then maybe the VM you installed isn't up to the task - install the SUN JVM following the instructions on the link I posted previously.