Good news!
Here's the output of "update-alternatives --config java":
There are 5 alternatives which provide `java'.
Selection Alternative
-----------------------------------------------
1 /usr/bin/gij-wrapper-4.0
*+ 2 /usr/lib/jvm/java-gcj/bin/java
3 /etc/alternatives/kaffe-system/bin/java
4 /usr/lib/jvm/java-1.5.0-sun/jre/bin/java
5 /usr/lib/jvm/java-6-sun/jre/bin/java
Press enter to keep the default[*], or type selection number: 5
Using `/usr/lib/jvm/java-6-sun/jre/bin/java' to provide `java'.
So I chose number five. And then:
kone:/home/saturnine# java -version
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)
That looked good, so I tried "./jin" and it works!
Thank you very much for all the help, rickh!