On UNIX (i.e. troi) J++ does not exist. Instead, to use Java you need to use JDK, which is Sun's Java compiler (which uses the standard, by the way, the rest of the world uses, except Microsoft and J++). JDK also exists for Windows and is freeware. Look at the Sun Java Site for more details.
JDK does not have an IDE (integrated development environment) like J++. This means there is no nice program that let's you edit files, compile, and run, all from the same program (which is what an IDE is). Rather, you have to do things separately yourself using smaller tools (which is what UNIX is usually like).
To use pico just type pico and the name of the file you want to edit. This is the same editor used for pine, so you are probably somewhat used to it.
Class1.java
run
javac Class1.javaThis will create a .class file for that file. You need a .class file for each .java file.
Class1
then
I would call
java Class1to run my code. Note that for compiling you include the extension, but for running you do not.