The API contains the classes and packages available for any Java program. Swing is the recommended interface to use for developing java programs with graphical interfaces.
Swing is installed on teaching linux machines.
Local documention for JFC is available. Requires the compiled class files to check the program. You can expect non-trivial java programs to run faster using kaffe. Kaffe is installed on linux teaching machines and the free source is mirrored at elangen university . Look at Sun's Java page javasoft for much more information.