In this paper we describe a way to save and restore the state of a running Java
program. We achieve this on the language level, without modifying the Java
virtual machine, by instrumenting the programmer's original code with a
preprocessor. The automatically inserted code saves the runtime information when
the program requests state saving and reestablishes the program's runtime state
on restart.  The current preprocessor prototype is used in a mobile agent
scenario to offer transparent agent migration for Java based mobile agents, but
could generally be used to save and reestablish the execution state of any Java
program.