There should be a way to handle operating system signals, especially UNIX's SIGINT.

Consider a command interpreter written in Java and running on any support Java
platform.  Essentially all operating systems provide a way to interrupt the
currently running program.  A Java command interpreter needs the ability to
catch this interrupt request and abort operations in progress, and then return
to the main command-reading loop.  Thus, handling this signal and aborting
operations must not require closing the input device.

Such a mechanism should also support handling POSIX-specific and other operating
system-specific signals as much as possible.  SIGTSTP and SIGCONT would be
especially important for a command interpreter.

Obviously any solution that effectively requires putting the terminal device into
raw mode and emulating terminal-generated signals would be completely unacceptable.
Any solution must integrate with the operating system's signal handling capabilities.