$SIG{INT} = sub {
   open my $fh, ">PleaseStop" or warn "open(PleaseStop): $!";
}

##</code><code>##

my $outcome = qx/java MyClass param1 param2 param3 ... /;

##</code><code>##

# When it's time to call... call call_command
sub call_command {
   my $command = shift;
   my ($pid, $rd, $wt);
   {
      local $SIG{INT} = 'IGNORE';
      $pid = open2($rd, $wt, $command); # From IPC::Open2
   }
   my $outcome = join "", <$rd>;
   waitpid $pid, 0;
   return $outcome;
}