This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Welcome to the Javaranch. You must have overlooked our naming policy on the way in. In short, your name must be a real-sounding first and last name separated by a space. As for your question, when you do input or output redirection on a command line, the command interpreter (or shell in *nix) is what does the redirection. You either have to exec to a shell (i.e. "bash command < inputfile", just a wild guess, I dont know the exact syntax) so it can do the indirection or use Java to read the file and input it to the Process object's input stream.
You could try that. You could also try executing the shell and passing your program as an argument to the shell (as I detailed before). Here is an article that details the problems with Runtime.exec and the workarounds.
subject: Running external application with stdin as argument