External application input/output

Question

Hi.
I'm trying to communicate with an external shell program - this takes input, goes away and does stuff which includes generating a lot of output, and then requires more input.
I need to know when the process is ready for input again, before I send it anything - otherwise a straightforward send would attempt to give input to the application while it's still processing and outputting data, and this would be ignored.
What I have already is an input monitor thread that repeatedly reads from the process' input stream and outputs what it sees. This works fine, but it stops when it reads the line or even character where input is required, rendering it useless for my task.
So, essentially, how do I detect when user input is required, without inherently locking the process until some is given?
Cheers,
Rob

Answer 1

Yep - I would think so.
If there is a particular bit of string that the program outputs before it stops for an input, then you could check the string that you have read in.
If you really want to do it perfectly, you can write a class (say ProcessMonitor) which extends Thread and monitors your process. It can implement the Observable interface and update any observers when it perceives that the process requires an input. That way your "shoddy" interfaceing code is segregated from the rest of your system.