Java Threads

[Aaron V]

So I have experience in programming - but one thing I haven't really looked into in detail are threads - I've always just let the compiler deal with them for me. I understand the concept of threads. The different parts of a programmer running essentially at the same time (alternating fast enough so that it doesn't really make a difference). I just don't understand what parts of a program constitutes as a difference thread. I've written a few additional classes for organisational purposes - do they have any effect?

Basically my main problem is that I need to pulse solenoids. It's simple to set it open or closed based on other input, but I don't know how to use time as an input. I figure I need threads because I don't want to stop everything else in the code.

Finally I've both seen the wait() function in the object class and the delay() function in the Timer class - I'm not sure which is better to use and which thread it effects.