Using Encoders to Correct Drive

[Becca334]

I need help with using encoders to keep a robot going straight, basically adjusting the speeds of Victors based on encoder rates to make sure one motor doesn't slack behind another.

I know that this is possible with PID loops but I have not found a single Java implementation of PID for this task (and I really don't understand conceptually how PID works either)

We're using the RobotDrive class with tankDrive for driving with 4 motors and 2 encoders (one per 2 motors on each side).