JAVA code to drive straight using H-drive

[RobOTies]

We are a second year team and are using 6" omni wheels in an H-drive configuration for the first time. Our robot tends to veer left when we are trying to drive straight ahead during auto and teleop, and I was wondering if anyone would be willing to share any code ideas that would help with this issue. We have a gyro as well, but not sure how to effectively utilize it for this purpose. We have already tried making sure the gear boxes that are attached to CIM motors are as identical as possible.

Go robots! Thank you!!