Simple example of a FRC robot program that drives a robot with encoders during autonomous.

EncoderExample.java

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008. All Rights Reserved.                             */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

package org.lunatecs316.frc;

import edu.wpi.first.wpilibj.CounterBase.EncodingType;
import edu.wpi.first.wpilibj.Encoder;
import edu.wpi.first.wpilibj.RobotDrive;
import edu.wpi.first.wpilibj.SimpleRobot;

public class EncoderExample extends SimpleRobot {

    // Constants
    public static final double kDistancePerRevolution = 18.84;  // guestimate from your code
    public static final double kPulsesPerRevolution = 1024;     // for an AS5145B Magnetic Encoder
    public static final double kDistancePerPulse = kDistancePerRevolution / kPulsesPerRevolution;

    //
    // Encoder Wiring:
    //
    // Left Encoder A Channel  -> DIO 1, Module 1
    // Left Encoder B Channel  -> DIO 2, Module 1
    // Right Encoder A Channel -> DIO 3, Module 1
    // Right Encoder B Channel -> DIO 4, Module 1
    //
    // Details on WPILib Encoder class: http://wpilib.screenstepslive.com/s/3120/m/7912/l/85770-measuring-rotation-of-a-wheel-or-other-shaft-using-encoders
    //
    private Encoder leftEncoder = new Encoder(1, 2, false, EncodingType.k4X);
    private Encoder rightEncoder = new Encoder(3, 4, true, EncodingType.k4X);    // Count direction reversed

    // Two motor drive
    private RobotDrive drive = new RobotDrive(1, 2);

    /**
     * Initialize the robot.
     */
    public void robotInit() {
        leftEncoder.setDistancePerPulse(kDistancePerPulse);
        rightEncoder.setDistancePerPulse(kDistancePerPulse);

        leftEncoder.start();
        rightEncoder.start();

        resetEncoders();
    }

    /**
     * This function is called once each time the robot enters autonomous mode.
     */
    public void autonomous() {
        // Drive forwards for 50 units
        resetEncoders();
        do {
            drive.arcadeDrive(0.5, 0.0);
        } while (getAverageEncoderPosition() < 50.0);
        drive.arcadeDrive(0.0, 0.0);
    }

    private double getAverageEncoderPosition() {
        return (leftEncoder.getDistance() + rightEncoder.getDistance()) / 2;
    }

    private void resetEncoders() {
        leftEncoder.reset();
        rightEncoder.reset();
    }
}