example.java

public interface Subsystem {
  /**
   * Called once when the robot enters the disabled state.
   */
  void initDisabled();
  
  /**
   * Called once when the robot enters the teleop state.
   */
  void initTeleop();
  
  /**
   * Called roughly every 20ms, or at 50Hz, while in the disabled state.
   */
  void runDisabled();
  
  /**
   * Called roughly every 20ms, or at 50Hz, while in the teleop state.
   */
  void runTeleop();
  
  // The display method isn't necessary, but I like it. To each their own.
  // You should call this in your robots periodic methods. Or not. Whatever you want.
  // I use this so that the other functional code doesn't get overly cluttered with
  // print statements, but you will likely need them anyway for debugging.
  /**
   * Called to display things via the Dashboard or via print commands. Not necessary to use.
   */
  void display();
}

// Example usage
public class DriveTrain implements Subsystem {
  private Talon left, right;
  public DriveTrain() {
    // The ports under the Constants file are just where the Talons (or whatever speed controller)
    // are plugged into the RoboRIO.
    left = new Talon(Constants.DT_LEFT_PORT);
    right = new Talon(Constants.DT_RIGHT_PORT);
  }
  
  // well, don't drive in disabled. :)
  public void initDisabled() {
    left.set(0.0);
    right.set(0.0);
  }
  
  public void initTeleop() {
    // don't need to do anything here
  }
  
  public void runDisabled() {
    // don't need to do anything here
  }
  
  public void runTeleop() {
    // Controls can be whatever you want them to be. This is just an example.
    double forwardSpeed = Robot.joystick.getLeftJoystickY(); // between -1 and 1
    double turnRightValue = Robot.joystick.getRightTrigger(); // between 0 and 1
    double turnLeftValue = Robot.joystick.getLeftTrigger(); // between 0 and 1
    
    // I will warn you that these signs may be off. you may need to adjust these if you use this.
    // Again, this is example code, and you should write your own controls to your driver's preference!
    left.set(clamp(forwardSpeed - turnRightValue, -1.0, 1.0));
    right.set(clamp(forwardSpeed - turnLeftValue, -1.0, 1.0));
  }
  
  /**
   * Clamps a value to a certain range.
   */
  private static double clamp(double value, double minLimit, double maxLimit) {
    return Math.max(minLimit, Math.min(value, maxLimit));
  }
  
  public void display() {
    SmartDashboard.putNumber("DT Left Speed", left.get());
    SmartDashboard.putNumber("DT Right Speed", right.get());
  }
}

public class Robot extends IterativeRobot() {
  // Called once when the robot turns on
  public void disabledInit() {
    
  }
}