Don't force public variables to use Hungarian notation (#8774)

People generally have expressed a dislike for the Hungarian notation
used in member variables, especially in examples/templates, and our
styleguide shouldn't be forced on downstream consumers, so this removes
all Hungarian notation from the examples/templates.

There are _some_ benefits to Hungarian for private member variables
(like knowing what's a member vs. local in a PR review) so we'll keep
private member variables the same for now, but public variables should
no longer use Hungarian notation, since it looks much worse. A new PMD
XPath rule has been added to accomplish this goal. Some other
non-compliant variables were fixed for the new rule.

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/Robot.java

@@ -14,8 +14,8 @@ import org.wpilib.framework.TimedRobot;
  * this project, you must also update the Main.java file in the project.
  */
 public class Robot extends TimedRobot {
-  private Command m_autonomousCommand;
-  private final RobotContainer m_robotContainer;
+  private Command autonomousCommand;
+  private final RobotContainer robotContainer;
 
   /**
    * This function is run when the robot is first started up and should be used for any
@@ -24,7 +24,7 @@ public class Robot extends TimedRobot {
   public Robot() {
     // Instantiate our RobotContainer.  This will perform all our button bindings, and put our
     // autonomous chooser on the dashboard.
-    m_robotContainer = new RobotContainer();
+    robotContainer = new RobotContainer();
   }
 
   /**
@@ -54,11 +54,11 @@ public class Robot extends TimedRobot {
   @Override
   public void autonomousInit() {
     // Get selected routine from the SmartDashboard
-    m_autonomousCommand = m_robotContainer.getAutonomousCommand();
+    autonomousCommand = robotContainer.getAutonomousCommand();
 
     // schedule the autonomous command (example)
-    if (m_autonomousCommand != null) {
-      CommandScheduler.getInstance().schedule(m_autonomousCommand);
+    if (autonomousCommand != null) {
+      CommandScheduler.getInstance().schedule(autonomousCommand);
     }
   }
 
@@ -72,8 +72,8 @@ public class Robot extends TimedRobot {
     // use the default command which is ArcadeDrive. If you want the autonomous
     // to continue until interrupted by another command, remove
     // this line or comment it out.
-    if (m_autonomousCommand != null) {
-      m_autonomousCommand.cancel();
+    if (autonomousCommand != null) {
+      autonomousCommand.cancel();
     }
   }
 

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/RobotContainer.java

@@ -27,14 +27,14 @@ import org.wpilib.smartdashboard.SmartDashboard;
  */
 public class RobotContainer {
   // The robot's subsystems and commands are defined here...
-  private final Drivetrain m_drivetrain = new Drivetrain();
-  private final OnBoardIO m_onboardIO = new OnBoardIO(ChannelMode.INPUT, ChannelMode.INPUT);
+  private final Drivetrain drivetrain = new Drivetrain();
+  private final OnBoardIO onboardIO = new OnBoardIO(ChannelMode.INPUT, ChannelMode.INPUT);
 
   // Assumes a gamepad plugged into channel 0
-  private final Joystick m_controller = new Joystick(0);
+  private final Joystick controller = new Joystick(0);
 
   // Create SmartDashboard chooser for autonomous routines
-  private final SendableChooser<Command> m_chooser = new SendableChooser<>();
+  private final SendableChooser<Command> chooser = new SendableChooser<>();
 
   // NOTE: The I/O pin functionality of the 5 exposed I/O pins depends on the hardware "overlay"
   // that is specified when launching the wpilib-ws server on the Romi raspberry pi.
@@ -62,18 +62,18 @@ public class RobotContainer {
   private void configureButtonBindings() {
     // Default command is arcade drive. This will run unless another command
     // is scheduled over it.
-    m_drivetrain.setDefaultCommand(getArcadeDriveCommand());
+    drivetrain.setDefaultCommand(getArcadeDriveCommand());
 
     // Example of how to use the onboard IO
-    Trigger onboardButtonA = new Trigger(m_onboardIO::getButtonAPressed);
+    Trigger onboardButtonA = new Trigger(onboardIO::getButtonAPressed);
     onboardButtonA
         .onTrue(new PrintCommand("Button A Pressed"))
         .onFalse(new PrintCommand("Button A Released"));
 
     // Setup SmartDashboard options
-    m_chooser.setDefaultOption("Auto Routine Distance", new AutonomousDistance(m_drivetrain));
-    m_chooser.addOption("Auto Routine Time", new AutonomousTime(m_drivetrain));
-    SmartDashboard.putData(m_chooser);
+    chooser.setDefaultOption("Auto Routine Distance", new AutonomousDistance(drivetrain));
+    chooser.addOption("Auto Routine Time", new AutonomousTime(drivetrain));
+    SmartDashboard.putData(chooser);
   }
 
   /**
@@ -82,7 +82,7 @@ public class RobotContainer {
    * @return the command to run in autonomous
    */
   public Command getAutonomousCommand() {
-    return m_chooser.getSelected();
+    return chooser.getSelected();
   }
 
   /**
@@ -92,6 +92,6 @@ public class RobotContainer {
    */
   public Command getArcadeDriveCommand() {
     return new ArcadeDrive(
-        m_drivetrain, () -> -m_controller.getRawAxis(1), () -> -m_controller.getRawAxis(2));
+        drivetrain, () -> -controller.getRawAxis(1), () -> -controller.getRawAxis(2));
   }
 }

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/commands/ArcadeDrive.java

@@ -9,9 +9,9 @@ import org.wpilib.command2.Command;
 import org.wpilib.examples.romireference.subsystems.Drivetrain;
 
 public class ArcadeDrive extends Command {
-  private final Drivetrain m_drivetrain;
-  private final Supplier<Double> m_xaxisVelocitySupplier;
-  private final Supplier<Double> m_zaxisRotateSupplier;
+  private final Drivetrain drivetrain;
+  private final Supplier<Double> xaxisVelocitySupplier;
+  private final Supplier<Double> zaxisRotateSupplier;
 
   /**
    * Creates a new ArcadeDrive. This command will drive your robot according to the velocity
@@ -25,9 +25,9 @@ public class ArcadeDrive extends Command {
       Drivetrain drivetrain,
       Supplier<Double> xaxisVelocitySupplier,
       Supplier<Double> zaxisRotateSupplier) {
-    m_drivetrain = drivetrain;
-    m_xaxisVelocitySupplier = xaxisVelocitySupplier;
-    m_zaxisRotateSupplier = zaxisRotateSupplier;
+    this.drivetrain = drivetrain;
+    this.xaxisVelocitySupplier = xaxisVelocitySupplier;
+    this.zaxisRotateSupplier = zaxisRotateSupplier;
     addRequirements(drivetrain);
   }
 
@@ -38,7 +38,7 @@ public class ArcadeDrive extends Command {
   // Called every time the scheduler runs while the command is scheduled.
   @Override
   public void execute() {
-    m_drivetrain.arcadeDrive(m_xaxisVelocitySupplier.get(), m_zaxisRotateSupplier.get());
+    drivetrain.arcadeDrive(xaxisVelocitySupplier.get(), zaxisRotateSupplier.get());
   }
 
   // Called once the command ends or is interrupted.

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/commands/DriveDistance.java

@@ -8,9 +8,9 @@ import org.wpilib.command2.Command;
 import org.wpilib.examples.romireference.subsystems.Drivetrain;
 
 public class DriveDistance extends Command {
-  private final Drivetrain m_drive;
-  private final double m_distance;
-  private final double m_velocity;
+  private final Drivetrain drive;
+  private final double distance;
+  private final double velocity;
 
   /**
    * Creates a new DriveDistance. This command will drive your your robot for a desired distance at
@@ -21,35 +21,35 @@ public class DriveDistance extends Command {
    * @param drive The drivetrain subsystem on which this command will run
    */
   public DriveDistance(double velocity, double inches, Drivetrain drive) {
-    m_distance = inches;
-    m_velocity = velocity;
-    m_drive = drive;
+    distance = inches;
+    this.velocity = velocity;
+    this.drive = drive;
     addRequirements(drive);
   }
 
   // Called when the command is initially scheduled.
   @Override
   public void initialize() {
-    m_drive.arcadeDrive(0, 0);
-    m_drive.resetEncoders();
+    drive.arcadeDrive(0, 0);
+    drive.resetEncoders();
   }
 
   // Called every time the scheduler runs while the command is scheduled.
   @Override
   public void execute() {
-    m_drive.arcadeDrive(m_velocity, 0);
+    drive.arcadeDrive(velocity, 0);
   }
 
   // Called once the command ends or is interrupted.
   @Override
   public void end(boolean interrupted) {
-    m_drive.arcadeDrive(0, 0);
+    drive.arcadeDrive(0, 0);
   }
 
   // Returns true when the command should end.
   @Override
   public boolean isFinished() {
     // Compare distance travelled from start to desired distance
-    return Math.abs(m_drive.getAverageDistanceInch()) >= m_distance;
+    return Math.abs(drive.getAverageDistanceInch()) >= distance;
   }
 }

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/commands/DriveTime.java

@@ -8,10 +8,10 @@ import org.wpilib.command2.Command;
 import org.wpilib.examples.romireference.subsystems.Drivetrain;
 
 public class DriveTime extends Command {
-  private final double m_duration;
-  private final double m_velocity;
-  private final Drivetrain m_drive;
-  private long m_startTime;
+  private final double duration;
+  private final double velocity;
+  private final Drivetrain drive;
+  private long startTime;
 
   /**
    * Creates a new DriveTime. This command will drive your robot for a desired velocity and time.
@@ -21,34 +21,34 @@ public class DriveTime extends Command {
    * @param drive The drivetrain subsystem on which this command will run
    */
   public DriveTime(double velocity, double time, Drivetrain drive) {
-    m_velocity = velocity;
-    m_duration = time * 1000;
-    m_drive = drive;
+    this.velocity = velocity;
+    duration = time * 1000;
+    this.drive = drive;
     addRequirements(drive);
   }
 
   // Called when the command is initially scheduled.
   @Override
   public void initialize() {
-    m_startTime = System.currentTimeMillis();
-    m_drive.arcadeDrive(0, 0);
+    startTime = System.currentTimeMillis();
+    drive.arcadeDrive(0, 0);
   }
 
   // Called every time the scheduler runs while the command is scheduled.
   @Override
   public void execute() {
-    m_drive.arcadeDrive(m_velocity, 0);
+    drive.arcadeDrive(velocity, 0);
   }
 
   // Called once the command ends or is interrupted.
   @Override
   public void end(boolean interrupted) {
-    m_drive.arcadeDrive(0, 0);
+    drive.arcadeDrive(0, 0);
   }
 
   // Returns true when the command should end.
   @Override
   public boolean isFinished() {
-    return (System.currentTimeMillis() - m_startTime) >= m_duration;
+    return (System.currentTimeMillis() - startTime) >= duration;
   }
 }

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/commands/TurnDegrees.java

@@ -8,9 +8,9 @@ import org.wpilib.command2.Command;
 import org.wpilib.examples.romireference.subsystems.Drivetrain;
 
 public class TurnDegrees extends Command {
-  private final Drivetrain m_drive;
-  private final double m_degrees;
-  private final double m_velocity;
+  private final Drivetrain drive;
+  private final double degrees;
+  private final double velocity;
 
   /**
    * Creates a new TurnDegrees. This command will turn your robot for a desired rotation (in
@@ -21,9 +21,9 @@ public class TurnDegrees extends Command {
    * @param drive The drive subsystem on which this command will run
    */
   public TurnDegrees(double velocity, double degrees, Drivetrain drive) {
-    m_degrees = degrees;
-    m_velocity = velocity;
-    m_drive = drive;
+    this.degrees = degrees;
+    this.velocity = velocity;
+    this.drive = drive;
     addRequirements(drive);
   }
 
@@ -31,20 +31,20 @@ public class TurnDegrees extends Command {
   @Override
   public void initialize() {
     // Set motors to stop, read encoder values for starting point
-    m_drive.arcadeDrive(0, 0);
-    m_drive.resetEncoders();
+    drive.arcadeDrive(0, 0);
+    drive.resetEncoders();
   }
 
   // Called every time the scheduler runs while the command is scheduled.
   @Override
   public void execute() {
-    m_drive.arcadeDrive(0, m_velocity);
+    drive.arcadeDrive(0, velocity);
   }
 
   // Called once the command ends or is interrupted.
   @Override
   public void end(boolean interrupted) {
-    m_drive.arcadeDrive(0, 0);
+    drive.arcadeDrive(0, 0);
   }
 
   // Returns true when the command should end.
@@ -57,12 +57,12 @@ public class TurnDegrees extends Command {
     */
     double inchPerDegree = Math.PI * 5.551 / 360;
     // Compare distance travelled from start to distance based on degree turn
-    return getAverageTurningDistance() >= (inchPerDegree * m_degrees);
+    return getAverageTurningDistance() >= (inchPerDegree * degrees);
   }
 
   private double getAverageTurningDistance() {
-    double leftDistance = Math.abs(m_drive.getLeftDistanceInch());
-    double rightDistance = Math.abs(m_drive.getRightDistanceInch());
+    double leftDistance = Math.abs(drive.getLeftDistanceInch());
+    double rightDistance = Math.abs(drive.getRightDistanceInch());
     return (leftDistance + rightDistance) / 2.0;
   }
 }

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/commands/TurnTime.java

@@ -12,10 +12,10 @@ import org.wpilib.examples.romireference.subsystems.Drivetrain;
  * desired rotational velocity and time.
  */
 public class TurnTime extends Command {
-  private final double m_duration;
-  private final double m_rotationalVelocity;
-  private final Drivetrain m_drive;
-  private long m_startTime;
+  private final double duration;
+  private final double rotationalVelocity;
+  private final Drivetrain drive;
+  private long startTime;
 
   /**
    * Creates a new TurnTime.
@@ -25,34 +25,34 @@ public class TurnTime extends Command {
    * @param drive The drive subsystem on which this command will run
    */
   public TurnTime(double velocity, double time, Drivetrain drive) {
-    m_rotationalVelocity = velocity;
-    m_duration = time * 1000;
-    m_drive = drive;
+    rotationalVelocity = velocity;
+    duration = time * 1000;
+    this.drive = drive;
     addRequirements(drive);
   }
 
   // Called when the command is initially scheduled.
   @Override
   public void initialize() {
-    m_startTime = System.currentTimeMillis();
-    m_drive.arcadeDrive(0, 0);
+    startTime = System.currentTimeMillis();
+    drive.arcadeDrive(0, 0);
   }
 
   // Called every time the scheduler runs while the command is scheduled.
   @Override
   public void execute() {
-    m_drive.arcadeDrive(0, m_rotationalVelocity);
+    drive.arcadeDrive(0, rotationalVelocity);
   }
 
   // Called once the command ends or is interrupted.
   @Override
   public void end(boolean interrupted) {
-    m_drive.arcadeDrive(0, 0);
+    drive.arcadeDrive(0, 0);
   }
 
   // Returns true when the command should end.
   @Override
   public boolean isFinished() {
-    return (System.currentTimeMillis() - m_startTime) >= m_duration;
+    return (System.currentTimeMillis() - startTime) >= duration;
   }
 }

wpilibjExamples/src/main/java/org/wpilib/examples/romireference/subsystems/Drivetrain.java

@@ -17,60 +17,60 @@ public class Drivetrain extends SubsystemBase {
 
   // The Romi has the left and right motors set to
   // PWM channels 0 and 1 respectively
-  private final Spark m_leftMotor = new Spark(0);
-  private final Spark m_rightMotor = new Spark(1);
+  private final Spark leftMotor = new Spark(0);
+  private final Spark rightMotor = new Spark(1);
 
   // The Romi has onboard encoders that are hardcoded
   // to use DIO pins 4/5 and 6/7 for the left and right
-  private final Encoder m_leftEncoder = new Encoder(4, 5);
-  private final Encoder m_rightEncoder = new Encoder(6, 7);
+  private final Encoder leftEncoder = new Encoder(4, 5);
+  private final Encoder rightEncoder = new Encoder(6, 7);
 
   // Set up the differential drive controller
-  private final DifferentialDrive m_diffDrive =
-      new DifferentialDrive(m_leftMotor::setThrottle, m_rightMotor::setThrottle);
+  private final DifferentialDrive diffDrive =
+      new DifferentialDrive(leftMotor::setThrottle, rightMotor::setThrottle);
 
   // Set up the RomiGyro
-  private final RomiGyro m_gyro = new RomiGyro();
+  private final RomiGyro gyro = new RomiGyro();
 
   /** Creates a new Drivetrain. */
   public Drivetrain() {
-    SendableRegistry.addChild(m_diffDrive, m_leftMotor);
-    SendableRegistry.addChild(m_diffDrive, m_rightMotor);
+    SendableRegistry.addChild(diffDrive, leftMotor);
+    SendableRegistry.addChild(diffDrive, rightMotor);
 
     // We need to invert one side of the drivetrain so that positive voltages
     // result in both sides moving forward. Depending on how your robot's
     // gearbox is constructed, you might have to invert the left side instead.
-    m_rightMotor.setInverted(true);
+    rightMotor.setInverted(true);
 
     // Use inches as unit for encoder distances
-    m_leftEncoder.setDistancePerPulse((Math.PI * kWheelDiameterInch) / kCountsPerRevolution);
-    m_rightEncoder.setDistancePerPulse((Math.PI * kWheelDiameterInch) / kCountsPerRevolution);
+    leftEncoder.setDistancePerPulse((Math.PI * kWheelDiameterInch) / kCountsPerRevolution);
+    rightEncoder.setDistancePerPulse((Math.PI * kWheelDiameterInch) / kCountsPerRevolution);
     resetEncoders();
   }
 
   public void arcadeDrive(double xaxisVelocity, double zaxisRotate) {
-    m_diffDrive.arcadeDrive(xaxisVelocity, zaxisRotate);
+    diffDrive.arcadeDrive(xaxisVelocity, zaxisRotate);
   }
 
   public void resetEncoders() {
-    m_leftEncoder.reset();
-    m_rightEncoder.reset();
+    leftEncoder.reset();
+    rightEncoder.reset();
   }
 
   public int getLeftEncoderCount() {
-    return m_leftEncoder.get();
+    return leftEncoder.get();
   }
 
   public int getRightEncoderCount() {
-    return m_rightEncoder.get();
+    return rightEncoder.get();
   }
 
   public double getLeftDistanceInch() {
-    return m_leftEncoder.getDistance();
+    return leftEncoder.getDistance();
   }
 
   public double getRightDistanceInch() {
-    return m_rightEncoder.getDistance();
+    return rightEncoder.getDistance();
   }
 
   public double getAverageDistanceInch() {
@@ -83,7 +83,7 @@ public class Drivetrain extends SubsystemBase {
    * @return The current angle of the Romi in degrees
    */
   public double getGyroAngleX() {
-    return m_gyro.getAngleX();
+    return gyro.getAngleX();
   }
 
   /**
@@ -92,7 +92,7 @@ public class Drivetrain extends SubsystemBase {
    * @return The current angle of the Romi in degrees
    */
   public double getGyroAngleY() {
-    return m_gyro.getAngleY();
+    return gyro.getAngleY();
   }
 
   /**
@@ -101,12 +101,12 @@ public class Drivetrain extends SubsystemBase {
    * @return The current angle of the Romi in degrees
    */
   public double getGyroAngleZ() {
-    return m_gyro.getAngleZ();
+    return gyro.getAngleZ();
   }
 
   /** Reset the gyro. */
   public void resetGyro() {
-    m_gyro.reset();
+    gyro.reset();
   }
 
   @Override