Add Units Utility class for Java (#1829)

Units conversion class to convert between commonly used units.

Co-Authored-By: Austin Shalit <austinshalit@gmail.com>

wpilibj/src/main/java/edu/wpi/first/wpilibj/util/Units.java

@@ -0,0 +1,104 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. 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 edu.wpi.first.wpilibj.util;
+
+/**
+ * Utility class that converts between commonly used units in FRC.
+ */
+public final class Units {
+  private static final double kInchesPerFoot = 12.0;
+  private static final double kMetersPerInch = 0.0254;
+  private static final double kSecondsPerMinute = 60;
+
+  /**
+   * Utility class, so constructor is private.
+   */
+  private Units() {
+    throw new UnsupportedOperationException("This is a utility class!");
+  }
+
+  /**
+   * Converts given meters to feet.
+   *
+   * @param meters The meters to convert to feet.
+   * @return Feet converted from meters.
+   */
+  public static double metersToFeet(double meters) {
+    return metersToInches(meters) / kInchesPerFoot;
+  }
+
+  /**
+   * Converts given feet to meters.
+   *
+   * @param feet The feet to convert to meters.
+   * @return Meters converted from feet.
+   */
+  public static double feetToMeters(double feet) {
+    return inchesToMeters(feet * kInchesPerFoot);
+  }
+
+  /**
+   * Converts given meters to inches.
+   *
+   * @param meters The meters to convert to inches.
+   * @return Inches converted from meters.
+   */
+  public static double metersToInches(double meters) {
+    return meters / kMetersPerInch;
+  }
+
+  /**
+   * Converts given inches to meters.
+   *
+   * @param inches The inches to convert to meters.
+   * @return Meters converted from inches.
+   */
+  public static double inchesToMeters(double inches) {
+    return inches * kMetersPerInch;
+  }
+
+  /**
+   * Converts given degrees to radians.
+   *
+   * @param degrees The degrees to convert to radians.
+   * @return Radians converted from degrees.
+   */
+  public static double degreesToRadians(double degrees) {
+    return Math.toRadians(degrees);
+  }
+
+  /**
+   * Converts given radians to degrees.
+   *
+   * @param radians The radians to convert to degrees.
+   * @return Degrees converted from radians.
+   */
+  public static double radiansToDegrees(double radians) {
+    return Math.toDegrees(radians);
+  }
+
+  /**
+   * Converts rotations per minute to radians per second.
+   *
+   * @param rpm The rotations per minute to convert to radians per second.
+   * @return Radians per second converted from rotations per minute.
+   */
+  public static double rotationsPerMinuteToRadiansPerSecond(double rpm) {
+    return rpm * Math.PI / (kSecondsPerMinute / 2);
+  }
+
+  /**
+   * Converts radians per second to rotations per minute.
+   *
+   * @param radiansPerSecond The radians per second to convert to from rotations per minute.
+   * @return Rotations per minute converted from radians per second.
+   */
+  public static double radiansPerSecondToRotationsPerMinute(double radiansPerSecond) {
+    return radiansPerSecond * (kSecondsPerMinute / 2) / Math.PI;
+  }
+}