Added car instrument simulator

src/main/java/com/levelup/java/exercises/beginner/CarInstrumentSimulator.java

@@ -0,0 +1,155 @@
+package com.levelup.java.exercises.beginner;
+
+/**
+ * This java exercises will demonstrate a solution to the car instrument
+ * simulator problem.
+ * 
+ * @author Justin Musgrove
+ * @see <a href=
+ *      'http://www.leveluplunch.com/java/exercises/car-instrument-simulator/'></a
+ *      >
+ */
+public class CarInstrumentSimulator {
+
+	class FuelGauge {
+
+		final static int MAXIMUM_GALLONS = 15;
+
+		private int gallons;
+
+		public FuelGauge() {
+			gallons = 0;
+		}
+
+		/**
+		 * Constructor should initialize the number of gallons of gas. If the
+		 * gallons is greater than the max it will default to the max.
+		 * 
+		 * TODO: If gallons is greater than max throw GasOverflowException
+		 * 
+		 * @param gallons
+		 */
+		public FuelGauge(int gallons) {
+			if (gallons <= MAXIMUM_GALLONS) {
+				this.gallons = gallons;
+			} else {
+				gallons = MAXIMUM_GALLONS;
+			}
+		}
+
+		public int getGallons() {
+			return gallons;
+		}
+
+		/**
+		 * Method will add one gallon, if gallon is greater than the max for the
+		 * tank then a message will be output.
+		 */
+		public void addGallons() {
+			if (gallons < MAXIMUM_GALLONS) {
+				gallons++;
+			} else {
+				// TODO: see constructor, throw GasOverflowException
+				System.out.println("FUEL OVERFLOWING!!!");
+			}
+		}
+
+		/**
+		 * Burn fuel will reduce the gallons in the tank by 1, if the fuel tank
+		 * is empty then a message will be outputed.
+		 * 
+		 * TODO: Instead of outputting out of fuel, throw a
+		 * GasTankEmptyException
+		 */
+		public void burnFuel() {
+			if (gallons > 0) {
+				gallons--;
+			} else {
+				System.out.println("OUT OF FUEL!!!");
+			}
+		}
+	}
+
+	class Odometer {
+
+		// Constant for the maximum mileage
+		public final int MAXIMUM_MILEAGE = 999999;
+
+		// Constant for the miles-per-gallon
+		public final int MPG = 24;
+
+		private int initialMileage;
+		private int mileage;
+
+		// Field to reference a FuelGauge object
+		private FuelGauge fuelGauge;
+
+		/**
+		 * Constructor
+		 * 
+		 * @param m
+		 *            Initial mileage.
+		 * @param fg
+		 *            A reference to a FuelGauge object.
+		 */
+		public Odometer(int mileage, FuelGauge fuelGauge) {
+			this.initialMileage = mileage;
+			this.mileage = mileage;
+			this.fuelGauge = fuelGauge;
+		}
+
+		/**
+		 * getMileage method
+		 * 
+		 * @returns The mileage.
+		 */
+		public int getMileage() {
+			return mileage;
+		}
+
+		/**
+		 * The addMileage method increments the mileage field. If mileage
+		 * exceeds the maximum amount, it rolls over to 0.
+		 */
+		public void addMileage() {
+
+			if (mileage < MAXIMUM_MILEAGE) {
+				mileage++;
+			} else {
+				mileage = 0;
+			}
+
+			int driven = initialMileage - mileage;
+			if (driven % MPG == 0) {
+				fuelGauge.burnFuel();
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+
+		CarInstrumentSimulator carInstrumentSimulator = new CarInstrumentSimulator();
+
+		FuelGauge fuel = carInstrumentSimulator.new FuelGauge();
+		Odometer odometer = carInstrumentSimulator.new Odometer(0, fuel);
+
+		for (int x = 0; x < FuelGauge.MAXIMUM_GALLONS; x++) {
+			fuel.addGallons();
+		}
+
+		// dive until you can't drive no longer.
+		while (fuel.getGallons() > 0) {
+
+			// add mile driven
+			odometer.addMileage();
+
+			// Display the mileage.
+			System.out.println("Mileage: " + odometer.getMileage());
+
+			// Display the amount of fuel.
+			System.out.println("Fuel level: " + fuel.getGallons() + " gallons");
+			System.out.println("------------------------------");
+		}
+	}
+
+}