Version 3_ Change Internal Representation of Weight to Newtons.java

/* PRESET CODE BEGIN - NEVER TOUCH CODE BELOW */
public class Main {
    public static void main(String[] args) {
      // Create a vehicle that can handle 10,000 kilograms weight
      System.out.println("Creating a vehicle with a 10,020kg maximum load.");
      Vehicle vehicle = new Vehicle(10020.0);
      // Add a few boxes
      System.out.println("Add box #1 (500kg) : " + vehicle.addBox(500.0));
      System.out.println("Add box #2 (250kg) : " + vehicle.addBox(250.0));
      System.out.println("Add box #3 (5000kg) : " + vehicle.addBox(5000.0));
      System.out.println("Add box #4 (4000kg) : " + vehicle.addBox(4000.0));
      System.out.println("Add box #5 (300kg) : " + vehicle.addBox(300.0));
      System.out.println("Add box #5 (270kg) : " + vehicle.addBox(270.0));
      // Print out the final vehicle load
      System.out.println("Vehicle load is " + vehicle.getLoad() + " kg");
    }
  }
  /* PRESET CODE END - NEVER TOUCH CODE ABOVE */
  class Vehicle {
      private double load;    // the current weight of the vehicle's cargo
      private double maxLoad; // the vehicle's maximum cargo weight limit
      public Vehicle(double max_load) {
          load = 0;
          maxLoad = kiloToNewts(max_load);
      }
      public double getLoad() {
          return newtsToKilo(load);
      }
      public double getMaxLoad() {
          return newtsToKilo(maxLoad);
      }
      public boolean addBox(double weight) {
          weight = kiloToNewts(weight);
          if (load + weight > maxLoad) {
              return false;
          } else {
              load += weight;
              return true;
          }
      }
      private double kiloToNewts(double weight) {
          return (weight * 9.8);
      }
      private double newtsToKilo(double weight) {
          return (weight / 9.8);
      }
  }