Java Inheritance Multilevel Hierarchy Class

// Extend LegoBlockWeight to include shipping costs.
// Start with LegoBlock.
class LegoBlock {
  private double width;
  private double height;
  private double depth;

  // construct clone of an object
  LegoBlock(LegoBlock ob) { // pass object to constructor
    width = ob.width;//from  www  .  j av  a 2  s .c  o  m
    height = ob.height;
    depth = ob.depth;
  }

  // constructor used when all dimensions specified
  LegoBlock(double w, double h, double d) {
    width = w;
    height = h;
    depth = d;
  }

  // constructor used when no dimensions specified
  LegoBlock() {
    width = -1;  // use -1 to indicate
    height = -1; // an uninitialized
    depth = -1;  // box
  }

  // constructor used when cube is created
  LegoBlock(double len) {
    width = height = depth = len;
  }

  // compute and return volume
  double volume() {
    return width * height * depth;
  }
}

// Add weight.
class LegoBlockWeight extends LegoBlock {
  double weight; // weight of box

  // construct clone of an object
  LegoBlockWeight(LegoBlockWeight ob) { // pass object to constructor
    super(ob);
    weight = ob.weight;
  }

  // constructor when all parameters are specified
  LegoBlockWeight(double w, double h, double d, double m) {
    super(w, h, d); // call superclass constructor
    weight = m;
  }    

  // default constructor
  LegoBlockWeight() {
    super();
    weight = -1;
  }

  // constructor used when cube is created
  LegoBlockWeight(double len, double m) {
    super(len);
    weight = m;
  }
}

// Add shipping costs
class Shipment extends LegoBlockWeight {
  double cost;

  // construct clone of an object
  Shipment(Shipment ob) { // pass object to constructor
    super(ob);
    cost = ob.cost;
  }

  // constructor when all parameters are specified
  Shipment(double w, double h, double d,
            double m, double c) {
    super(w, h, d, m); // call superclass constructor
    cost = c;
  }    

  // default constructor
  Shipment() {
    super();
    cost = -1;
  }

  // constructor used when cube is created
  Shipment(double len, double m, double c) {
    super(len, m);
    cost = c;
  }
}
  
public class Main {
  public static void main(String args[]) {
    Shipment shipment1 = 
               new Shipment(10, 20, 15, 10, 3.41);
    Shipment shipment2 =
               new Shipment(2, 3, 4, 0.76, 1.28);

    double vol;

    vol = shipment1.volume();
    System.out.println("Volume of shipment1 is " + vol);
    System.out.println("Weight of shipment1 is "
                        + shipment1.weight);
    System.out.println("Shipping cost: $" + shipment1.cost);
    System.out.println();

    vol = shipment2.volume();
    System.out.println("Volume of shipment2 is " + vol);
    System.out.println("Weight of shipment2 is "
                        + shipment2.weight);
    System.out.println("Shipping cost: $" + shipment2.cost);
  }
}