package com.oreilly.tiger.ch02;

import java.util.Iterator;

public class NumberBox<N extends Number> extends Box<N> {

  public NumberBox() {
    super();
  }
 
  // Sum everything in the box
  public double sum() {
    double total = 0;
    for (Iterator<N> i = contents.iterator(); i.hasNext(); ) {
      total = total + i.next().doubleValue();
    }
    return total;
  }  

  public static <A extends Number> double sum(Box<A> box1,
                                              Box<A> box2) {
    double total = 0;
    for (Iterator<A> i = box1.contents.iterator(); i.hasNext(); ) {
      total = total + i.next().doubleValue();
    }
    for (Iterator<A> i = box2.contents.iterator(); i.hasNext(); ) {
      total = total + i.next().doubleValue();
    }
    return total;
  }
}