having trouble with Array calculations

import java.util.Arrays;    
 
 
public class Inventory3 {
 
    //main method begins execution of the Java Application and tells the computer to initiate inventory entries
    public static void main(String args[]) {
        DVD dvd = null;
        Inventory inventory = new Inventory();        
 
        System.out.println("\nKevin's DVD Inventory\n");
 
        dvd = new DVD(5, 3, 21.06, "Zule");
        inventory.add(dvd);   
 
        dvd = new DVD(7, 15, 29.99, "Transformers");
        inventory.add(dvd);   
 
        dvd = new DVD(12, 9, 15.99, "Toy Soldiers");
        inventory.add(dvd);   
 
        dvd = new DVD(13, 10, 12.99, "Ghostbusters");
        inventory.add(dvd);   
 
        dvd = new DVD(21, 16, 19.99, "Punisher");
        inventory.add(dvd);   
 
        dvd = new DVD(5, 20, 59.99, "Matrix trilogy");
        inventory.add(dvd);   
 
        dvd = new DVD(27, 8, 14.99, "The Incredibles");
        inventory.add(dvd);   
 
        inventory.display();		
        }  // end method dvd
 
    } // end method main
 
// end class Inventory2
 
 
 
class DVD implements Comparable{
    private int no;
    private int copies;
    private double price;
    private String name;
 
    DVD(int no, int copies, double price, String name) {
        this.no     = no;
        this.copies = copies;
        this.price  = price;
        this.name   = name;
    }
 
    public String getName() {
        return name;
    }
 
    public double value() {
        return price * copies;    
    }
    
    public double fee() {
        return value * .05;
    }
 
    public int compareTo(Object object) {
        return name.compareTo(((DVD) object).getName());
    }
 
    public String toString() {
        return String.format("no=%2d   copies=%2d   price=$%5.2f   name=%-15s   value=$%,2.2f   fee=%$,.2f",
                              no, copies, price, name, value(), fee());
    }
 
} // end class DVD
 
 
class Inventory{ 
    
    private DVD[] dvds;
    private int numDVDs;
    private int value;
 
    Inventory() {
        dvds = new DVD[10];
        numDVDs = 0;
    }
 
    public void add(DVD dvd) {
      dvds[numDVDs] = dvd;
      ++numDVDs;
      sort();
    }
 
    public double totalValue() {
        double total = 0;
        for (int i=0; i<dvds.length; i++) {
            total += dvd[i].getcopies * dvd[i].getprice;
        }
        return total;
        
    }
    
 
    private void sort() {
        Arrays.sort(dvds, 0, numDVDs);
    }
 
    public void display() {
      System.out.println("\nKevin's inventory contains " + numDVDs + " DVD Titles\n");
      for (int i = 0; i < numDVDs; i++)
          System.out.printf("%3d  %s\n", i, dvds[i]);
        System.out.printf("\nTotal inventory value is %.2f\n\n", totalValue());
    }
 
} // end class Inventory

                                  

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