Hello Right now im doing some lab tasks from my textbook but this one i quite do

Question

Hello

Right now im doing some lab tasks from my textbook but this one i quite don`t get. I have doing some work for a while but more work that i do then more mistakes too. Now I am totally confused in the head of it. If there is someone who know about this I would appreciate to get help because im stuck and very confused to figure out this...

Task:

I have taken the example of three classes that were referred to so that there will be no misunderstandings under me here:

//********************************************************************
// DVDCollection.java
// Represents a collection of DVD movies.
//********************************************************************

import java.text.NumberFormat;

public class DVDCollection
{
private DVD[] collection;
private int count;
private double totalCost;

//-----------------------------------------------------------------
// Constructor: Creates an initially empty collection.
//-----------------------------------------------------------------
public DVDCollection ()
{
collection = new DVD[100];
count = 0;
totalCost = 0.0;
}

//-----------------------------------------------------------------
// Adds a DVD to the collection, increasing the size of the
// collection array if necessary.
//-----------------------------------------------------------------
public void addDVD (String title, String director, int year,
double cost, boolean bluRay)
{
if (count == collection.length)
increaseSize();

collection[count] = new DVD (title, director, year, cost, bluRay);
totalCost += cost;
count++;
}

//-----------------------------------------------------------------
// Returns a report describing the DVD collection.
//-----------------------------------------------------------------
public String toString()
{
NumberFormat fmt = NumberFormat.getCurrencyInstance();

String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ";
report += "My DVD Collection ";

report += "Number of DVDs: " + count + " ";
report += "Total cost: " + fmt.format(totalCost) + " ";
report += "Average cost: " + fmt.format(totalCost/count);

report += " DVD List: ";

for (int dvd = 0; dvd < count; dvd++)
report += collection[dvd].toString() + " ";

return report;
}

//-----------------------------------------------------------------
// Increases the capacity of the collection by creating a
// larger array and copying the existing collection into it.
//-----------------------------------------------------------------
private void increaseSize ()
{
DVD[] temp = new DVD[collection.length * 2];

for (int dvd = 0; dvd < collection.length; dvd++)
temp[dvd] = collection[dvd];

collection = temp;
}
}

//********************************************************************
// DVD.java
// Represents a DVD video disc.
//********************************************************************

import java.text.NumberFormat;

public class DVD
{
private String title, director;
private int year;
private double cost;
private boolean bluRay;

//-----------------------------------------------------------------
// Creates a new DVD with the specified information.
//-----------------------------------------------------------------
public DVD (String title, String director, int year, double cost,
boolean bluRay)
{
this.title = title;
this.director = director;
this.year = year;
this.cost = cost;
this.bluRay = bluRay;
}

//-----------------------------------------------------------------
// Returns a string description of this DVD.
//-----------------------------------------------------------------
public String toString()
{
NumberFormat fmt = NumberFormat.getCurrencyInstance();

String description;

description = fmt.format(cost) + " " + year + " ";
description += title + " " + director;

if (bluRay)
description += " " + "Blu-Ray";

return description;
}
}

//********************************************************************
// Movies.java
// Demonstrates the use of an array of objects.
//********************************************************************

public class Movies
{
//-----------------------------------------------------------------
// Creates a DVDCollection object and adds some DVDs to it. Prints
// reports on the status of the collection.
//-----------------------------------------------------------------
public static void main (String[] args)
{
DVDCollection movies = new DVDCollection();

movies.addDVD ("The Godfather", "Francis Ford Coppala", 1972, 24.95, true);
movies.addDVD ("District 9", "Neill Blomkamp", 2009, 19.95, false);
movies.addDVD ("Iron Man", "Jon Favreau", 2008, 15.95, false);
movies.addDVD ("All About Eve", "Joseph Mankiewicz", 1950, 17.50, false);
movies.addDVD ("The Matrix", "Andy & Lana Wachowski", 1999, 19.95, true);

System.out.println (movies);

movies.addDVD ("Iron Man 2", "Jon Favreau", 2010, 22.99, false);
movies.addDVD ("Casablanca", "Michael Curtiz", 1942, 19.95, false);

System.out.println (movies);
}
}

Explanation / Answer

please rate

//********************************************************************
//DVDCollection.java
//Represents a collection of DVD movies.
//********************************************************************


import java.text.NumberFormat;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

class DVDCollection {
    List<DVD> collection;
    private int count;
    private double totalCost;

    // -----------------------------------------------------------------
    // Constructor: Creates an initially empty collection.
    // -----------------------------------------------------------------
    public DVDCollection() {
        collection = new LinkedList<DVD>();
        count = 0;
        totalCost = 0.0;
    }

    // -----------------------------------------------------------------
    // Adds a DVD to the collection, increasing the size of the
    // collection array if necessary.
    // -----------------------------------------------------------------
    public void addDVD(String title, String director, int year, double cost,
            boolean bluRay) {
        /*
        * if (count == collection.length)
            increaseSize();
        */
        collection.add( new DVD(title, director, year, cost, bluRay) );
        totalCost += cost;
        count++;
    }

    // -----------------------------------------------------------------
    // Returns a report describing the DVD collection.
    // -----------------------------------------------------------------
    public String toString() {
        NumberFormat fmt = NumberFormat.getCurrencyInstance();

        String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ";
        report += "My DVD Collection ";

        report += "Number of DVDs: " + count + " ";
        report += "Total cost: " + fmt.format(totalCost) + " ";
        report += "Average cost: " + fmt.format(totalCost / count);

        report += " DVD List: ";

        /*
        * for (int dvd = 0; dvd < count; dvd++)
        *
        *    report += collection[dvd].toString() + " ";
        */
        Iterator<DVD> dvd = collection.listIterator();
        while(dvd.hasNext()){
            report += dvd.next().toString()+" ";
        }
        return report;
    }

    // -----------------------------------------------------------------
    // Increases the capacity of the collection by creating a
    // larger array and copying the existing collection into it.
    // -----------------------------------------------------------------
    /* Function not needed
    private void increaseSize() {
        DVD[] temp = new DVD[collection.length * 2];

        for (int dvd = 0; dvd < collection.length; dvd++)
            temp[dvd] = collection[dvd];

        collection = temp;
    }
    */
}

// ********************************************************************
// DVD.java
// Represents a DVD video disc.
// ********************************************************************


import java.text.NumberFormat;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

class DVD {
    private String title, director;
    private int year;
    private double cost;
    private boolean bluRay;

    // -----------------------------------------------------------------
    // Creates a new DVD with the specified information.
    // -----------------------------------------------------------------
    public DVD(String title, String director, int year, double cost,
            boolean bluRay) {
        this.title = title;
        this.director = director;
        this.year = year;
        this.cost = cost;
        this.bluRay = bluRay;
    }

    // -----------------------------------------------------------------
    // Returns a string description of this DVD.
    // -----------------------------------------------------------------
    public String toString() {
        NumberFormat fmt = NumberFormat.getCurrencyInstance();

        String description;

        description = fmt.format(cost) + " " + year + " ";
        description += title + " " + director;

        if (bluRay)
            description += " " + "Blu-Ray";

        return description;
    }
}

// ********************************************************************
// Movies.java
// Demonstrates the use of an array of objects.
// ********************************************************************


import java.text.NumberFormat;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

public class Movies {
    // -----------------------------------------------------------------
    // Creates a DVDCollection object and adds some DVDs to it. Prints
    // reports on the status of the collection.
    // -----------------------------------------------------------------
    public static void main(String[] args) {
        DVDCollection movies = new DVDCollection();

        movies.addDVD("The Godfather", "Francis Ford Coppala", 1972, 24.95,true);
        movies.addDVD("District 9", "Neill Blomkamp", 2009, 19.95, false);
        movies.addDVD("Iron Man", "Jon Favreau", 2008, 15.95, false);
        movies.addDVD("All About Eve", "Joseph Mankiewicz", 1950, 17.50, false);
        movies.addDVD("The Matrix", "Andy & Lana Wachowski", 1999, 19.95, true);

        System.out.println(movies);

        movies.addDVD("Iron Man 2", "Jon Favreau", 2010, 22.99, false);
        movies.addDVD("Casablanca", "Michael Curtiz", 1942, 19.95, false);

        System.out.println(movies);
    }
}

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