Inventory Program Part 6 - Please Help

Question

My last assignment is due in about two hours and I am completely lost. I have been trying to figure out how to add functionality to my JButtons all week.
I have added the following buttons but they do not work: save, delete, modify, save, search, add.
I also need to add a company logo. I hope someone can please help me understand.
Here is my current code:
public class DVD {
     protected int itemNum;     // item number
     protected String name;     // item name
     protected int unit;          // number of units of the item
     protected double price;     // price of each unit
     public DVD() {}          // Default constructor
     public DVD(int itemNum, String name, int unit, double price) {
          // Constructor with input
          this.itemNum = itemNum;
          this.name = name;
          this.unit = unit;
          this.price = price;
     // Getter and Setter methods
     public void setItemNum(int itemNum) {
          this.itemNum = itemNum;
     public int getItemNum() {
          return itemNum;
     public void setName(String name) {
          this.name = name;
     public String getName() {
          return name;
     public void setUnit(int unit) {
          this.unit = unit;
     public int getUnit() {
          return unit;
     public void setPrice(double price) {
          this.price = price;
     public double getPrice() {
          return price;
     // Get the value of the inventory
     public double calculateInventory() {
          return unit * price;
     // Get the value of all inventory
     public static double calculateEntireInventory(DVD [] prod) {
          double sum = 0;
          for (int i = 0; i < prod.length; i++)
               sum += prod.getUnit() * prod[i].getPrice();
          return sum;
     // Sort inventory by name
     public static Movie [] sortInventory(Movie [] prod) {
     boolean doMore = true;
while (doMore) {
doMore = false; // last pass over array
for (int i=0; i<prod.length-1; i++) {
if (prod[i].getName().compareTo(prod[i+1].getName()) > 0) {
Movie temp = prod[i]; prod[i] = prod[i+1]; prod[i+1] = temp;
doMore = true;
     return prod;
public class Movie extends DVD{
     //instant variable
     protected String dvdTitle;
public Movie(int itemNum, String name, int unit, double price, String dvdTitle) {
     super(itemNum, name, unit, price);
     this.dvdTitle = dvdTitle;
public String getdvdTitle() {
          return dvdTitle;
     // Get the value of the inventory
     public double calculateInventory(DVD[] dvd) {
          double sum = 0;
          for (int i = 0; i < dvd.length; i++)
               sum += 0.05* dvd[i].getUnit() * dvd[i].getPrice();
          return sum;
public double calculateRestockFee(){
     return price*0.05;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
import java.text.DecimalFormat;
import javax.swing.Icon;
import javax.swing.ImageIcon;
public class Inventory extends JApplet {
     private JLabel itemNumLabel = new JLabel("Item Number: ");
     private JTextField itemNum = new JTextField();
     private JLabel itemNameLabel = new JLabel("Category: ");
     private JTextField itemName = new JTextField();
     private JLabel unitLabel = new JLabel("Number of Units: ");
     private JTextField unit = new JTextField();
     private JLabel priceLabel = new JLabel("Unit Price: ");
     private JTextField price = new JTextField();
     private JLabel dvdTitleLabel = new JLabel("DVD Title: ");
     private JTextField dvdTitle = new JTextField();
     private JLabel rfLabel = new JLabel("Restocking Fee");
     private JTextField rfValue = new JTextField();
     private JLabel inventoryLabel = new JLabel("Inventory value: ");
     private JTextField inventoryValue = new JTextField();
     private JLabel totalValue = new JLabel();
     private JButton previous = new JButton("Previous");
     private JButton next = new JButton("Next");
     private JButton last = new JButton("Last");
     private JButton first = new JButton("First");
     private JButton add = new JButton("Add");
     private JButton delete = new JButton("Delete");
     private JButton modify = new JButton("Modify");
     private JButton save = new JButton("Save");
     private JButton search = new JButton("Search");
     private JLabel totalInventory = new JLabel();
     private Movie[] DVDArray = null;
     private int current = 0;
     private int total = 0;
     class ButtonListener implements ActionListener {
          public void actionPerformed(ActionEvent e) {
               JButton button = (JButton) e.getSource();
               if (button == previous) current = (current + total - 1) % total;
               if (button == next) current = (current + 1) % total;
               if (button == last) current = (current = 5) % total;
               if (button == first) current = (current =0) % total;
               if (button == modify) itemName.setVisible(true);
     private void display() {
          Movie movie = DVDArray[current];
          DecimalFormat df=new DecimalFormat("$#.00");
          itemNum.setText(movie.getItemNum()+""); itemNum.setEditable(false);
          itemName.setText(movie.getName()); itemName.setEditable(false);
          unit.setText(movie.getUnit()+""); unit.setEditable(false);
          price.setText(df.format(movie.getPrice())); price.setEditable(false);
          dvdTitle.setText(movie.getdvdTitle()); dvdTitle.setEditable(false);
          rfValue.setText(df.format(movie.calculateRestockFee())); rfValue.setEditable(false);
          inventoryValue.setText(df.format(movie.calculateInventory())); inventoryValue.setEditable(false);
          totalValue.setText("The total inventory value is " + df.format(DVD.calculateEntireInventory(DVDArray)));
     final JLabel label; // logo
//JLabel constructor for logo
Icon logo = new ImageIcon("C:/logo.jpg"); // load logo
label = new JLabel(logo); // create logo label
label.setToolTipText("Company Logo"); // create tooltip
     public void init() {
          DVDArray = new Movie [6];
          // Add DVD items into the list
          DVDArray[0] = new Movie (15, "Action", 65,12.00,"Frequency");
          DVDArray[1]= new Movie(33, "Comedy", 12, 21.00, "Norbit");
          DVDArray[2] = new Movie(13, "Disney",33,14.00,"Flubber");
          DVDArray[3] = new Movie(22, "Drama", 48, 18.00,"Citizens Kane");
          DVDArray[4] = new Movie(47, "Horror", 42, 19.00,"Pycho");
          DVDArray[5] = new Movie(26, "Sci-Fi", 27, 26.00,"The Abyss");
total = 6;
current = 0;
ButtonListener buttonListener = new ButtonListener();
previous.addActionListener(buttonListener);
next.addActionListener(buttonListener);
last.addActionListener(buttonListener);
first.addActionListener(buttonListener);
add.addActionListener(buttonListener);
delete.addActionListener(buttonListener);
modify.addActionListener(buttonListener);
save.addActionListener(buttonListener);
search.addActionListener(buttonListener);
JPanel up = new JPanel();
up.setLayout(new GridLayout(7,2));
up.add(itemNumLabel); up.add(itemNum);
up.add(itemNameLabel); up.add(itemName);
up.add(dvdTitleLabel); up.add(dvdTitle);
up.add(unitLabel); up.add(unit);
up.add(priceLabel); up.add(price);
up.add(rfLabel); up.add(rfValue);
up.add(inventoryLabel); up.add(inventoryValue);
display();
JPanel middle = new JPanel();
middle.setLayout(new FlowLayout());
middle.add(previous); middle.add(next);middle.add(last);middle.add(first);
middle.add(add);middle.add(delete);middle.add(modify);middle.add(search);
middle.add(save);
JPanel down = new JPanel();
down.setLayout(new BorderLayout());
down.add(BorderLayout.CENTER, totalValue);
JPanel all = new JPanel();
all.setLayout(new BoxLayout(all, BoxLayout.Y_AXIS));
all.add(up);
all.add(down);
all.add(middle);
Container cp = getContentPane();
cp.add(BorderLayout.NORTH, all);
public static void main(String args []) {
JApplet applet = new Inventory();
JFrame frame = new JFrame("DVD Inventory");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
Container cp=frame.getContentPane();
cp.add(applet);
frame.setSize(600,330);
applet.init();
frame.setVisible(true);
// Icon logo = new ImageIcon(getResource( "logo.gif" ) );
} //end main
} // end class Inventory                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

Your code has some good spots and some bad spots or problems, and I'll try to hit on some of the more obvious problems (the ones that I can see immediately) so that you can try to fix it.
1) Your DVD class overall looks pretty good until we get to the end. The method public static double calculateEntireInventory(DVD[] prod) shouldn't be part of the DVD class since it has nothing to do with an individual DVD (which is what this class is all about) and everything to do with a collection of DVDs. You should move this to another class, a non-GUI Inventory class.
2) The method public static Movie[] sortInventory(Movie[] prod) also shouldn't be in your DVD class for the same reason as noted above, and also because it deals with Movie objects which are objects that descend from DVD. The parent really shouldn't have to depend on the child class to function, and leaving this in would likely break your code at some time or another. Again, put this in a non-GUI Inventory class. You probably should use a DVD parameter, not a Movie parameter. Another option is to have your DVD and Movie classes implement the Comparable interface, since if you do this, sorting any collection of these is a breeze by using Arrays.sort(...) or Collections.sort(...).
3) Again (starting to sound like a broken record) the method public double calculateInventory(DVD[] dvd) shouldn't be part of the Movie class for the very same reasons noted above.
4) You need to create a non-GUI Inventory class, shoot, you can call it NonGuiInventory if you'd like (though I'd call it Inventory and call the GUI class GuiInventory) that has all the important functionality that the GUI will display. This class holds a collection of DVDs (or Movies), has an int index that points to the current Movie of interest, has a next() method that advances this index and returns the next Movie in the collection (or the first if you're at the last), has a previous() method that does the opposite, has a first() method that sets the index to zero and returns the first Movie in the collection, a last() method that advances the index to the size of the collection - 1 and returns this Movie, and has a sort method that sorts the collection. You can even have add(Movie) and a remove(Movie) methods here. By separating this functionality from the GUI, you are able to simplify your task by dividing and conquering.
5) Finally you can display all this with your InventoryGUI class that uses the above class as its model, displaying the current Movie that is pointed to by the Inventory's index, that when the next() method is called gets the Movie returned by it and displays it.
Note that if you go this route, you'll need to do some major re-writes of the GUI class, but it will improve your program greatly.
HTH and good luck