Please help. Cannot find symbol Error!

Question

I have been working on this code for days now. It keeps coming up with errors. The error says cannot find symbol. I will bold the areas that say that. I got it down to 23 from 42 but now I have no idea what the problem is. any help is greatly appreciated!! I only added a couple of them mainly because it is overwhelming. I can add the rest of someone replies. Thank you again. Oh and the Classpath is set right. I am compiling from the desktop where I have the file also. That was the first thing I checked after reading other threads related to this issue. :O)
import javax.swing.*;
import java.awt.event.*;
public class InventoryPart4 extends JFrame
     private JTextArea text;
     private Inventory inv;
     private int view;
     public InventoryPart4() {
          super("Product");
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // quit if the window is closed
          view = 0; // current one showing
          Product product;
          inv = new Inventory(4);
          product = new Product(1, "Salad", 3, 4.95); here
          inv.add(product, 0);
product = new Product(2, "Dressing", 6, 3.00); here          
inv.add(product, 1);
product = new Product(3, "Bacon Bits", 2, 1.75);*here*
          inv.add(product, 2);
product = new Product(4, "Croutons", 1, 1.75); here
          inv.add(product, 3);
          // sort
          inv.sort();
          // output
          for (int i = 0; i < 4; i++) {
               System.out.println(inv.get(i));
          // total val
          System.out.printf("Total=$%.2f", inv.totalValue());
          //gui
          JPanel panel = new JPanel();
          panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
          text = new JTextArea(10,50);
          text.setEditable(false);
          panel.add(text);
          showProduct();
          JButton next = new JButton("Next");
here          next.addProduct(new Product() {
               public void actionPerformed(ActionEvent e) {
                    if (view < inv.size()-1) view++;
                    else view = 0;
                    showProduct();
          panel.add(next);
          getContentPane().add(panel);
     // view an item
     public void showProduct() {
          text.setText("Product Details:\n");
          text.append(inv.get(view).toString()+"\n");
          text.append(String.format
                    ("Value of all the Contents: $%.2f", inv.totalValue()));
     public static void main(String args [])
          InventoryPart4 invt = new InventoryPart4();
          invt.pack();
          invt.setVisible(true);
     } //end main
} // end class InventoryPart1
class Product {
private int ProductItem;
private int ProductStock;
private double ProductPrice;
public Product(int item, int stock, double price) {
ProductItem = item;
ProductStock = stock;
ProductPrice = price;
} //end three-argument constructor
// set Product Item
public void setProductItem(int item) {
ProductItem = item; here
} //end method set Product Item
//return Product Item
public int getsProductItem() {
return productItem;
} //end method get product Item
//set Product Stock
public void setProductStock(int stock) {
productStock = stock;
} //end method set Product Stock
//return Product Stock
public int getProductStock() {
return productStock;
} //end method get Product Stock
public void setProductPrice(double price) {
productPrice = price;
} //end method setproductPrice
//return Product Price
public double getProductPrice() {
return ProductPrice;
} //end method get Product Price
//calculate inventory value
public double value() {
return productPrice * productStock;
}// end method get productPrice and productStock
@Override
public String toString() {
return String.format("item=%3d units=%d price=%.2f value=%.2f",
productItem, productStock, productPrice, value());
}//end class Product
class Inventory {
     private Product[] list;
     // constructor
     public Inventory(int size) {
          list = new Product[size];
     // complete value
     public double totalValue() {
          double val = 0.0;
          for (int i = 0; i < list.length; i++) {
               val += list.value();
          return val;
     // add an item
     public void add(Product i, int p) {
          list[p] = i;
     // get an item
     public Product get(int i) {
          return list[i];
     // sort by name
     public void sort() {
          // bubble sort
          int n = list.length;
          for (int search = 1; search < n; search++) {
               for (int i = 0; i < n-search; i++) {
                    if (list[i].getProductItem().compareToIgnoreCase(list[i+1].getProductItem()) > 0) {
                         // swap
                         Product temp = list[i];
                         list[i] = list[i+1];
                         list[i+1] = temp;
     public int size() {
          return list.length;
//extended class
class Contents extends Product {
     private String Contents;
     // constructor
     public Contents(int item, String name, int units, double price) {
          super(item,name,units, price);
          this.contents = contents;
     // getter
     public String getContents() {
          return Contents;
     // total value with the 5% fee
     public double value() {
          return super.value()*1.05;
     // just the 5% fee
     public double fee() {
          return super.value()*0.05;
     // setter
     public void setContents(String contents) {
          this.contents = contents;
     public String toString()
          return super.toString() + String.format(" fee=%.2f contents=%-20s",
                    fee(), contents);

Answer 1

The error says cannot find symbol.It says more than that. It says what symbol it cannot find, and it points to the line of code where the symbol was used.
          product = new Product(1, "Salad", 3, 4.95); *here*So it can't find a class called Product with an accessible constructor Product(int, String, int, double).
product = new Product(2, "Dressing", 6, 3.00); *here*          
inv.add(product, 1);
product = new Product(3, "Bacon Bits", 2, 1.75);*here*
          inv.add(product, 2);
product = new Product(4, "Croutons", 1, 1.75); *here*
          inv.add(product, 3);Ditto.
          JButton next = new JButton("Next");
*here*          next.addProduct(new Product() {JButton doesn't have an addProduct() method.
public Product(int item, int stock, double price) {This constructor doesn't match the constructor you are calling above, and there are no other constructors.
ProductItem = item; *here*You must have a typo. But don't use inital capitals on field names: use them only on class names.
return productItem;Here is evidence that you have a typo. Java is case-sensitive. Either the field is caled 'ProductItem' or it is called 'productItem', not both.
          // bubble sortDo you have to do this for the homework? Bubble sort is never used in real code except by people who don't know what they're talking about. Use Collections.sort().
          super(item,name,units, price);You should be getting a compile error here too. Ther is no such constructor for Product.
          return Contents;And here.