import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.text.*;
import java.lang.*;
 
public class Inventory2 extends JFrame
{
	private JLabel cdNameLabel; // name label 
	private JLabel artistLabel; // item number label 
	private JLabel nstockLabel; // units in stock label 
	private JLabel priceLabel; // price each label 
	private JLabel itemLabel; // item number label 
	private JTextField cdNameField; // name display 
	private JTextField artistField; // artist display 
	private JFormattedTextField nstockField; // units in stock display 
	private JFormattedTextField priceField; // price each display 
	private JTextField itemField; // item number display 
	private NumberFormat nstockFormat; // format field and parse numbers 
	private NumberFormat priceFormat; // format field and parse numbers 
	private JButton btnAdd; // first button 
	private JButton btnPrev; // previous button 
	private JButton btnNext; // next button 
	private JButton btnDel; // last button 
	private JButton btnFirst; // first button
	private JButton btnLast; // last button
	private JButton btnModify; // modify button
	private JButton btnSave; // save button
	private JButton btnSearch; // search button
	private JPanel buttonJPanel; // JPanle to hold buttons 
	private JPanel fieldJPanel; // JPanel to hold labels and displays 
	private JPanel fontJPanel; // JPanel to display logo 
	private int currCD; 
	private double total = 0; // variable for total inventory 
	private JList Inventorylist; // JList to take place of old array
	private DefaultListModel listModel;
	private JScrollPane jScrollPanel;  
	private float Invtotal = .00f;
 
	public Inventory2() // create class and method to perform GUI build 
	{ 
		initComponents(); 
	} 
 
	private void initComponents() 
	{ 
		// create label names 
		cdNameLabel = new JLabel("CD Name:"); 
		artistLabel = new JLabel("Artist:");
		nstockLabel = new JLabel("In Stock:"); 
		priceLabel = new JLabel("Each Item Cost:$"); 
		itemLabel = new JLabel("Item Number:"); 
 
 
		// initial fields
		cdNameField = new JTextField(25);
		cdNameField.setEditable(true);
		artistField = new JTextField(15);
		artistField.setEditable(true);
		nstockField = new JFormattedTextField(nstockFormat);
		nstockField.setEditable(true);
		nstockField.setColumns(5);
		priceField = new JFormattedTextField(priceFormat);
		priceField.setEditable(true);
		priceField.setColumns(5);
		itemField = new JTextField(4);
		itemField.setEditable(true);
 
		// JList
		jScrollPanel = new JScrollPane();
		Inventorylist = new JList(); 
		currCD = 0;
 
 
		// buttons 
		btnAdd = new JButton(); 
		btnNext = new JButton(); 
		btnPrev = new JButton(); 
		btnDel = new JButton();
		btnLast = new JButton();
		btnFirst = new JButton();
		btnModify = new JButton(); 
		btnSave = new JButton();
		btnSearch = new JButton();
 
		getContentPane().setLayout(new FlowLayout());
 
		setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 
 
		// place textFields and labels
 
		//artist
		artistLabel.setText("Artist"); 
		getContentPane().add(artistLabel); 
 
		artistField.setMinimumSize(new Dimension(70,20)); 
		artistField.setPreferredSize(new Dimension(70,20));
		getContentPane().add(artistField); 
 
		// cd name
		cdNameLabel.setText("CD Name"); 
		getContentPane().add(cdNameLabel); 
 
		cdNameField.setMinimumSize(new Dimension(70,20)); 
		cdNameField.setPreferredSize(new Dimension(70,20));
		getContentPane().add(cdNameField);
 
		// copies in stock
		nstockLabel.setText("Copies In Stock"); 
		getContentPane().add(nstockLabel); 
 
		nstockField.setMinimumSize(new Dimension(5,20)); 
		nstockField.setPreferredSize(new Dimension(5,20));
		getContentPane().add(nstockField); 
 
		//price of cd
		priceLabel.setText("Price"); 
		getContentPane().add(priceLabel); 
 
		priceField.setMinimumSize(new Dimension(20,20)); 
		priceField.setPreferredSize(new Dimension(20,20));
		getContentPane().add(priceField); 
 
		//item number of cd
		itemLabel.setText("Item Number"); 
		getContentPane().add(itemLabel); 
 
		itemField.setMinimumSize(new Dimension(5,20)); 
		itemField.setPreferredSize(new Dimension(5,20));
		getContentPane().add(itemField); 
 
 
		// add listeners
 
		btnAdd.setText("Add");
		btnAdd.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnAdd);
 
		// PREVIOUS
		btnPrev.setText("Previous");
		btnPrev.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnPrevActionPerformed(evt);
			}
		});
		getContentPane().add(btnPrev);
 
		// NEXT
		btnNext.setText("Next");
		btnNext.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnNext);
 
		// SEARCH
		btnSearch.setText("Search");
		btnSearch.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnSearch);
 
		// FIRST
		btnFirst.setText("First");
		btnFirst.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnFirst);
 
		// LAST
		btnLast.setText("Last");
		btnLast.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnLast);
 
		// MODIFY
		btnModify.setText("Modify");
		btnModify.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnModify);
 
		// SAVE
		btnSave.setText("Save");
		btnSave.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnSave);
 
		// DELETE
		btnDel.setText("Delete");
		btnDel.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnDel);
 
 
		// new Jlist model
		listModel = new DefaultListModel();
		Inventorylist.setModel(listModel);
 
		jScrollPanel.setViewportView(Inventorylist);
 
		getContentPane().add(jScrollPanel);
 
		pack();
	}// close
 
 
		private void btnAddActionPerformed(ActionEvent evt)
		{
			// Create cd to add
			CdwArtist newCD = new CdwArtist();
			newCD.setArtist(artistField.getText());
			newCD.setName(cdNameField.getText());	
			newCD.setItemno(Integer.parseInt(itemField.getText()));
			newCD.setNstock(Integer.parseInt(nstockField.getText()));
			newCD.setPrice(Float.parseFloat(priceField.getText()));
 
			// Add cd to list
			listModel.addElement(newCD);
			currCD = listModel.size()-1;  // sets currCD to added index
 
 
			// Clear the text fields after add
			artistField.setText(null);
			cdNameField.setText(null);	
			itemField.setText(null);
			nstockField.setText(null);
         priceField.setText(null);
 
			}// end ADD
 
		private void btnPrevActionPerformed(ActionEvent evt)
		{
			// Grab Previous cd 
			CdwArtist newCD = (CdwArtist) listModel.get( currCD-- );
			newCD.setArtist(artistField.getText());
			newCD.setName(cdNameField.getText());	
			newCD.setItemno(Integer.parseInt(itemField.getText()));
			newCD.setNstock(Integer.parseInt(nstockField.getText()));
			newCD.setPrice(Float.parseFloat(priceField.getText()));		
 
			}// end PREV
 
		// run it
		public static void main(String args[])
		{
		java.awt.EventQueue.invokeLater(new Runnable()
			{
			public void run()
				{
				new Inventory2().setVisible(true);
			   }
			});
		}
 
} // close class

import java.util.*;
import java.text.*; 
import java.lang.Comparable;
 
 
public class Compactdisk implements Comparable
{// begin class
 
	//InventoryCD class has 5 fields
	public String name; //  Name of cd
	public float price; // price of cd
	public int itemno; // item number of cd
	public int nstock; // how many units in stock	
	private int i; // cd counter for array
	public float value; // value for single cd inventory
 
 
 
	//Compact disk class constructor
	public Compactdisk()
 
		// 4 fields need to be set up
		{ 
		name = "";
		price = .00f;
		itemno = 0;
		nstock = 0;
		i = 0;
		value = .00f;
		}
 
		// set values
	   public void setName(String diskName)
	   {
	   name = diskName;
	   }
		public void setPrice(float cdPrice)
	   {
	   price = cdPrice;
	   }
		public void setItemno(int cdItemno)
	   {
	   itemno = cdItemno;
	   }
		 public void setNstock(int cdStock)
	   {
	   nstock = cdStock;
	   }
		public void setValue(float cdValue)
		{
		value = cdValue;
		}
		public void seti(int Count)
		{
		i = Count;
		}
 
 
	   // return values
		public String getName()
		{	
		return (name);
		}
		public float getPrice()
		{	
		return (price);
		}
		public int getItemno()
		{	
		return (itemno);
		}
		public int getNstock()
		{	
		return (nstock);
		}
		public int compareTo(Object in)
	   {
	   return ((Comparable)name.toLowerCase()).compareTo((Comparable)((Compactdisk)in).getName().toLowerCase());
	   }
 
		// returns indivudual inventory value for a disk
	   public float getValue()
	   {
	   return (price * nstock);
	   }
 
 
 
 
 
}// end class

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.text.*;
import java.lang.*;
 
public class CdwArtist extends Compactdisk
{
 
 private String artist; // artist performing on cd
 private float restock; // restocking percentage
 private float total; // inventory stock after restock
 private float invtotal; // total inventory value of all cds
 
 DecimalFormat formatter = new DecimalFormat("$0.00");
 
 // Artist constructor
  public CdwArtist()
 {
 artist = "";
 restock = .05f;
 total = .00f;
 invtotal = .00f;
 }
 
 public CdwArtist(String in)
 {
 artist=in;
 }
 
 // get values
 public void setArtist(String in)
 {
 artist=in;
 }
 public void setRestock(float cdRestock)
 {
 restock = cdRestock;
 }
 public void setTotal(float cdtotal)
 {
 total = cdtotal;
 }
 public void setInvtotal(float cdinvtotal)
 {
 invtotal = cdinvtotal;
 }
 
 // return value
 public String getArtist()
 {
 return (artist);
 }
 
 // returns indivudual inventory value for a disk
 public float getTotal()
 {
 return(price * nstock)+((price * nstock)* restock);
 }	
 
 
 
	//new toString
	public String toString()
	{
	return "<html>Artist: " + artist +
	" CD Name: " + name + 
	"<br> Item Number: " + itemno + 
	" Price: " + formatter.format(getPrice()) + 
	"<br> In Stock: " + nstock + 
	" Stock Value: " + formatter.format(getValue())  + 
	"<br> Restocking Fee: $" + restock + 
	"<br> Total Inventory Value For Item: "  + formatter.format(getTotal())+ "<hr></html>";
	}
} //End Class

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""

if (--currCD<0) currCD = listModel.size()-1;

newCD.setItemno(Integer.parseInt(itemField.getText()));

newCD.setText(Integer.parseInt(getItemno()));

itemField.setText( newCD.getItemno());