I have spent the weekend reading about GUI and how Java uses it, and all I got was confused. :o) I decided the best way to learn it was just to get in to it and start coding, so that is what I did. Went better than I thought it would.
I feel I have a pretty good grip on it (at least for 1 day of practice) but what I do not seem to be able to figure out is how to alter my current cd inventory application to start using the GUI instead of my old DOS prompts. I want to use the same logic, same rules, and all that, except now I want the information to be entered from, and displayed in a GUI interface.
Do I have to write a whole new class and discard the Inventory one I use currently, or is there a way to apply the tried and tested rules I currently have and just mesh in GUI methods and constructors to take the place of what is there?
Any help would be welcome.
Here is my current GUI that I have been working on. It is simple, I just wanted to get the first two fields up to play with them.
First:

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class CdTextFrame extends JFrame
{
	public JTextField cdField1; // JLabel for CdwArtist class
	public JTextField cdField2;
	public JTextField cdField3;
	public JTextField cdField4;
	
	//CdFrame contructor adds Text Fields to JFrame
	public CdTextFrame()
	{
		super("CD Inventory");
		setLayout(new FlowLayout());  // set frame layout
		
		// 1st Field 
		cdField1 = new JTextField("CD Name");
		cdField1.setEditable(false); 
		add(cdField1);
		// 2nd Field
		cdField2 = new JTextField(10);
		cdField2.setToolTipText("Enter CD Name Here");
		add (cdField2);
		// 3rd Field 
		cdField3 = new JTextField("Artist");
		cdField3.setEditable(false); 
		add(cdField3);
		// 4th Field
		cdField4 = new JTextField(10);
		cdField4.setToolTipText("Enter Performing Artist Here");
		add (cdField4);
		
		// register event handlers
		CdFieldHandler handler = new CdFieldHandler();
		cdField2.addActionListener(handler);
		cdField4.addActionListener(handler);
		
		} // end constructor CdFrame
		
		// private inner class for event handling
		private class CdFieldHandler implements ActionListener
		{
			// process text field events method
			public void actionPerformed(ActionEvent event)
			{
			String string = "";   //declare string to display 
			
			// user pressed Enter in JTextField cdField2
			if (event.getSource()==cdField2)
				string = String.format("textField2: %s",
				event.getActionCommand());
				
			// user pressed Enter in JTextField cdField4
			if (event.getSource()==cdField4)
				string = String.format("textField4: %s",
				event.getActionCommand());
			
			// display JTextField content
			JOptionPane.showMessageDialog(null, string);
			} // end process text fields method
		} // end event handling class
} // end clss CdFrame

Does not really do anything yet, I put a listener in there just to try it. Right now it pops open a window with whatever you enter in the field, I think there is probably where I would have it write to my array, or is it? This is where I get in over my head. I do not know what to do with any of it yet.
Next is my tester class, again, it does nothing of real substance, just something for me to test and play with. I am wondering if this is where I will have to lay down new code to replace the rules in my Inventory class that I have used up until now.

import javax.swing.JFrame;

public class Cdguitext
{
	public static void main(String args[])
	{
	CdTextFrame cdTextFrame = new CdTextFrame(); // create cdframe
	cdTextFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	cdTextFrame.setSize(375,180);
	cdTextFrame.setVisible(true);
	} // end main
} // end class

Here is that class Inventory class. There are two classes (Compactdisk and CdwArtist) that this class uses for its parameters, if anyone needs to see them just let me know. They also are pretty basic get and set classes.

import java.util.*;

public class Inventory 
{// begin class Inventory

 public static int maxlength = 0;
  public static CdwArtist[] sort(CdwArtist[] cds)
   { 
	Arrays.sort(cds, 0, maxlength); 
	return cds;
	}
	
 public static String toString(CdwArtist[] cds)
  { 
  	String toSend = "\n\n"; 
	
	for(int i = 0; i < maxlength; i ++)
	toSend = toSend + cds[i].getName() + "\n";
	return toSend;
  } 
  
  public static void main(String[] args)
  {//begin method main
  
   // create cd Array 
	CdwArtist[] cds = new CdwArtist[100];
	
 
	float totalValue = 0; 
	
	Scanner input = new Scanner(System.in); // create scanner 
	
	// begin display method 
	System.out.print("Enter up to 99 CD Names or STOP to Exit: "); 
	String nameInput = input.nextLine(); //read cd name 
	
	
	 for(int i = 0; i < cds.length && !nameInput.equalsIgnoreCase("STOP"); i++)
	 {// begin main While
	  cds[i] = new CdwArtist();
	  cds[i].setName(nameInput);
	  
	  System.out.print("Enter CD Artist Name: "); // prompt for artist name
	  CdwArtist artist = new CdwArtist(input.nextLine()); 
	  	  	  
	  System.out.print("Enter Price of this CD: "); // prompt for price
	  cds[i].setPrice(input.nextFloat()); // price input from user. 
	  while (cds[i].getPrice()<= 0) 
	 	{// begin while 
	   	System.out.print("Price Must Be Greater Than Zero. Enter Price: ");
			cds[i].setPrice(input.nextFloat()); // cd price loop from user.
	  	} // End while 
	  
	  System.out.print("Enter CD Item Number: "); // prompt for cd item number
	  cds[i].setItemno(input.nextInt()); // cds item number input from user 
	  
	  System.out.print("Enter Number of these CDs in Stock: "); // prompt for cd stock 
	  cds[i].setNstock(input.nextInt()); // cds in stock input from user
	  
	  System.out.print("\n\nCD "+cds[i].getName()+", Item Number "+cds[i].getItemno()+","); // display name 
	  System.out.printf(" is worth %c%.2f.",'$', + cds[i].getPrice());//
	  System.out.print("\nWe have "+ cds[i].getNstock()+" copies in stock,");
	  System.out.printf(" making our inventory for this cd worth %c%.2f.\n", '$', + cds[i].getValue()); //inventory value 
	 
	  if(cds[i].getValue() != -1) totalValue = totalValue + cds[i].getValue();
	  System.out.printf("Combined Inventory for all CDs is Worth %c%.2f.\n\n\n", '$', + totalValue);
	  
	  System.out.print("Enter up to 99 CD Names or STOP to Exit: "); 
	  input=new Scanner(System.in); // internal loop prompt 
	  nameInput = input.nextLine(); //name input from user 
	  
	  maxlength ++; 
	  } // End main While
	  
	   //System.out.println(toString(cds));
		System.out.println(toString(sort(cds))); 
		System.out.print("Ending Program."); 

   }// end method main 
} // end class Payroll

I really hate to think all that coding goes to waste if I choose to use a GUI interface instead, I was hoping there was a way to put my GUI methods in this existing class, but if not ... then oh well, all part of the learning process I guess.

What I am trying to wrap my brain around, is how the GUI is going to talk to the array, and vice versa.
I had it in my mind (before I started) that when I began defining the fields of the GUI; field2, field4 and so on, that I would somehow be able to map the data that I entered into these new fields back to that array.
I am not sure I can do it that way anylonger, but I already have an array defined, working, and ready to be used, certainly I can create a GUI that uses it as it is, cant I?
Am I making sense?

You have two options (well, a lot more than 2 actually, but here are two):
Move the code that manages your array into the CdTextFrame class.
Give the Inventory class methods that let you add, remove, and view the CDs and call those methods from your CdTextFrame class.

Instead of a loop using Scanner, you will need a button to Add CD. You will want a JList to display the names of the current CDs in the array. You could also add buttons to Edit or Remove a CD from the Inventory. The listeners for these buttons can act upon the array itself if you have it in the CdTextFrame class, or call methods on the Inventory if you wish to put them there.

OK, I wanted to learn JList weeks ago, but did not have what I considered a good opportunity. I also will need to learn buttons, so I am going with option 2 here.
I have scrapped my CdTextFrame class completely and tried to start a JList the way my book has it, but I am missing something.

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GuicdInventory extends JFrame
{
	Inventory guiInventory = new Inventory();
	
	private Jlist cDJList;
	
	
	//contructor adds  Inventory to JFrame
	public GuicdInventory()
	{
		super("CD Inventory");
		setLayout(new FlowLayout());  // set frame layout
		
		[B]cDJList = new JList(Object[] guicdInventory);[/B]
		cDJList.setVisibleRowCount(99);		
		add(new JScrollPane(cDJList));
		
		} // end constructor
		
				
			public static void main(String args[])
			{
			GuicdInventory guiceInentory = new GuicdInventory;
			GuicdInventory.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			GuicdInventory.setSize(500,800);
			GuicdInventory.setVisible(true);
			} // end f 
			
} // end main

I want to learn this a step at a time so that I do not get in over my head, but I am getting .class expected, and ; expected on the bolded line above, pointing at "guiInvnetory".
If I am understanding you, I will want to create the JList in this new class, and a button in my old Inventory class to replace my scanner, and that will enable me to simply list my array inventory?

Well, I had noticed buttons before, so I think this is pretty close to right. How I replace the loop with one is a bit of a mystery at this point, but right now, even with all the new stuff here I am still getting that same message on the same line.

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GuicdInventory extends JFrame
{
	Inventory guiInventory = new Inventory();
	
	private Jlist cDJList;
	
	
	//contructor adds  Inventory to JFrame
	public GuicdInventory()
	{
		super("CD Inventory");
		setLayout(new FlowLayout());  // set frame layout
		
		// adds buttons
		addButton = new Button("Add");
		add (addButton);
		
		// create an object to listen to buttons
		ButtonListener myButtonListener = new ButtonListener(); 
		
		// tell buttons that myButtonListener should be notified
		addButton.addActionListener(myButtonListener); 
		setVisible(true); 
		
		cDJList = new JList(Object[] guicdInventory);
		cDJList.setVisibleRowCount(99);		
		add(new JScrollPane(cDJList));
		
		} // end constructor
		
				
			public static void main(String args[])
			{
			GuicdInventory guiceInentory = new GuicdInventory;
			GuicdInventory.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			GuicdInventory.setSize(500,800);
			GuicdInventory.setVisible(true);
			} // end  
			
} // end main

By starting on GUI programming, you are venturing a lot deeper into OO programming then you've ever been before. Java has some extremely flexible APIs for visual components but they come at a cost of complexity.

The no class found is because you have used a variable you haven't defined (you mispelled it). Also, this line:

GuicdInventory guiceInentory = new GuicdInventory;

will not compile - no parenthesis.

The button to add new will not go into another class. It has to remain in the JFrame class. You will need the action listener to perform whatever code is needed to add the new CD.

Comments
friendly and helpful, makes you learn.

Yeah, I am seeing that. I want to try and keep this as simple as possible. Too complicated and I am just going to frustrate myself.
I found the misspellings and the parenthesis in my last post, I think you were looking at code I posted before I found them. I did put the Button code in my JFrame extention also.
Editing the loop will be the next step, but first I have to get this list working and I am still getting the same error on the same line.

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GuicdInventory extends JFrame
{
	Inventory guicdInventory = new Inventory();
	
	private Jlist cDJList;
	
	
	//contructor adds  Inventory to JFrame
	public GuicdInventory()
	{
		super("CD Inventory");
		setLayout(new FlowLayout());  // set frame layout
		
		// adds buttons
		addButton = new Button("Add");
		add (addButton);
		
		// create an object to listen to buttons
		ButtonListener myButtonListener = new ButtonListener(); 
		
		 
		
		cDJList = new JList(Object[] guicdInventory);
		cDJList.setVisibleRowCount(99);		
		add(new JScrollPane(cDJList));
		
		} // end constructor
		
				
			public static void main(String args[])
			{
			GuicdInventory guicdInentory = new GuicdInventory;
			GuicdInventory.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			GuicdInventory.setSize(500,800);
			GuicdInventory.setVisible(true);
			// tell buttons that myButtonListener should be notified
			addButton.addActionListener(myButtonListener); 
			setVisible(true);
			} // end  
			
} // end main

I am going to go to lunch before I get too aggravated. Maybe it will look differently when I get back! :o)

I hate that site. I was trying to read up on arrays there this morning. Just made me more confused.
I know it is helpful to people that already understand what is going on, but for me, being the first time I have ever attempted any of this, it is vague examples I do not understand.
It is good for giving me an idea of what I should try, but when I have specific questions it just makes my head swim ... like now.

It is complaining because this line

cDJList = new JList(Object[] guicdInventory);

is not a valid parameter to the constructor - you don't need the Object[] part, just a variable that is an array of Object.

Keep in mind, if you pass in an object array, JList will use the value of toString() for that object in the list. You may have to override

public String toString()

in your CD class to have the name or other description appear in your list.

Also, if you haven't added any CDs to the array at the point you create the list, there won't be anything to display :)

I did have concerns about the toString, but again fall into unfamiliar territory with that function.
I do understand what you say about the list being empty, which goes back to an overall question about how the GUI pulls information, and from where.
I think I am way over my head here, I think I probably need to scrap the JLIST and just go back to the original plan and insert everything into a new gui class that uses my Compactdisk and Cdwartist classes.
Right now I am trying to build on a foundation I have not properly laid yet.
1st thing I need to do is get a QUI screen with some fields in it where I can enter information into my existing array.
Then I will worry about sorting, adding and all that other stuff.
Would you suggest I take everything from Inventory and just re-write it into my new class, so that I do not use Inventory anymore?

You could, if you feel that is easier for you to logically work with. JList has it's own container (the list model) that you can put CDs into. The part from your loop in inventory will largely be replaced by code in a button that creates a new CD, reads the info from your text fields and sets the properties on the CD, and then adds it to the list model.

That is a lot of my problem right there, at this point I am not even sure what I should do. This is my first attempt at GUI so I wanted to stay as basic as possible, and keep as much of my existing code as possible because I understand it as it is (for the most part.)
I have never used JList either, so between that and GUI both at once I am just getting confused as to what is changing by implimenting one, and what changes because of the other.
I am looking at the code I have attempted today, some for GUI frames, some for buttons, some for JList ... all of it new, and none of it clear.
I think I am going to delete everything I have tried up to this point, and just start over. :o(

Yes, GUI code can be a little complex to jump into. You just have to start simple and keep at it. Perhaps this demo will help. It's just a tiny form I knocked up that let's you add a CD with artist and title to a JList.

import javax.swing.DefaultListModel;

public class ListDemo extends javax.swing.JFrame {
    
    private javax.swing.JButton btnAdd;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JLabel lblArtist;
    private javax.swing.JLabel lblTitle;
    private javax.swing.JList lstInventory;
    private javax.swing.JTextField txtArtist;
    private javax.swing.JTextField txtTitle;
    
    private DefaultListModel listModel;
    
    
    public ListDemo() {
        initComponents();
    }
    
    private void initComponents() {
        lblArtist = new javax.swing.JLabel();
        txtArtist = new javax.swing.JTextField();
        lblTitle = new javax.swing.JLabel();
        txtTitle = new javax.swing.JTextField();
        btnAdd = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        lstInventory = new javax.swing.JList();

        getContentPane().setLayout(new java.awt.FlowLayout());

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        
        lblArtist.setText("Artist");
        getContentPane().add(lblArtist);

        txtArtist.setMinimumSize(new java.awt.Dimension(75, 19));
        txtArtist.setPreferredSize(new java.awt.Dimension(75, 19));
        getContentPane().add(txtArtist);

        lblTitle.setText("Title");
        getContentPane().add(lblTitle);

        txtTitle.setMinimumSize(new java.awt.Dimension(75, 19));
        txtTitle.setPreferredSize(new java.awt.Dimension(75, 19));
        getContentPane().add(txtTitle);

        btnAdd.setText("Add");
        btnAdd.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnAddActionPerformed(evt);
            }
        });

        getContentPane().add(btnAdd);
        
        listModel = new DefaultListModel();
        lstInventory.setModel(listModel);        

        jScrollPane1.setViewportView(lstInventory);

        getContentPane().add(jScrollPane1);

        pack();
    }

    private void btnAddActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // Create cd and set title
        CD cd = new CD(txtArtist.getText());
        cd.setTitle(txtTitle.getText());
        
        // Add the cd to list
        listModel.addElement(cd);
        
        // Clear the text fields
        txtArtist.setText(null);
        txtTitle.setText(null);
    }                                      
    
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ListDemo().setVisible(true);
            }
        });
    }
    
    /** Small CD class to hold our data */
    class CD {
        private String artist;
        private String title;
        
        public CD(String artist){
            this.artist = artist;
        }
        
        public void setTitle(String title){
            this.title = title;
        }
        
        public String toString(){
            return artist + " - " + title;
        }
    }
    
    
}

I am going to see what I can do with that and get back with you tomorrow.
I appreciate your patience.

Just so you know I was not just sitting around waiting on code, here is what I had come up with over the afternoon ... looking at what you hve done I think I was at least headed in the right direction. I was rewriting my entire Inventory class from the ground up. I am not exactly sure where I was going with it, but I kept the idea stream flowing and this is where it took me. :o)

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

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 JLabel valueLabel; // value of that item label 
	private JLabel rstkLabel; // cost to restock label 
	private JLabel totalLabel; // total value of inventory 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 JFormattedTextField valueField; // value of that item display 
	private JFormattedTextField rstkField; // cost to restock display 
	private NumberFormat nstockFormat; // format field and parse numbers 
	private NumberFormat priceFormat; // format field and parse numbers 
	private NumberFormat valueFormat; // format field and parse numbers 
	private NumberFormat rstkFormat; // format field and parse numbers 
	private JButton firstBtn; // first button 
	private JButton prevBtn; // previous button 
	private JButton nextBtn; // next button 
	private JButton lastBtn; // last 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; // current product display to use for button action 
	private int i; // iterator 
	private double total = 0; // variable for total inventory 

	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:"); 
		valueLabel = new JLabel("Value of Item Inventory:"); 
		rstkLabel = new JLabel("Cost to Re-Stock Item:"); 
		totalLabel = new JLabel("Total Value of Inventory:$"+total); 
		
		// create button names 
		firstBtn = new JButton("First"); 
		prevBtn = new JButton("Previous"); 
		nextBtn = new JButton("Next"); 
		lastBtn = new JButton("Last"); 

		// create textFields and set uneditable 
		cdNameField = new JTextField(15); 
		cdNameField.setEditable(false); 

		artistField = new JTextField(15); 
		artistField.setEditable(false); 
		; 
		nstockField = new JFormattedTextField(nstockFormat); 
		nstockField.setEditable(false); 
		nstockField.setColumns(10); 
		
		priceField = new JFormattedTextField(priceFormat); 
		priceField.setEditable(false); 
		priceField.setColumns(10); 
		
		itemField = new JTextField(15); 
		itemField.setEditable(false); 
		
		valueField = new JFormattedTextField(valueFormat); 
		valueField.setEditable(false); 
		valueField.setColumns(10); 
		
		rstkField = new JFormattedTextField(rstkFormat); 
		rstkField.setEditable(false); 
		rstkField.setColumns(10);
		
		// add buttons to panel 
		JPanel buttons = new JPanel(); // set up panel 
		buttons.setLayout( new GridLayout(1, 4)); //set layout 
		// add buttons to buttons 
		buttons.add(firstBtn); 
		buttons.add(prevBtn); 
		buttons.add(nextBtn); 
		buttons.add(lastBtn);
		
		 
		// create cd Array 
		CdwArtist[] cds = new CdwArtist[100];
 
 		for(int i = 0; i < cds.length && !nameInput.equalsIgnoreCase("STOP"); i++)
		cds[i] = new CdwArtist();
	  	cds[i].setName(nameInput);
		//total += cdProduct[currCD].calcValue(); // calculate total inventory cost 
		
		// add values to textFields 
		cdNameField.setText(cds[i].getProdName()); 
		artistField.setValue(new Integer(cds[i].getArtist()));
		nstockField.setValue(new Integer(cds[i].getUnits())); 
		priceField.setValue("$"+new Double(cds[i].getPrice())); 
		itemField.setText(cds[i].getFeature()); 
		valueField.setValue("$"+new Double(cds[i].calcValue())); 
		rstkField.setValue("$"+new Double(cds[i].calcValueRstk()))

I did not understand it at first, but after sitting down and comparing it to what I was writing I could see what I was trying to do, and it cleared up in my head.
Then I started coding, and as I created everything I could see the logic behind what was being built, how the buttons, fields, and JList all work together.
I do have a few questions of course, if you have a moment, ;)
Here is everything, from your original work, to what I have added:

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 JLabel valueLabel; // value of that item label 
    private JLabel rstkLabel; // cost to restock label 
    private JLabel totalLabel; // total value of inventory 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 JFormattedTextField valueField; // value of that item display 
    private JFormattedTextField rstkField; // cost to restock display
    private JFormattedTextField totalField; // value of all inventory combine 
    private NumberFormat nstockFormat; // format field and parse numbers 
    private NumberFormat priceFormat; // format field and parse numbers 
    private NumberFormat valueFormat; // format field and parse numbers 
    private NumberFormat rstkFormat; // 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 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; // current product display to use for button action 
    private int i; // iterator 
    private double total = 0; // variable for total inventory 
    private JList Inventorylist; // JList to take place of old array
    private DefaultListModel listModel;
    private JScrollPane jScrollPanel;  

    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:"); 
        valueLabel = new JLabel("Value of Item Inventory:"); 
        rstkLabel = new JLabel("Cost to Re-Stock Item:"); 
        totalLabel = new JLabel("Total Value of Inventory:$"+total); 

        // JList
        jScrollPanel = new JScrollPane();
        Inventorylist = new JList(); 

        // buttons 
        btnAdd = new JButton(); 
        btnNext = new JButton(); 
        btnPrev = new JButton(); 
        btnDel = 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(75,19)); 
        artistField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(artistField); 

        // cd name
        cdNameLabel.setText("CD Name"); 
        getContentPane().add(cdNameLabel); 

        cdNameField.setMinimumSize(new Dimension(75,19)); 
        cdNameField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(cdNameField);

        // copies in stock
        nstockLabel.setText("Copies In Stock"); 
        getContentPane().add(nstockLabel); 

        nstockField.setMinimumSize(new Dimension(75,19)); 
        nstockField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(nstockField); 

        //price of cd
        priceLabel.setText("Price"); 
        getContentPane().add(priceLabel); 

        priceField.setMinimumSize(new Dimension(75,19)); 
        priceField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(priceField); 

        //item number of cd
        itemLabel.setText("Item Number"); 
        getContentPane().add(itemLabel); 

        itemField.setMinimumSize(new Dimension(75,19)); 
        itemField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(itemField);; 

        // value of individual cd in stock
        valueLabel.setText("Value"); 
        getContentPane().add(valueLabel); 

        valueField.setMinimumSize(new Dimension(75,19)); 
        valueField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(valueField); 

        // restocking fee
        rstkLabel.setText("Restock Fee"); 
        getContentPane().add(rstkLabel); 

        rstkField.setMinimumSize(new Dimension(75,19)); 
        rstkField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(rstkField);

        // total value of inventory
        totalLabel.setText("Total Inventory Value"); 
        getContentPane().add(totalLabel); 

        totalField.setMinimumSize(new Dimension(75,19)); 
        totalField.setPreferredSize(new Dimension(75,19));
        getContentPane().add(totalField);   

        // add buttons
        //ADD
        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)
            {
                btnAddActionPerformed(evt);
            }
        });
        getContentPane().add(btnPrev);

        // NEXT
        btnNext.setText("Next");        
        btnNext.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent evt)
            {
                btnAddActionPerformed(evt);
            }
        });
        getContentPane().add(btnNext);

        // 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
            CD cd = new CD(artistField.getText());
            cd.setcdName(cdNameField.getText());    
            cd.setitem(itemField.getText());
            cd.setnstock(nstockField.getText());
            cd.setprice(priceField.getText());
            cd.setvalue(valueField.getText());
            cd.settotal(totalField.getText());
            cd.setrstk(rstkField.getText());    

            // Add cd to list
            listModel.addElement(cd);

            // Clear the text fields after add
            artistField.setText(null);
            cdNameField.setText(null);  
            itemField.setText(null);
            nstockField.setText(null);
         priceField.setText(null);
            valueField.setText(null);
            rstkField.setText(null);
            totalField.setText(null);
        }// end ADD


        // run it
        public static void main(String args[])
        {
        java.awt.EventQueue.invokeLater(new Runnable()
            {
            public void run()
                {
                new Inventory2().setVisible(true);
                }
            });
        }

} // close class

That is the first class I have written where I understood what I was doing from start to finish. I do have a few details I need to pick your brain about.
first: CD cd = new CD(artistField.getText());
I know what this is doing, but I am getting the error cannot find symbol pointing at CD.
I even understand the error, I do not see where CD is defined anywhere, nor do I know where it would be put.
second: I also plan to go in an modify my previous Compactdisk and CdwArtist classes for use with this class. How does this class know to use those two?

Edited 3 Years Ago by pyTony: fixed formating

first: CD cd = new CD(artistField.getText());
I know what this is doing, but I am getting the error cannot find symbol pointing at CD.
I even understand the error, I do not see where CD is defined anywhere, nor do I know where it would be put.
second: I also plan to go in an modify my previous Compactdisk and CdwArtist classes for use with this class. How does this class know to use those two?

CD was the small inner class that I put in my listing to hold cd data. You will want to change that to your own CdwArtist class. You will need to override the toString method on that class so that it shows what you want in the list also. Look at the bottom of my code for the CD class definition to see how that is done.

I feel like a genious (about the CdwArtist class), I had just gotten that to work, and have my sets going to that class ...
here is what it looks like now

// Create cd to add
			CdwArtist cd = new CdwArtist(artistField.getText());
			cd.setName(cdNameField.getText());	
			cd.setItemno(itemField.getText());
			cd.setNstock(nstockField.getText());
			cd.setPrice(priceField.getText());
			cd.setValue(valueField.getText());
			cd.setTotal(totalField.getText());
			cd.setRestock(rstkField.getText());

It must be working because it sees that some of those fields (Itemno for example) is defined as INT in the other class.
It is erroring telling me that those parameters cannot be applied to java.lang.String
I "kind of" understand what it is saying, I have numbers in these fields, some of which I will be doing calculations as, but it is expecting a String. Right? Where would I alter that?
I am going to look at the toString right now and see if I can figure out what you are telling me there.
Thanks again for your help!

I believe I have the toString right.
The only thing I am having trouble with, logically, and code wise at the moment is how to solve the String/Int problem in Inventory2.

Do these fields not need to be int, double, or float in order to perform calculations on them?

It must be working because it sees that some of those fields (Itemno for example) is defined as INT in the other class.
It is erroring telling me that those parameters cannot be applied to java.lang.String
I "kind of" understand what it is saying, I have numbers in these fields, some of which I will be doing calculations as, but it is expecting a String. Right? Where would I alter that?

The numeric type wrapper objects, such as Integer, Float, Double, etc. have static methods for parsing strings to primary types. In the case of the int, you can use Integer.parseInt(itemField.getText()); to convert the string to an int value.

You will of course get an error if the input cannot be parsed into an int, which is something that would need to be guarded against in a production program, but for your purposes now you can just parse it - you don't need the additional complexity of validation just yet :)

Other parsing functions include Float.parseFloat(), Double.parseDouble(), and Long.parseLong() in case you need them.

Wow. I am not even going to pretend to understand that!
As always you were right though, and after some modifications to my other two classes I was ready to go. No compile errors ... excitement high ... BOOM!

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at Inventory2.initComponents(Inventory2.java:82)
	at Inventory2.<init>(Inventory2.java:47)
	at Inventory2$5.run(Inventory2.java:231)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

I guess now is as good a time as any to learn about NullPointerException ... if you are willing to part with the knowledge, but man I was ready to see this work.
DOS is great, but it is not real programming until I get a GUI in my face!

NullPointerException occurs when you attempt to call a method on an object that is null. You probably tried to call a method on an object you haven't yet initialized. The stack trace indicates this is occuring around line 82 (the line number is not always exact) in the initComponents() method.

Does it have to be in the Inventory2 class? Or can this indicate a problem in one of the other two?
I cannot see anything wrong in this class.

If I am reading the error correctly, which is anything but garanteed, it does not like Inventory2, or artist.
Since I could see nothing here, I played with artist in my CdwArtist class, but nothing changes.

The trace points to

at Inventory2.initComponents(Inventory2.java:82)

Make sure you don't have a ui component that you haven't initialized yet.

That is what I thought. I have gone through it and through it again.
8 fields. 1 jList. 4 buttons and a panel.
Am I just blind?

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 JLabel valueLabel; // value of that item label 
	private JLabel rstkLabel; // cost to restock label 
	private JLabel totalLabel; // total value of inventory 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 JFormattedTextField valueField; // value of that item display 
	private JFormattedTextField rstkField; // cost to restock display
	private JFormattedTextField totalField; // value of all inventory combine 
	private NumberFormat nstockFormat; // format field and parse numbers 
	private NumberFormat priceFormat; // format field and parse numbers 
	private NumberFormat valueFormat; // format field and parse numbers 
	private NumberFormat rstkFormat; // 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 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; // current product display to use for button action 
	private int i; // iterator 
	private double total = 0; // variable for total inventory 
	private JList Inventorylist; // JList to take place of old array
	private DefaultListModel listModel;
	private JScrollPane jScrollPanel;  

	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:"); 
		valueLabel = new JLabel("Value of Item Inventory:"); 
		rstkLabel = new JLabel("Cost to Re-Stock Item:"); 
		totalLabel = new JLabel("Total Value of Inventory:$"); 
		
		// JList
		jScrollPanel = new JScrollPane();
		Inventorylist = new JList(); 
		
		// buttons 
		btnAdd = new JButton(); 
		btnNext = new JButton(); 
		btnPrev = new JButton(); 
		btnDel = 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(75,19)); 
		artistField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(artistField); 
		
		// cd name
		cdNameLabel.setText("CD Name"); 
		getContentPane().add(cdNameLabel); 

		cdNameField.setMinimumSize(new Dimension(75,19)); 
		cdNameField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(cdNameField);
		
		// copies in stock
		nstockLabel.setText("Copies In Stock"); 
		getContentPane().add(nstockLabel); 

		nstockField.setMinimumSize(new Dimension(75,19)); 
		nstockField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(nstockField); 
		
		//price of cd
		priceLabel.setText("Price"); 
		getContentPane().add(priceLabel); 

		priceField.setMinimumSize(new Dimension(75,19)); 
		priceField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(priceField); 
		
		//item number of cd
		itemLabel.setText("Item Number"); 
		getContentPane().add(itemLabel); 

		itemField.setMinimumSize(new Dimension(75,19)); 
		itemField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(itemField);; 
		
		// value of individual cd in stock
		valueLabel.setText("Value"); 
		getContentPane().add(valueLabel); 

		valueField.setMinimumSize(new Dimension(75,19)); 
		valueField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(valueField); 
		
		// restocking fee
		rstkLabel.setText("Restock Fee"); 
		getContentPane().add(rstkLabel); 

		rstkField.setMinimumSize(new Dimension(75,19)); 
		rstkField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(rstkField);
		
		// total value of inventory
		totalLabel.setText("Total Inventory Value"); 
		getContentPane().add(totalLabel); 

		totalField.setMinimumSize(new Dimension(75,19)); 
		totalField.setPreferredSize(new Dimension(75,19));
		getContentPane().add(totalField);	
		
		// add buttons
		//ADD
		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)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnPrev);
		
		// NEXT
		btnNext.setText("Next");		btnNext.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent evt)
			{
				btnAddActionPerformed(evt);
			}
		});
		getContentPane().add(btnNext);
				
		// 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 cd = new CdwArtist(artistField.getText());
			cd.setName(cdNameField.getText());	
			cd.setItemno(Integer.parseInt(itemField.getText()));
			cd.setNstock(Integer.parseInt(nstockField.getText()));
			cd.setPrice(Float.parseFloat(priceField.getText()));
			cd.setValue(Float.parseFloat(valueField.getText()));
			cd.setTotal(Float.parseFloat(totalField.getText()));
			cd.setRestock(Float.parseFloat(rstkField.getText()));	
			
			// Add cd to list
			listModel.addElement(cd);
			
			// Clear the text fields after add
			artistField.setText(null);
			cdNameField.setText(null);	
			itemField.setText(null);
			nstockField.setText(null);
         priceField.setText(null);
			valueField.setText(null);
			rstkField.setText(null);
			totalField.setText(null);
		}// end ADD
		
		
		// run it
		public static void main(String args[])
		{
		java.awt.EventQueue.invokeLater(new Runnable()
			{
			public void run()
				{
				new Inventory2().setVisible(true);
				}
			});
		}
			
} // close class

I do not doubt it. I played with netbeans yesterday for awhile and it seemed easier than this, but the whole purpose is to familiarize myself with the guts of it.
I would like to understand what is happening in the background before I try to get fancy.

Take a look at the component on line 82 and I think you will see which component(s) are causing the problem.

Fields must also be initialized!!!
duh!!
Thank you so much. This has of course pointed out other errors that I need to work on. But you have helped me so much today.
I enjoy the interaction.

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