Getting my data back from my JList

[no1zson]

Looks like I only made it a day and a half without a new question. I am not sure if that is good or bad.
I have everything just about the way I want it. I am now putting new buttons in to my GUI to manipulate everything put in my JList.
I added all the buttons to the GUI, put the architecture in so that I can just go in, one by one and edit them for functionality.
ADD works fine.
PREV is giving me an issue, and I am not even sure what it is.
I just want it to pull the last cd up so that I can look at it. Populate the given fields for possible modification should I decide to change or update anything.
What I have coded compiles, but after entering several cds, if I hit PREV I get:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:468)
at java.lang.Integer.parseInt(Integer.java:497)
at Inventory2.btnPrevActionPerformed(Inventory2.java:280)
at Inventory2.access$100(Inventory2.java:10)
at Inventory2$2.actionPerformed(Inventory2.java:155)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:5517)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3135)
at java.awt.Component.processEvent(Component.java:5282)
at java.awt.Container.processEvent(Container.java:1966)
at java.awt.Component.dispatchEventImpl(Component.java:3984)
at java.awt.Container.dispatchEventImpl(Container.java:2024)
at java.awt.Component.dispatchEvent(Component.java:3819)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
at java.awt.Container.dispatchEventImpl(Container.java:2010)
at java.awt.Window.dispatchEventImpl(Window.java:1791)
at java.awt.Component.dispatchEvent(Component.java:3819)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
This seems to indicate an issue with Integer vs Text or something like that with those lines. I do not understand that. Why would those lines be compatible in my ADD but not with the PREV.
I do not even know what problem I am trying to solve now.
Here is the complete 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 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

[peter_budo]

Can you please provide remining classes for this application. So far I do no see any problems here so copaling whole thing would be better

[PoovenM]

Hey, was just wondering... when you decrement currCD , how do you ensure that it isn't a negative number? Perhaps it is handled internally... but if it isn’t then wouldn’t that be an issue? Yeah was just wondering...

[no1zson]

Peter, here is my first 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

And the class that extends it

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

That is a good question Pooven. One I had not even considered until you asked it. I want to go back one record at a time, when I hit the very first record I would like to just loop around to the last record and start the process over again. Any suggestions?

[Ezzaral]

One I had not even considered until you asked it. I want to go back one record at a time, when I hit the very first record I would like to just loop around to the last record and start the process over again. Any suggestions?

Well, think about your index in relation to the list. If the decrement puts it past 0 you know what you want the next value to be and listModel has a size() function to help you out.

[Ezzaral]

Your parsing problem is clear from the exception message:

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

[/B]It's trying to parse an int from an empty string. If you look at the code in your previous handler, you have it backward. You want to set the text to the value from the object - not the other way around.

[no1zson]

Well, think about your index in relation to the list. If the decrement puts it past 0 you know what you want the next value to be and listModel has a size() function to help you out.

As I do not know how many elements can be in my JList at any given moment, would something like
For CurrCD < 0 listModel.Last();
bet a better option?

Either way, I am not sure of the syntax for the actual command.
What is the "return" or "get" command, I guess.

    // Grab Previous cd 
            CdwArtist newCD = (CdwArtist) listModel.get( currCD-- );
            For currCD < 0 listModel.size(99);
            newCD.setArtist(artistField.getText());
            newCD.setName(cdNameField.getText());

just does not look right to me.

Of course it is all mute if I cannot find the problem with the PREV button anyways, cuz it does not work now to begin with! ;)

[Ezzaral]

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

and then listModel.get(currCD); would work just fine.

[no1zson]

Your parsing problem is clear from the exception message:

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

[/B]It's trying to parse an int from an empty string. If you look at the code in your previous handler, you have it backward. You want to set the text to the value from the object - not the other way around.

If I understand you, in the ADD I am setting the object to the value of the text field (so that I can do calculations and what not), but now that I am taking that information back from the list, I need to set the text back to the value of the object?

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

is obviously the way to do number 1.
Will you show me an example of how to put it back?

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

Is what my limited experience tells me, but of course that is wrong.

[Ezzaral]

You simply call setText() on the textfield with the value from the cd object.

itemField.setText( newCD.getItemno());

[no1zson]

You simply call setText() on the textfield with the value from the cd object.

itemField.setText( newCD.getItemno());

makes perfect sense.
when I do it though

artistField.setText(newCD.getArtist());
			cdNameField.setText(newCD.getName());	
			itemField.setText(newCD.getItemno());
			nstockField.setText(newCD.getNstock());
			priceField.setText(newCD.getPrice())

the old familiar
Inventory2.java:282: setText(java.lang.String) in javax.swing.text.JTextComponent cannot be applied to (int)

Shows up for all three. Possibly something to do with it being a FormattedTextField????

[Ezzaral]

My bad, you'll need to use String.valueOf( newCD.getItemno() ) in the setText method for the numeric entries or a DecimalFormat formatter.

[no1zson]

My bad, you'll need to use String.valueOf( newCD.getItemno() ) in the setText method for the numeric entries or a DecimalFormat formatter.

Or one of each as the case calls for here. That is great. Thanks for the help.

Can you explain the way the list model size works for me?

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

I understand if the currCD counter is less than zero, then currCD impliments listModel.size()-1;
What does the -1 refer to? What does that mean?

Right now, it works, "kind of". If I put in 3 cds, and then hit PREV it goes from the 3rd to the 2nd, from the 2nd to the first, and then from the 1st back to the 3rd .... then it just bounces back and forth from the 3rd to the 1st ... it never goes to the second again.
I need to understand what it is doing, because I have a NEXT button to impliment which does exactly the opposite of the PREV, and then a FIRST and LAST button which go to the first and last records respectively and know I will need to use this command again.

[Ezzaral]

You don't want to get currCD-- from listModel, just currCD. You have already decremented it in the statement that handles the bounds rollover.

size()-1 is the index of the last item in the model, i.e. 10 items indexed from 0-9.

[peter_budo]

This whole function is wrong

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

Why do you try to pull info from text field if your text field is EMPTY ! ! ! You cleared out after reading data with add method

artistField.setText(null);
cdNameField.setText(null);	
itemField.setText(null);
nstockField.setText(null);
priceField.setText(null);

Read data from JList

[no1zson]

oooooooooo. I see.
Then, when I start going the other way, ie the NEXT button, ... hmmm,
I would think it would have to stay -1, as that still means end of the list, but how do I incement up? To what end? I would not know, would I?

if (++currCD>???) currCD = listModel.size()-1;
			CdwArtist newCD = (CdwArtist) listModel.get( currCD );

Ok, now you have got me perplexed. This affects also my First and Last records buttons as well.
I will not have to do an IF statement for those two, as I am just going to the first or last record, and the first record I know, so that statement should be easy

currCD = listModel.get()0;

I think,
but for LAST, I do not know what last will be ... any help with this?

[peter_budo]

>Then, when I start going the other way, ie the NEXT button, ... hmmm,
What you have to do is just check if the NEXT is smaller then size of your list. When the moving position become equal to list size I would just simple disable button and that apply for oposite direction move, if moving position equals to zero disable PREVIOUS button.

>This affects also my First and Last records buttons as well.
>but for LAST, I do not know what last will be ... any help with this?
Simple, calling FIRST you call first position in the list, which is actualy zero position. For LAST there is method which actualy return last check API properly

with first I think you been trying to say

currCD = listModel.get(0);

and last will be like thhis

currCD = listModel.lastElement();

don't forget deal with exception

[Ezzaral]

>with first I think you been trying to say

currCD = listModel.get(0);

and last will be like thhis

currCD = listModel.lastElement();

don't forget deal with exception

His usage there misled you a bit. Actually, the currCD variable is just an int index for the current cd, so the get(0) and lastElement() won't apply since they return the objects in those positions.

This is a simple matter of keeping track of an index. listModel.size()-1 is the index of the last item. From there, implementing your next() and last() code should be trivial to figure out.

[no1zson]

What exception? Exception to what? I do not know what that means.

I am still trying to wrap my brain around my NEXT button will go to that lastElement, and then loop back to the first again.

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

does not work. I am not sure how to tell currCD which element number is lastElement. Greater than what is my question?
I am also not sure listModel.size()+1; is correct either.

if (++currCD > listModel.lastElement()) currCD = listModel.size()+1;

Keeps coming from my fingers, but I know currCD and lastElement cannot be compared like that.

[Ezzaral]

Keeps coming from my fingers, but I know currCD and lastElement cannot be compared like that.

Which is why I keep pointing out listModel.size(). That is the current number of items in your list. That number -1 is the index of the last item. If your pointer equals the number of items, you have incremented too far and need to wrap back to the index of the first item.

[no1zson]

Which is why I keep pointing out listModel.size(). That is the current number of items in your list. That number -1 is the index of the last item. If your pointer equals the number of items, you have incremented too far and need to wrap back to the index of the first item.

I understand. The mystery to me is the index of the first item.
-1 is last item, but I do not know what to bring it around to once that is reached. T have searched up and down on listmodel but cannot find anything listing those. As a guess I used +1, it did not error on compile, but blows up when running.

if (++currCD > listModel.size()-1) currCD = listModel.size()1;

If I understand what I think I understand, this should work once I get the index of the first element.

[no1zson]

Or I could just do this.
if (++currCD >= listModel.size()) currCD= 0;
and not worry about it at all. Is this ugly programming by pro standards?

[Ezzaral]

Or I could just do this.
if (++currCD >= listModel.size()) currCD= 0;
and not worry about it at all. Is this ugly programming by pro standards?

That is exactly what I was trying to get you to figure out. You don't need any method calls to know that the first index is zero.

[no1zson]

Maybe you should use a bigger hammer next time! Thanks to both of you for helping me out yet AGAIN!
Promise I will get better eventaully.

I actually read up on the listModel API today without anyone having to yell at me.

[peter_budo]

There is quite nice book, Swing A Beginner's Guide by Herbert Schildt, I found it handy. I know it says beginner's but it is still good book in my opinion