JTable: Custom Table Model (pI)

This is a follow-up to thread http://forum.java.sun.com/thread.jspa?threadID=725162 and thread http://forum.java.sun.com/thread.jspa?threadID=725158.
As I'm hoping to have a table of 5 columns, where the 4th and 5th columns are for integer and float data types respectively, I am creating a custom table model under the assumption that I will not know beforehand the number of rows the table will contain.
Problems? Having not specified the cell contents of the table, since it will be pupulated by users unknown to me, I did not declare or initialize a variable similar to TableDemo's data variable of type Object (see the TableDemo tutorial http://java.sun.com/docs/books/tutorial/uiswing/components/example-swing/TableDemo.java). As such, I am unable to specify the return parameters for the getRowCount() and getValueAt(~, ~) methods.
To overcome this, I sought to replicate the example shown in TableDemo by doing the following:
Object[][] cell = {"", "", "", new Integer(0), new Float(0.00f)};
public int getRowCount()
  returncell.length;
public Object getValueAt(int row, int column)
  return cell[row][column];
//...I got the following errors:
pathname\CustomTableModel.java:line #: incompatible types
found: java.lang.String
required: java.lang.Object[]
and the errors continue...
So I tried
Object[] cell = {"", "", "", new Integer(0), new Float(0.00f)};
// ...However, I got this error:
C:\...\CustomTableModel.java:line #:array required, but java.lang.String found
return cell[row][column];
.......................... ^
I just want to set the return parameters for getRowCount() and getValueAt(~,~) in the custom table model I'm creating. How do I do this?
Cheers!
PS Thanks for reading this far...

I decided to use the DefaultTableModel, after all. I was using it before, but at the time, i didn't know that certain things I wanted to accomplish, it could too.
Anyways, here's what I have been doing: http://forum.java.sun.com/thread.jspa?threadID=725861
Thanks nonetheless for your help. And by the way, my client is adamant that I use a LinkedList, rather than a Vector for this project. But nevertheless, thanks.

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    As was explained in pI, I'm creating a custom table model to overcome a few pitfalls I came across using the DefaultTableModel class, such as aligning cells, and getting certain columns to return only numeric type data. However, I've come upon a few roadblocks myself.
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    Thanks!
    I just got this response. Anyways, I found another solution that was, interestingly, from one of your threads written in 2005.
    This is what I did:
    // Letting the JTable know what each column stores and should return by
       // overloading the getColumnClass() method
       public Class getColumnClass(int column)
            if(recordsTable.getColumnName(column) == "Ranking")
              return Integer.class;
         /* Why do I keep ketting an IllegalArgumentException here? *
           * It keeps saying it cannot format given object as a Number */            
            else if(recordsTable.getColumnName(column) == "Price (�) ")
              return Float.class;
         else
           return getValueAt(0, column).getClass();         
       }However, another problem has arisen.
    The if method for the int column (Ranking column) works okay, and is even right-aligned. The else if arguments for the Price (�) column however is returning an IllegalArgumentException. This I just cannot figure out.
    Here's the code:package Practice;
      import java.awt.BorderLayout;
      import java.awt.Frame;
      import java.awt.Menu;
      import java.awt.MenuBar;
      import java.awt.MenuItem;
      import java.awt.MenuShortcut;
      import java.awt.event.ActionEvent;
      import java.awt.event.ActionListener;
      import java.awt.event.KeyEvent; // for MenuItem shortcuts
      import java.awt.event.WindowAdapter;
      import java.awt.event.WindowEvent;
      import java.awt.event.WindowListener;
      import javax.swing.JOptionPane;
      import javax.swing.JScrollPane; // JTable added to it, aiding flexibility
      import javax.swing.JTable; // The personally preferred GUI for this purpose
            // Provides a basic implementation of TableModel
      import javax.swing.table.DefaultTableModel;
              // This class uses Vector to store the rows and columns of data, though
              // programmer will be using LinkedLists
      import java.util.LinkedList;
      // User-defined classes
      import Practice.MusicDatabase;
      public class MusicBank extends Frame implements ActionListener
         MusicDatabase mDBase;
         Frame frame;
         String title = "",      // Frame's title
                file = "";           // pathname of the file to be opened
          // Declaring Menu and MenuItem variables
         Menu recordM; // ...
         // recordM
         MenuItem newRecordR_MI, deleteRecordR_MI;
         // Other irrelevant menus and sub items
        DefaultTableModel recordDetails;
        JTable recordsTable;
        LinkedList musicList;
        public MusicBank()
            musicList = new LinkedList();
            frame = new Frame(title);
            frame.setMenuBar(menuSystem());
            // Should user seek to close window externally
            frame.addWindowListener(new WindowAdapter()
                 public void windowClosing(WindowEvent we)
                     frame.dispose();
                     System.exit(0);
         recordDetails = new DefaultTableModel();
         // Creating the relevant columns
         recordDetails.addColumn("Title");
         recordDetails.addColumn("Identity");
         recordDetails.addColumn("Music Company");
         recordDetails.addColumn("Ranking");
         recordDetails.addColumn("Price (�) ");
         // Ensuring the table has at least one visible record (empty)
         recordDetails.addRow(populateRow("", "", "", 0, 0.00f));
         // Creating the table to display the data files (music record details)
         recordsTable = new JTable(recordDetails)
             // Letting the JTable know what each column stores and should return by
             // overloading the getColumnClass() method
            public Class getColumnClass(int column)
               if(recordsTable.getColumnName(column) == "Ranking")
                   return Integer.class;
                /* Why do I keep ketting an IllegalArgumentException here? *
                 * It keeps saying it cannot format given object as a Number */            
                else if(recordsTable.getColumnName(column) == "Price (�) ")
                    return Float.class;
                else
                    return getValueAt(0, column).getClass();         
      // Creating the menus
      public MenuBar menuSystem()
          MenuBar bar = new MenuBar();
          // Record menu and related items
          recordM = new Menu("Record");
          recordM.setShortcut(new MenuShortcut(KeyEvent.VK_R, false));        
          newRecordR_MI = new MenuItem("New record");
          newRecordR_MI.setShortcut(new MenuShortcut(KeyEvent.VK_N, false));
          deleteRecordR_MI = new MenuItem("Delete record");
          deleteRecordR_MI.setShortcut(new MenuShortcut(KeyEvent.VK_D, false));
           recordM.add(newRecordR_MI);
           recordM.addSeparator();
           recordM.add(deleteRecordR_MI);
            // Enabling menus with functionality
           newRecordR_MI.addActionListener(this);
           deleteRecordR_MI.addActionListener(this);
           // Adding menus and items to menu bar
           bar.add(recordM);
           return bar;        
      public void actionPerformed(ActionEvent ae)
          if(ae.getSource() == newRecordR_MI)
             newRecord();
          else if(ae.getSource() == deleteRecordR_MI)
             deleteRecord();       
      // Object that will be used, in conjunction with MusicDatabase's, to 
      // populate the JTable
      // A record in a JTable is equivalent to an element in a LinkedList
      public Object[] populateRow(String title, String name, String comp, int rank, float price)
          // First, update the LinkedList
          mDBase = new MusicDatabase(title, name, comp, rank, price);
          musicList.add(mDBase);
           // Then, update the table
           // As the parameters of Object tableDetails can only take a String or
           // object, rank and price will have to be cast as a String and later
           // parsed to their original form before use.
           String rankPT = ""+rank, pricePT = ""+price;        
           Object rowDetails[] = {title, name, comp, rankPT, pricePT};
           return rowDetails;
      public static void main(String args[])
          MusicBank app = new MusicBank();
           // Using the platform's L&F (if Win32,  Windows L&F; Mac OS, Mac OS L&F,
           // Sun, CDE/Motif L&F)
           // For more on this, refer to the WinHelp Java tutorial by F. Allimont
           try
               UIManager.getSystemLookAndFeelClassName();
           catch(Exception e)
               JOptionPane.showMessageDialog(app,
                    "Failed to create the Windows Look and Feel for this program",
                    "Look and Feel (L&F) error",
                    JOptionPane.ERROR_MESSAGE);
           app.frame.setSize(500, 500);
           app.frame.setVisible(true);
            // Placing frame in the centre of the screen on-loading
           app.frame.setLocationRelativeTo(null);
      // action methods per menu items
      // Also, why do I keep getting an ArrayIndexOutOfBoundsException
      // here? I do know what this exception is, and how it works, but just cannot
      // understand what is causing it
      public void newRecord()
          // Before adding a new record, check if previous record has complete
          // entries. If not, either display a message (JOptionPane) or disallow
          // request (simply do nothing)        
          // Proceed based on assesment
          if(queryState() == true)
              // Inform user that all entries need to be filled in before a new
              // record can be created
              JOptionPane.showMessageDialog(this, // current frame
                       "There are incomplete cells in the table."+
                       "\nPlease fill these in before proceeding",       // Message to user
                       "Incomplete entries",                                // Title
                       JOptionPane.ERROR_MESSAGE);                           // Relevant icon
          else
               // To ensure that both the linked list & the table are simultaneously
               // updated, JOptionPane's input dialogs are used to temporarily store
               // the data which is then inputted into both (linked list and JTable)
              String titleN, identityN, companyN; int rankN; float priceN;
              titleN = JOptionPane.showInputDialog(this, "Enter song title");
              identityN = JOptionPane.showInputDialog(this,                                      "Enter name of singer/band");
             companyN = JOptionPane.showInputDialog(this,                                 "Enter signed/unsigned company");
             rankN = Integer.parseInt( JOptionPane.showInputDialog(this,
                             "Enter rank (a number)") );
            System.out.println("\n JTable rows = "+recordDetails.getRowCount());
             // Ensuring that the chosen rank is not already entered
             /* Problem lies here */
             for(int row = 1; row <= recordDetails.getRowCount(); ++row)
                 if((recordDetails.getValueAt(row, 4)).equals(""+rankN))
                     rankN = Integer.parseInt( JOptionPane.showInputDialog(this,
                             "That number's already chosen.\nPlease enter a rank ") );
             priceN = Float.parseFloat( JOptionPane.showInputDialog(this,                                 "Finally, enter price �") );
             mDBase = new MusicDatabase(titleN, identityN, companyN, rankN, priceN);
             musicList.add(mDBase);
             recordDetails.addRow(populateRow(titleN, identityN, companyN, rankN,
         priceN));
             System.out.println("JTable rows after creation = "+
                   recordDetails.getRowCount());
         // Enabling the delete record menu item (as necessary)
         if((recordsTable.getRowCount()) > 0)
              deleteRecordR_MI.setEnabled(true);
      } // newRecord()
      public void deleteRecord()
         int selectedRow = recordsTable.getSelectedRow();
         recordDetails.removeRow(selectedRow);
          // Removing the element from the LinkedList's corresponding index
          musicList.remove(selectedRow);
          System.out.println("Existing rows = "+recordsTable.getRowCount());
           // If there are no more rows, disallow user from trying to delete rows
           if(selectedRow <= 0)
              deleteRecordR_MI.setEnabled(false);
      } // deleteRecord()
      // Method to query if all cells have changed their states (empty or not)
      public boolean queryState()
          // Obtaining number of rows
          int rows = recordDetails.getRowCount();
          int columns = recordDetails.getColumnCount();
          boolean isEmpty = false; // cell
          System.out.println("Rows = "+rows);
          System.out.println("Columns = "+columns);
          try{
              // Assessing all cells for complete entries
              // This approach is flexible, rather than hardcoding the rows available,
              // making it more reusable (assuming it will always be 5 columns)
              for (int rowIndex = 0; rowIndex<=rows; ++rowIndex)
                  if((recordDetails.getValueAt(rowIndex, 1)).equals(""))
                 isEmpty = true;
                  else if((recordDetails.getValueAt(rowIndex, 2)).equals(""))
               isEmpty = true;
                  else if((recordDetails.getValueAt(rowIndex, 3)).equals(""))
               isEmpty = true;                
                  else if((recordDetails.getValueAt(rowIndex, 4)).equals("0"))
               isEmpty = true;
                  else if((recordDetails.getValueAt(rowIndex, 5)).equals("0.00"))
               isEmpty = true;
          catch(Exception e)
             System.out.println(e.getMessage());
          return isEmpty;
      Now here is the code for the MusicDatabase class
    package Practice;
    class MusicDatabase
        private String songTitle, identity, musicCompany;
        private int rank;
        private float priceF;
        // Defining the constructor
        public MusicDatabase(String title, String name, String company,                                int rankingInt, float price)
           songTitle = title;
           identity = name;
           musicCompany = company;
           rank = rankingInt;
           priceF = price;
        } // constructor
       // Other methods
    } // class MusicDatabaseSorry, but am not sure if these codes are executable, as where I am (a general library), JVM is not on the machine I am using. (Remember, i don't have ready acess to the Internet, so I could not use my machine, nor the facilities that had the JVM - unavailable to me at the time).
    Thanks!
    Reformer...
    PS I do hope the code pasted was not too much. Kind regards....

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