I don't understand why my JTable will not display data

[Geoff Jefferson]

I believe a good starting point will be to look at my table model.
As long as the list being passed to the constructor is ok,
shouldn't this work?

   

import javax.swing.table.AbstractTableModel;
import java.util.List;
import java.util.ArrayList;

@SuppressWarnings("serial")

class CarrierTableModel extends AbstractTableModel  {
  
  ReadItemFile readIF = null;  
  String[] columnNames = {"Model", "Description", "CLS",
                                     "SDT Cost"};
  protected List<ItemCarrier> list = new ArrayList<ItemCarrier>();

 CarrierTableModel() { } 
 
  CarrierTableModel(List<ItemCarrier> argList){
      list = argList;
  }
    
  @Override  public int getRowCount() {
    return list.size();
  }
  @Override   public int getColumnCount() {
    return columnNames.length;
  }
  @Override public String getColumnName(int col) {
    return columnNames[col];
  }
  @Override public Object getValueAt(int row, int col) {

  ItemCarrier item = (ItemCarrier)list.get(row);
           
      switch(col) {
         case 0: return item.one;
         case 1: return item.two;
         case 2: return item.three;
         case 3: return item.four;
         default: assert false; return null;
      }
  }
  public void loadList(List<ItemCarrier> listArg) {
      list = listArg;
  }
  public void updateTable() {
      fireTableDataChanged();
  }
  public void addItem(ItemCarrier item){
      list.add(item);
      fireTableDataChanged();
  }
  public ItemCarrier getItem(int a) {
      return list.get(a);    
  }
  public  List<ItemCarrier> getList(){
      return list;
  }   
  public void clearList() {
      list.clear();
      fireTableDataChanged();
  }
  public int getSize(int i) {
      return list.size();
  }

} // end class

[Paul Clapham]

It should work... assuming the model for your JTable is an instance of this class, and assuming that instance was created with a non-empty list. And probably assuming several other things which don't come to mind because you didn't show us that code.

How about creating a short but compilable example which demonstrates your problem? Let's see... a JTable, a CarrierTableModel, a List with one entry, put it all in a JFrame, should come in at under 50 lines of code.

[Geoff Jefferson]

Here is the UI.

  

import java.util.ArrayList;
import java.util.List;


public class HVACBuilderUI extends javax.swing.JFrame {
    
    protected List<ItemCarrier> list = new ArrayList<ItemCarrier>();
    ReadItemFile read = new ReadItemFile();
    
    CarrierTableModel myTable = new CarrierTableModel(list);    

    /** Creates new form HVACBuilderUI */
    public HVACBuilderUI() {
        list = read.readFile();  // gets the list
        initComponents();
    }

private void initComponents () {

// netBeans generated GUI code here

// The table declaration an initialization is like this

private javax.swing.JTable jTable;

jTable1 = new javax.swing.JTable(myTable);

jScrollPanel.setViewportView(jTable);

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
      ResidentialNew.createAndShowGUI();
}                                        

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
   ReadExcel read = new ReadExcel();
   read.getData();
}                                        

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         

// tested the list here and looks ok    
/*        
   ReadItemFile read = new ReadItemFile();
   List<ItemCarrier> list;
   list = read.readFile();
   Object obj = null;
   obj = list.get(1);
   ItemCarrier item;
   item = (ItemCarrier)obj;
   System.out.println("test     " + item.two);
*/
   
}                                        

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new HVACBuilderUI().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JButton jButton4;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JSeparator jSeparator3;
    private javax.swing.JSeparator jSeparator4;
    private javax.swing.JTable jTable1;
    // End of variables declaration

    
}









 

[Geoff Jefferson]

The list implementation seems to work okay. I tested via sending output ot standard out.
For some reason I can't get it in my head where to load the list from file ect.

Here is the file that retrieves the data from file.

 
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.ArrayList;
/*
 * Reads the item file that was created by ReadExcel
 * and returns List<ItemCarrier> to caller.
 */
import java.util.List;

public class ReadItemFile {
    
    ReadItemFile() { }

    protected final List<ItemCarrier> list   = new ArrayList<ItemCarrier>();

    private FileInputStream   fIn  = null;
    private ObjectInputStream  oIS = null; 

    public List<ItemCarrier> readFile() {  // List<ItemCarrier>
     System.out.println(" from try");
    
        try {       
      
          fIn = new FileInputStream
                   ("C:\\Jeff\\NetBeans Gui Building\\MyTableMain\\DataFiles");
             oIS = new ObjectInputStream(fIn);
             
             Object obj = null;
                // while loop will run until the IOExeption is thrown.
             while ((obj = oIS.readObject()) != null) {
                ItemCarrier item = (ItemCarrier) obj;
                list.add(item);
             }
        
      } 
            catch (ClassNotFoundException evt) {
              evt.printStackTrace();
            }
            catch(IOException evt) {
               evt.printStackTrace(); 
             }  
            
             catch (IllegalArgumentException evt) {
                evt.printStackTrace();
             }
             
             catch(SecurityException evt){
                evt.printStackTrace();
             }
             catch(NullPointerException evt){
                evt.printStackTrace();
             }
             finally {
               if (fIn != null){ 
                  try {
                    fIn.close();
                  }
                  catch (IOException evt){
                    evt.printStackTrace();
                  }     // end catch
               } // end if
             }   // end finally
           
        return list;
    }
    
}


   

[Paul Clapham]

I should have mentioned that your example should be self-contained. That example, if I were to try it, would fail to compile because it refers to some other class. And I'm guessing that even if I had that other class, it would fail to run because it requires reading from some file.

So your example is too complicated. Simplify it by removing all the buttons (they are irrelevant). Simplify it by removing the code which reads from a file and just use code which creates one object from hard-coded data and adds that to the list.

[Geoff Jefferson]

>> So your example is too complicated. Simplify it by removing all the buttons (they are irrelevant). Simplify it by removing the code which reads from a file and just use code which >> creates one object from hard-coded data and adds that to the list.

Okay, but It might take me a day or two. I do this while I work--well, in between work.

[Geoff Jefferson]

Reviesed UI, now I get one row of blank cells.

   

import java.util.ArrayList;
import java.util.List;

/*
 * HVACBuilderUI.java
 *
 * Created on June 7, 2009, 12:17 PM
 */

public class HVACBuilderUI extends javax.swing.JFrame {
    
    protected List<ItemCarrier> list = new ArrayList<ItemCarrier>();
    
    CarrierTableModel myTable = new CarrierTableModel(list);    

    /** Creates new form HVACBuilderUI */
    public HVACBuilderUI() {
        String one   = "";
        String two   = "";
        String three = "";
        String four  = "";
        ItemCarrier item = new ItemCarrier(  one, two, three, four);
        
        list.add(item);
        
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        // netBeans generated GUI stuff here

        );

        pack();
    }// </editor-fold>

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new HVACBuilderUI().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JSeparator jSeparator3;
    private javax.swing.JSeparator jSeparator4;
    private javax.swing.JTable jTable1;
    // End of variables declaration

    
}


 

[Rob Camick]

list.add(item);   

Although I doubt the above line is the problem (since the table has not yet been created), when working with models updates should be done to the "model" not the "list" structre that was used to create the model. So get in the habbit of using:

myTable.addItem(item);

This will ensure that the model notifies the table of the changes.

If you need further help then you need to create a SSCCE (Short, Self Contained, Compilable and Executable, Example Program), that demonstrates the incorrect behaviour (as has already been suggested).

And there is a Swing forum, did you not notice the moderator moved one of your previous postings?

[Geoff Jefferson]

Okay, and thanks. I'll be sure to post to the appropriate forum next time.

[Rob Spoor]

And a moderator moved this one as well