TableModelListener firing twice.

[Jw Jones]

Greetings, all.

Back with another prob, possibly?? I have an MVC app I'm working on & have added a JTable with a TableModel I've extended from AbstractTableModel. I've added a TableModelListener() to the Controller class to see when a JCheckBox has changed which is the only editable column in the JTable.

For some reason, the TableModelListener ends up firing twice. The first time it returns whatever the value was before clicking the JCheckBox. The second time, it ends ups returning the current value. Both calls register as an "UPDATE" event.

Is it normal for the TabelModelListener to be called twice from one change? If not, any hints to what might be causing this? I'll try to find the relevant code, put it takes some poking around with this mvc app & around 35K lines of code.

Thanks!

-Jay

[Rob Spoor]

Can you show us your table model code?

[Jw Jones]

Rob Prime wrote:Can you show us your table model code?

Here is my complete table model code:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package View;

import javax.swing.table.AbstractTableModel;
import java.util.Vector;
import javax.swing.event.TableModelListener;
/**
 *
 * @author jjones
 */
public class AppTableModel extends AbstractTableModel{
    private Object[][] m_Data = null;
    private String[] m_ColumnNames =null;


   

    public int getColumnCount() {
        if(!(m_ColumnNames==null))
            return m_ColumnNames.length;
        else
            return 0;
  }
    public int getRowCount() {
        if(!(m_Data==null))
            return m_Data.length;
        else return 0;
  }
    public String getColumnName(int col) {
        return m_ColumnNames[col].toString();
    }


    public void addTableModelListener(TableModelListener tml)
    {
       System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" +
                           "Adding TableModelListener()");
       TableModelListener[] tmls = super.getTableModelListeners();
       if(!(tmls==null) && tmls.length>0)
       {
           // Only allow one "AppsTableModelListener"'s to be added.
           for(TableModelListener tmLis: tmls)
           {
               if(tmLis.getClass().getSimpleName().equalsIgnoreCase("AppsTableModelListener"))
                   return;
           }
       }
       super.addTableModelListener(tml);
    }
    public AppTableModel(Vector rows, Vector cols)
    {       
        m_ColumnNames = new String[cols.size()];
        int i=0;
        for(Object colName: cols)
        {
            if(colName.getClass().getSimpleName().equalsIgnoreCase("String"))
            {
                m_ColumnNames[i]=(String)colName;
                System.out.println("COLUMN NAME: " + m_ColumnNames[i]);
                i++;
            }
            else
            {
                System.out.println(colName.getClass().getSimpleName() + " " + i);
            }
        }
        //super(rows, cols);
        m_Data = new Object[rows.size()][cols.size()];
        int curCol = 0;
        int curRow = 0;
        for(Object row: rows)
        {
            if(row.getClass().getSimpleName().equalsIgnoreCase("Vector"))
            {
                Vector data = (Vector)row;
                curCol=0;
                for(Object cell: data)
                {
                    m_Data[curRow][curCol] = cell;
                   System.out.println("Cell at " + curRow + ", " + curCol + " Editable:" +
                                      isCellEditable(curRow, curCol));
                    System.out.println("Setting m_Data[" + curRow + "][" + curCol + "] to " + cell);
                    curCol++;
                }                
            }
            curRow++;
        }

       
    }

    
    /*public boolean isCellEditable()
    {
        return false;
    }
    */
    
    /*
         * JTable uses this method to determine the default renderer/
         * editor for each cell.  If we didn't implement this method,
         * then the last column would contain text ("true"/"false"),
         * rather than a check box.
         */
   
        public Class getColumnClass(int c) {
            System.out.println("Col TO GET: " + c);
            if(!(getValueAt(0,c)==null))
            {
                System.out.println("RETURNING " + getValueAt(0,c).getClass());
                return getValueAt(0, c).getClass();
            }
            else
            {
                System.out.println("RETURNING NULL");
                return null;
            }
        }
   public Object getValueAt(int row, int col) {
        return m_Data[row][col];

    }
   
   public TableModelListener[] getAppTableModelListeners()
   {
       return this.getTableModelListeners();
   }


   




    /*
     * Don't need to implement this method unless your table's
     * editable.
     */
    
    public boolean isCellEditable(int row, int col) {
        //Note that the data/cell address is constant,
        //no matter where the cell appears onscreen.
        if (col<1 )
            return true;
        else return false;


    }

     /*
     * Don't need to implement this method unless your table's
     * data can change.
     */
    
    public void setValueAt(Object value, int row, int col) {

    System.out.println("setValueAt(" + value + ", " + row + ", " + col + ") called.");
        m_Data[row][col] = value;
        System.out.println("Number of TableModelListeners: " + this.getAppTableModelListeners().length);
        //super.setValueAt(value, row, col);
        fireTableCellUpdated(row, col);

    }

Please forgive all the crazy System.out... testing junk.

[Jw Jones]

Narrowed it down a bit further. If I check/uncheck the JCheckBox with the spacebar, it only fires once. If I check/uncheck it with a left-mouse click, it fires twice. Strange...

[Rob Spoor]

Since you are only calling fireTableCellUpdated once, it seems that setValueAt is called twice. I have no idea why though.

I did notice two... odd coding practices:
1) !(someRef == null)
Why not just write someRef != null?

2) colName.getClass().getSimpleName().equalsIgnoreCase("String")
If instanceof is not good, you can still use a simpler trick:

colName.getClass() == String.class
tmLis.getClass() == AppsTableModelListener.class
row.getClass() == Vector.class

It's shorter, faster and easier to read.

[Jw Jones]

Rob Prime wrote:Since you are only calling fireTableCellUpdated once, it seems that setValueAt is called twice. I have no idea why though.

I did notice two... odd coding practices:
1) !(someRef == null)
Why not just write someRef != null?

2) colName.getClass().getSimpleName().equalsIgnoreCase("String")
If instanceof is not good, you can still use a simpler trick:

colName.getClass() == String.class
tmLis.getClass() == AppsTableModelListener.class
row.getClass() == Vector.class

It's shorter, faster and easier to read.

Thanks for the coding tips, Rob. Your way does seem much easier to read.

I have removed any MouseListener that I know of, but I am still having getColumnClass & getValueAt methods called from the TableModel just by mousing over a row in the table. This isn't normal without a mouse listener for JTables, is it?

[Mikko Kohtamäki]

Well i tried your code though setValue is called ONCE and getValue or getColumnClass are called sometimes twice or by hovering mouse because the JTable will check for toolTipText by constructing renderer component

[Jw Jones]

I figured it out. For some reason I was removing & re-adding the mouse listeners for the JTable. With some of the changes I had made, I suppose it ended up duplicating them causing this funky behavior.