Prevent selection of certain JTable cells

[Nicholas van Orton]

Hi folks,

At the moment, I'm putting together a date picker using a JTable, which looks something like this:

DefaultTableModel dtm = new DefaultTableModel();
JTable t table = new JTable(dtm);
 
dtm.addColumn("S");
dtm.addColumn("M");
dtm.addColumn("T");
dtm.addColumn("W");
dtm.addColumn("T");
dtm.addColumn("F");
dtm.addColumn("S");
 
Object row1[] = {"", "", "", "1", "2", "3", "4"};
Object row2[] = {"5", "6", "7", "8", "9", "10", "11"};
Object row3[] = {"12", "13", "14", "15", "16", "17", "18"};
Object row4[] = {"19", "20", "21", "22", "23", "24", "25"};
Object row5[] = {"26", "27", "28", "29", "30", "31", ""};
Object row6[] = {"", "", "", "", "", "", ""};
 
dtm.addRow(row1);
dtm.addRow(row2);
dtm.addRow(row3);
dtm.addRow(row4);
dtm.addRow(row5);
dtm.addRow(row6);

I'm not all that familiar with JTables, but I was just wondering if there is any way of preventing the blank cells (those that .equal("") in their respective arrays)?

Also, if a variable:

int date = 6;

was used to represent today's date, is there any way of searching through all the cells & selecting the cell that contains that value?

Any help with this would be very much appreciated.

[Craig Wood]

Here's an event-oriented solution. Another (untried) possibility is to write a cell renderer and, for the empty cells, do not show any changes for selection or focus. The cell would continue to be both selected and the focus owner; you just would not have any visual indication. Or, you could do both. Even tough this (event) approach removes the focus, the cell renderer still seems to consider the cell to have focus: cover and uncover the table to see the restored appearance-of-focus. Press the tab key to remove it.

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableModel;
 
public class CellSelection
{
    private JTable getTable()
    {
        DefaultTableModel dtm = new DefaultTableModel();
        JTable table = new JTable(dtm)
        {
            public boolean isCellEditable(int row, int col)
            {
                return !((String)getValueAt(row, col)).equals("");
            }
        };
 
        dtm.addColumn("S");
        dtm.addColumn("M");
        dtm.addColumn("T");
        dtm.addColumn("W");
        dtm.addColumn("T");
        dtm.addColumn("F");
        dtm.addColumn("S");
 
        Object row1[] = {"", "", "", "1", "2", "3", "4"};
        Object row2[] = {"5", "6", "7", "8", "9", "10", "11"};
        Object row3[] = {"12", "13", "14", "15", "16", "17", "18"};
        Object row4[] = {"19", "20", "21", "22", "23", "24", "25"};
        Object row5[] = {"26", "27", "28", "29", "30", "31", ""};
        Object row6[] = {"", "", "", "", "", "", ""};
 
        dtm.addRow(row1);
        dtm.addRow(row2);
        dtm.addRow(row3);
        dtm.addRow(row4);
        dtm.addRow(row5);
        dtm.addRow(row6);
 
        table.setCellSelectionEnabled(true);
        table.getSelectionModel().addListSelectionListener(
                    new CellSelectionListener(table));
        table.getColumnModel().getSelectionModel().addListSelectionListener(
                    new CellSelectionListener(table));
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        return table;
    }
 
    private JPanel getControl(final JTable table)
    {
        int value = 12;
        // find min and max values for JSpinner
        DefaultTableModel model = (DefaultTableModel)table.getModel();
        Vector rows = model.getDataVector();
        int min = Integer.MAX_VALUE;
        int max = Integer.MIN_VALUE;
        for(int j = 0; j < rows.size(); j++)
        {
            Vector row = (Vector)rows.get(j);
            for(int k = 0; k < row.size(); k++)
            {
                String s = (String)row.get(k);
                if(!s.equals(""))
                {
                    int n = Integer.parseInt(s);
                    if(n < min) min = n;
                    if(n > max) max = n;
                }
            }
        }
        SpinnerNumberModel dayModel = new SpinnerNumberModel(value, min, max, 1);
        final JSpinner spinner = new JSpinner(dayModel);
        spinner.addChangeListener(new ChangeListener()
        {
            public void stateChanged(ChangeEvent e)
            {
                int value = ((Integer)spinner.getValue()).intValue();
                // find the row and column for this value
                DefaultTableModel model = (DefaultTableModel)table.getModel();
                for(int row = 0; row < model.getRowCount(); row++)
                    for(int col = 0; col < model.getColumnCount(); col++)
                    {
                        String s = (String)model.getValueAt(row, col);
                        if(!s.equals(""))
                        {
                            int n = Integer.parseInt(s);
                            if(n == value)
                            {
                                table.changeSelection(row, col, false, false);
                                return;
                            }
                        }
                    }
            }
        });
        JPanel panel = new JPanel();
        panel.add(new JLabel("day of the month"));
        panel.add(spinner);
        return panel;
    }
 
    public static void main(String[] args)
    {
        CellSelection test = new CellSelection();
        JTable table = test.getTable();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(table));
        f.getContentPane().add(test.getControl(table), "South");
        f.pack();
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
class CellSelectionListener implements ListSelectionListener
{
    JTable table;
 
    public CellSelectionListener(JTable table) { this.table = table; }
 
    public void valueChanged(ListSelectionEvent e)
    {
        if(!e.getValueIsAdjusting())
        {
            int row = table.getSelectionModel().getAnchorSelectionIndex();
            int col = table.getColumnModel().getSelectionModel()
                           .getAnchorSelectionIndex();
            if(row == -1 || col == -1)
                return;
            if(((String)table.getValueAt(row, col)).equals(""))
            {
                table.clearSelection();
                KeyboardFocusManager.getCurrentKeyboardFocusManager()
                                    .clearGlobalFocusOwner();
            }
        }
    }
}

[Nicholas van Orton]

I see what you mean, this may just be a limitation on using a JTable?

Is there anyway to use the removeMouseListener() method on a JTable cell?

[Craig Wood]

this may just be a limitation on using a JTable?
possibly
Is there anyway to use the removeMouseListener() method on a JTable cell?
Not exactly. But you could try something creative as an alternative.
I tried overriding processMouseEvent in the JTable and it seemed to work but every now and then it failed. I was unable to find out who was getting around the processMouseEvent method.

            protected void processMouseEvent(MouseEvent e)
            {
                Point p = e.getPoint();
                int col = columnAtPoint(p);
                int row = rowAtPoint(p);
                if(col != -1 && row != -1)
                {
                    if(((String)getValueAt(row, col)).equals(""))
                    {
                        e.consume();
                        return;
                    }
                }
                super.processMouseEvent(e);
                System.out.printf("row = %d\tcol = %d\tid = %d%n", row, col, e.getID());
            }

Then I tried a GlassPane and it seems to work okay.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;
 
public class LimitedSelection
{
    private JTable getTable()
    {
        DefaultTableModel dtm = new DefaultTableModel();
        JTable table = new JTable(dtm)
        {
            public boolean isCellEditable(int row, int col)
            {
                return !((String)getValueAt(row, col)).equals("");
            }
        };
 
        dtm.addColumn("S");
        dtm.addColumn("M");
        dtm.addColumn("T");
        dtm.addColumn("W");
        dtm.addColumn("T");
        dtm.addColumn("F");
        dtm.addColumn("S");
 
        Object row1[] = {"", "", "", "1", "2", "3", "4"};
        Object row2[] = {"5", "6", "7", "8", "9", "10", "11"};
        Object row3[] = {"12", "13", "14", "15", "16", "17", "18"};
        Object row4[] = {"19", "20", "21", "22", "23", "24", "25"};
        Object row5[] = {"26", "27", "28", "29", "30", "31", ""};
        Object row6[] = {"", "", "", "", "", "", ""};
 
        dtm.addRow(row1);
        dtm.addRow(row2);
        dtm.addRow(row3);
        dtm.addRow(row4);
        dtm.addRow(row5);
        dtm.addRow(row6);
 
        table.setCellSelectionEnabled(true);
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        // who is listening...
        MouseListener[] listeners = table.getListeners(MouseListener.class);
        for(MouseListener listener : listeners)
            System.out.printf("listener = %s%n", listener.getClass().getName());
        return table;
    }
 
    public static void main(String[] args)
    {
        LimitedSelection test = new LimitedSelection();
        JTable table = test.getTable();
        Interceptor interceptor = new Interceptor(table);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(table));
        f.setGlassPane(interceptor);
        f.getGlassPane().setVisible(true);  // see JRootPane api
        f.pack();
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
/** Intercept MouseEvents and forward them if we like where they are going. */
class Interceptor extends JPanel implements MouseListener, MouseMotionListener
{
    JTable table;
 
    public Interceptor(JTable table)
    {
        this.table = table;
        setOpaque(false);
        addMouseListener(this);
        addMouseMotionListener(this);
    }
 
    public void mouseClicked(MouseEvent e)  { }
 
    public void mouseEntered(MouseEvent e)  { redispatchEvent(e); }
 
    public void mouseExited(MouseEvent e)   { redispatchEvent(e); }
 
    public void mousePressed(MouseEvent e)  { redispatchEvent(e); }
 
    public void mouseReleased(MouseEvent e) { redispatchEvent(e); }
 
    public void mouseDragged(MouseEvent e)  { }
 
    public void mouseMoved(MouseEvent e)    { redispatchEvent(e); }
 
    private void redispatchEvent(MouseEvent e)
    {
        Point dest = SwingUtilities.convertPoint(this, e.getPoint(), table);
        int col = table.columnAtPoint(dest);
        int row = table.rowAtPoint(dest);
        // row returns as zero when dest is over the table header
        if(dest.y < 0)                   // avoid table header
        {
            e.consume();
            return;
        }
        else if(col != -1 && row != -1)  // over a table cell
        {
            if(((String)table.getValueAt(row, col)).equals(""))
            {
                e.consume();
                return;
            }
        }
        table.dispatchEvent(SwingUtilities.convertMouseEvent(this, e, table));
    }
}