column margin in JTable

[Chetan Sharma]

Hi,
How can I control the column margin of the header of the table ?
Either use
TableColumnModel.setColumnMargin() or
Jtable.setIntercellSpacing()
the result is same.
When I view The applet in Jre1.3.1 The Column margin is set in the data cells and not in Table Header. Use any value for columnmargin, the header has always margin of 0 and the data cells gets the req. margin.
When I view the same applet in JRe 1.4.1_01 the margin is set both in header and data cells.
So is there any way in jre1.4.1 that can set the header margin as 0 and data margin as 1. or
In jre 1.3.1 How can I set the margin in header also.
Any Solution ?

[Amit Mathur]

I am also facing the same problem in JRE1.4.1.
Can anyone help us out?
There must be a way to differentiate between setting column margin for only the header and not for the data rows??

[Chantal Ackermann]

my solution:
I have written a tablecellrenderer that puts an empty border around the rendering component (for example the JLabel for text values). this has the same visual effect as setting the row margin but you are way more flexible. and the row header does not get messed up.
be sure to extend DefaultTableCellRenderer or overwrite the ui updating methods as does this class. (performance reasons, see API)
Chantal

[Amit Mathur]

Thanks for the response...but I am unable to implement it. We too have a custom CellRenderer but setting a border for it and setting interCellSpacing(0) in JRE1.4.1 does not help!
Can you give a code sample to create empty border for the renderer.
Thanks

[Chantal Ackermann]

here is a sample. you have to set a preferred size for for the table as it computes the size of the cells without counting the border of the label in. so the cells get to small without adding the scrollpane, just by calling pack on the frame with the table.
I hope this is what you need...
Chantal
SAMPLE CODE:

/*
 *  BorderCellRendererTest.java
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
/**
 *  $Source$ <br>
 *  Last modified: $Date$ <br>
 *  $Revision$ <br>
 *
 *
 * @author    chantal
 */
public class BorderCellRendererTest
{
private JFrame f = null;

public static void main( String[] args )
{
new BorderCellRendererTest();
}

public BorderCellRendererTest()
{
initComponents();
}

private void initComponents()
{
f = new JFrame( "JOptionPaneTest - dummy frame" );
f.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
final Container content = f.getContentPane();
content.setLayout( new BorderLayout() );
final Object[] row1 = new Object[]{"row1col1", "row1col2", "row1col2"};
final Object[] row2 = new Object[]{"row2col1", "row2col2", "row2col2"};
final Object[][] data = new Object[][]{row1, row2};
final Object[] cols = new Object[]{"header1", "header2", "header3"};
final JTable table = new JTable(data, cols);
table.setDefaultRenderer(Object.class, new BorderTableCellRenderer());
JScrollPane pane = new JScrollPane(table);
pane.getViewport().setPreferredSize(new Dimension(300,100));
content.add(pane, BorderLayout.CENTER);
f.pack();
// works only with > 1.4
f.setLocationRelativeTo( null );
// end > 1.4
f.setVisible( true );
}

public class BorderTableCellRenderer extends JLabel implements TableCellRenderer
{
public BorderTableCellRenderer()
{
super();
this.setBorder( BorderFactory.createEmptyBorder( 0, 20, 0, 20 ) );
}

public Component getTableCellRendererComponent( JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column )
{
setForeground( table.getForeground() );
setFont( table.getFont() );
setValue( value );
return this;
}

public void updateUI()
{
super.updateUI();
setForeground( null );
}

public void validate() { }

public void revalidate() { }

public void repaint( long tm, int x, int y, int width, int height ) { }

public void repaint( Rectangle r ) { }

public void firePropertyChange( String propertyName, boolean oldValue, boolean newValue ) { }

protected void setValue( Object value )
{
setText( ( value == null ) ? "" : value.toString() );
}

protected void firePropertyChange( String propertyName, Object oldValue, Object newValue )
{
// Strings get interned...
if ( propertyName == "text" )
{
super.firePropertyChange( propertyName, oldValue, newValue );
}
}
}
}

[Chetan Sharma]

Thanks A lot.
I implemented it this way. The Gui Looks Perfect.
But The real problem is that I want to set the Column margin differently for the Header and the table.
A present I followed the following steps.
1. set the column margin to 0
2. myTable.setShowGrid(false);
3. in the cell renderer create a border
But the result is that there is no margin in the cells. The Values to two cells aer very close.

[Chetan Sharma]

Thanks Chantal for the reply.
earlier I set the bgrid lines to false and used the border like
//this.setBorder(BorderFactory.createMatteBorder(0,0,1,1,Color.gray));
to create the lines between the cells.
So I could not give the margin between the cells.
Now I am using
this.setBorder( BorderFactory.createEmptyBorder( 1, 1, 1, 1 ) );
Now the margin is there between the cells values. But using this technique I encounter I problem. The first two columns are non editable and from the renderer I have set the background color to gray. Now The grid line is not visble between the first two columns. In other words the two cells get merged.
Any solution for this.
Thanks in advance

[Chantal Ackermann]

hi Chetan,
I have difficulties to imagine what you're trying to do in your interface.
- why don't you show the table grid if you want to avoid the "merge" of the two cells? (or you could increase the margin (=empty border) to seperate them more clearly)
- if you don't want to use the table grid there is always the possibility to simulate it through the border of the renderer, just as you did before. Borders are not exclusive: you can add as many borders to a component as you like. thus, you can add the empty border to increase the margin and you can add a matte or whatever border to simulate the grid.
did that answer your question?
Chantal

[Chetan Sharma]

I have to show the grid. My first 2 cols. are disabled and hence background of these 2 cols is gray. When I use empty border then there is no border line between the 1st 2 cols. In the rest of the cols it is Ok.

[Chantal Ackermann]

you can change the grid color (JTable API) or the backgound color of the disabled cells.
chantal