Centering Text in a JTable

I would like to center the text in some of my columns. So far, the only way I have found to do this is to create a new CellRenderer which extends JLabel and implements TableCellRenderer. I then add this cell renderer to the appropriate column. This sure does seem like a complicated solution to do something simple. Am I missing something?

Thanks

Nope, you aren't missing anything. I went searching for the same answer and I landed up using the tableCellRenderer classes to accomplish this. It does seem like overkill, but when you do it a couple of times it is actually quite fast to incorporate into the code.

Cheers,
Rachel
[ November 09, 2004: Message edited by: Rachel Swailes ]

You can always just use DefaultTableCellRenderer (which allready implements TableCellRenderer and extends JLabel). This will also perform faster - check the implementation notes.
D.

So you can use the DefaultTableCellRenderer and then inside that you override the label to center the text?

You don't necessarily have to do that. DefaultTableCellRenderer *extends* JLabel so you can do :

D.

OMG! That's like way easier to do the simple stuff.

Thanks Don!

Don Kiddick wrote:You don't necessarily have to do that. DefaultTableCellRenderer *extends* JLabel so you can do :

DefaultTableCellRenderer dtcr = new DefaultTableCellRenderer(); dtcr.setHorizontalTextPosition(DefaultTableCellRenderer.CENTER);

Sorry to drag up an ages-old post, but could someone help me understand how this advice is implemented? Where do I declare the DefaultTableCellRenderer and how do I actually apply it to cells in the jTable?

Thanks,

Adam

Adam Price wrote:Sorry to drag up an ages-old post, but could someone help me understand how this advice is implemented? Where do I declare the DefaultTableCellRenderer and how do I actually apply it to cells in the jTable?

Have you gone through the Sun Swing tutorial, specifically the JTable section? It's all pretty much laid out for you there.

import javax.swing.*;
import javax.swing.table.*;

public class AlignTest {
    private JScrollPane getContent() {
        JTable table = new JTable(getModel());
        java.awt.Dimension d = table.getPreferredSize();
        table.setPreferredScrollableViewportSize(d);
        // You can set renderers for any TableColumn.
        // Set a renderer with center horizontal alignment in
        // TableColumn zero.
        TableColumn col = table.getColumnModel().getColumn(0);
        DefaultTableCellRenderer dtcr = new DefaultTableCellRenderer();  
        dtcr.setHorizontalAlignment(SwingConstants.CENTER);
        col.setCellRenderer(dtcr);
        // Default cell renderers are assigned/set by column class.
        // You can fetch default renderers and reconfigure them or
        // set new default renderers.
        // Query and alter the Integer class default cell renderer.
        TableCellRenderer tcr = table.getDefaultRenderer(Integer.class);
        System.out.println("tcr = " + tcr.getClass().getName());
        System.out.printf("tcr extends DefaultTableCellRenderer = %b%n",
            DefaultTableCellRenderer.class.isAssignableFrom(tcr.getClass()));
        DefaultTableCellRenderer renderer = (DefaultTableCellRenderer)tcr;
        System.out.println("renderer horizontalAlignment = " +
                            renderer.getHorizontalAlignment()); // 4:right
        renderer.setHorizontalAlignment(SwingConstants.CENTER);
        return new JScrollPane(table);
    }

private AbstractTableModel getModel() {
        return new AbstractTableModel() {
            public int getRowCount() { return 6; }

public int getColumnCount() { return 4; }

public Class getColumnClass(int col) {
                return getValueAt(0, col).getClass();
            }

public Object getValueAt(int row, int col) {
                int r = row+1;
                int c = col+1;
                if(col < 2) {
                    return String.valueOf(r) + c;
                } else {
                    return Integer.valueOf(10*r + c);
                }
            }
        };
    }

public static void main(String[] args) {
        AlignTest test = new AlignTest();
        JOptionPane.showMessageDialog(null, test.getContent(), "",
                                      JOptionPane.PLAIN_MESSAGE);
    }
}

Craig Wood wrote:import javax.swing.*; import javax.swing.table.*; public class AlignTest { private JScrollPane getContent() { << SNIP >> } }

That is very helpful - thank you. I am using netbeans* and based on your tip, I added
as pre-creation code on the main panel in which the JTable resides. Then I used the Table Contens ->Columns -> renderer option to set the custom renderer as dtcr. That works for the column data, and I think it points me in the right direction to figure out how to center the column headers as well.

Thanks again!

-Adam

*I know that isn't a good way to learn Java, but I am not trying to learn java - I am trying to write a program that will help me with my graduate school research on chemical adsorption isotherms.