Setting column headers in JTable

Question

I have the following JTable which uses a table model:

http://s17.postimage.org/7zfh3l4lr/Screen_Shot_2012_03_10_at_15_11_31.png

Instead of using, A,B,C,D etc. how can I define my own table names. This is my code

Here is the code for my table model, the frame creates an object from this table model and displays it in a JFrame.

package uk.ac.kcl.inf._4css1pra.spreadsheet;

import java.awt.Dimension;
import java.util.HashMap;
import java.util.Map;

import javax.swing.table.AbstractTableModel;

/**
 * @author imdad
 *
 */
public class Spreadsheet extends AbstractTableModel{

    private Map data = new HashMap();

    public int getColumnCount()
    {
        return 7;
    }

    /* (non-Javadoc)
     * @see javax.swing.table.TableModel#getRowCount()
     */
    public int getRowCount()
    {
        return 250;
    }

    public Object getValueAt(int row, int col)
    {
        return data.get(new Dimension(row, col));
    }

    public void setValueAt(Object data, int row, int col)
    {
        Dimension coord = new Dimension(row, col);
        this.data.put(coord, data);
        fireTableCellUpdated(row, col);

    }
}

Solution 1

Not sure how good this thing is but you can use DefaultTableModel instead of AbstractTableModel, which extends AbstractTableModel.

Here is the code for example purpose :

package jtable;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableModel;


public class TableIcon extends JFrame
{
    public TableIcon()
    {
        ImageIcon backIcon = getImage("/images/bac.png");
        ImageIcon exitIcon = getImage("/images/exit.png");
        ImageIcon forwardIcon = getImage("/images/forward.png");

        String[] columnNames = {"Picture", "Description"};
        Object[][] data =
        {
            {backIcon, "BACK"},
            {exitIcon, "EXIT"},
            {forwardIcon, "FORWARD"},
        };

        DefaultTableModel model = new DefaultTableModel(data, columnNames);
        JTable table = new JTable( model )
        {
            //  Returning the Class of each column will allow different
            //  renderers to be used based on Class
            public Class getColumnClass(int column)
            {
                return getValueAt(0, column).getClass();
            }
        };
        ImageIcon icon = new ImageIcon(getClass().getResource("/images/appIcon.png"));
        //model.addRow(new Object[]{icon, "Text"});
        //model.addRow(data[0]);
        table.setPreferredScrollableViewportSize(table.getPreferredSize());

        JScrollPane scrollPane = new JScrollPane( table );
        getContentPane().add( scrollPane );
    }

    private ImageIcon getImage(String path)
    {
        java.net.URL url = getClass().getResource(path);
        if (url != null)
            return (new ImageIcon(url));
        else
        {
            System.out.println(url);
            return null;
        }
    }

    public static void main(String[] args)
    {
        try
        {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        TableIcon frame = new TableIcon();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible(true);
    }

}

Here is the output :

Solution 2

You must implement getColumnName to do so.

see API

private String[] colNames = new String[] {"first", "second", "third"};

@Override
public String getColumnName(int col) {
    return colNames[col];
}

Comments

[mKorbel]

please edit your code with 1) setColumnNames(), code talking about AbstractTableModel 2) colNames <> col

[Angelo Fuchs]

@mKorbel to 1) I don't see why it would improve the example. 2) Well, of course colNames <> col. col is an index, colNames is an Array the combination of both returns the name, whats your point? (Sorry if I just don't get it.)

[mKorbel]

better would be read OP's code and add required method(s), then I'll up_vote your answer here, maybe suggerstion for use DefaultTableModelwill be better for OP (then both my comments will be deleted)

[Angelo Fuchs]

@mKorbel I see. I intentionally did not do so. But yeah, using DefaultTableModel would serve the OP fine, the answer of Gagandeep does that well, so I'll leave mine the way it is as a suggestion. Thanks for your input. (and btw, i read the ops code, I even pulled it over from pastebin, see my edit on the original post)

[nIcE cOw]

@AngeloNeuschitzer : Ahha, it seems, you suggesting overriding the getColumnName(...), that is a good thing too :-)

[Angelo Fuchs]

@GagandeepBali Yeah, I just added the annotation so it seems more clear now what I do.