MultiLine Headers with Icons for a JTable

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posted 20 years ago

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Hi,

I want multi line headers for a table with header icons. For multiline headers I am extending the renderer class to a JList & it implements the TableCellRenderer interface.

The problem is, it is showing me the multiline header for each column but when I click on any one of the headers it shows me the same icon twice for a single header. Is there any way out wherein I can just display the icon once on a mouse click.

I think the problem is b'coz the renderer is being called twice - once when the table is initialised for showing the multi line header & the other on a mouse click for displaying the icon.

Can anyone suggest me as to why is this happening...

Any help will be appreciated..

Thanx.

Regards,
-Neha.

Craig Wood

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Posts: 1535

posted 20 years ago

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import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.table.*;
 
public class HeaderTest
{
 public HeaderTest()
 {
 JTable table = createTable();
 ImageIcon icon = new ImageIcon(loadImage());
 JTableHeader header = table.getTableHeader();
 TableColumnModel colModel = header.getColumnModel();
 for(int j = 0; j < colModel.getColumnCount(); j++)
 colModel.getColumn(j).setHeaderRenderer(new HeaderRenderer(icon));
 
 JFrame f = new JFrame();
 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 f.add(new JScrollPane(table));
 f.setSize(400,400);
 f.setLocation(200,200);
 f.setVisible(true);
 }
 
 private JTable createTable()
 {
 String[] headings = {
 "<html><center>column 1 design</center></html>",
 "<html><center>column 2 name</center></html>",
 "<html><center>column 3 id number</center></html>",
 "<html><center>column 4 size</center></html>"
 };
 int rows = 4, cols = 4;
 String[][] data = new String[rows][cols];
 for(int row = 0; row < rows; row++)
 for(int col = 0; col < cols; col++)
 data[row][col] = "item " + (row * cols + col + 1);
 return new JTable(data, headings);
 }
 
 private BufferedImage loadImage()
 {
 String fileName = "images/middle.gif";
 BufferedImage image = null;
 try
 {
 URL url = getClass().getResource(fileName);
 image = ImageIO.read(url);
 }
 catch(MalformedURLException mue)
 {
 System.err.println("Bad URL: " + mue.getMessage());
 }
 catch(IllegalArgumentException iae)
 {
 System.err.println("Image argument: " + iae.getMessage());
 }
 catch(IOException ioe)
 {
 System.err.println("Unable to read image: " + ioe.getMessage());
 }
 return image;
 }
 
 public static void main(String[] args)
 {
 new HeaderTest();
 }
}
 
class HeaderRenderer extends DefaultTableCellRenderer
{
 Icon icon;
 
 public HeaderRenderer(ImageIcon icon)
 {
 this.icon = icon;
 }
 
 public Component getTableCellRendererComponent(JTable table,
 Object value,
 boolean isSelected,
 boolean hasfocus,
 int row, int col)
 {
 setIcon(icon);
 setHorizontalAlignment(CENTER);
 setVerticalTextPosition(TOP);
 setText((String)value);
 return this;
 }
}

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