Doing new JTable doesn't "update" the table on the screen

Question

Hello
I am writing a program in java/swing which has several "layers" of panels. In the constructor method of the frame (using JInternalFrame) I create a new instance of JTable, place it inside JScrollPane which is then inside JSplitPane and then place that as the frame content pane.
In this program I run an sql command and the table is the result from that. Every time I execute a query it should update the table with the new results.
What is bothering me now is that when I execute a query I call new JTable() on the variable that held the JTable() object created on startup. When I create a new instance of JTable() and place it in this variable nothing seems to happen. What I need is some kind of "refresh" button. I tried to construct the whole window again but then the program started behaving odd so I gave up that method.
So, does anyone know how to do this?
The code behind this class can be found at http://www.heilabu.net/kari/Session.java (little commented, sorry :/)
You can see the table being constructed in the constructTable() method.
If I am a bit unclear I apologize, don't know all these technical words in english ;)
Thanks in advance!

Answer 1

You really need to use a table model. The table you created is great and once that is in you shouldn't mess with it. Instead, when you create the table be sure to create it sort of like this:
DefaultTableMode dtm = new DefaultTableModel(<various constrcutors use the one suited for you>);
JTable table = new JTable(dtm);
To set different data on the table set it in the table model and then refresh the table, also through the table model. This works perfectly every time.
dtm.setDataVector(---) <- 2 methods, one for vectors and one for arrays...
dtm.fireTableChanged();
the folowing code shows exactly how to use it
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;
public class RandomTable extends JFrame
GridBagLayout gbl = new GridBagLayout();
JPanel buttonPanel = new JPanel(gbl);
JTable table = null;
DefaultTableModel dtm = null;
JScrollPane tableSP = new JScrollPane();
JButton randomButton = new JButton("Randomize");
Object[] headers = { "a", "b", "c", "d", "e" };
public RandomTable()
this.getContentPane().setLayout(gbl);
randomButton.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent evt)
dtm.setDataVector(randomStrings(), headers);
this.dtm = new DefaultTableModel();
this.table = new JTable(dtm);
this.dtm.setDataVector(randomStrings(), headers);
this.tableSP.getViewport().add(table);
this.buttonPanel.add(randomButton, new GridBagConstraints(1, 1, 1, 1, 0.0, 0.0,GridBagConstraints.CENTER, GridBagConstraints.NONE, new Insets(0, 0, 0, 0), 0, 0));
this.getContentPane().add(buttonPanel, new GridBagConstraints(1, 2, 1, 1, 0.0, 0.0,GridBagConstraints.CENTER, GridBagConstraints.NONE, new Insets(3, 6, 6, 6), 0, 0));
this.getContentPane().add(tableSP, new GridBagConstraints(1, 1, 1, 1, 1.0, 1.0,GridBagConstraints.CENTER, GridBagConstraints.BOTH, new Insets(6, 6, 3, 6), 0, 0));
this.setSize(300, 300);
public Object[][] randomStrings()
Random rand = new Random();
int rowCount = Math.abs(rand.nextInt())%50;
int colCount = headers.length;
Object[][] array = new Object[rowCount][colCount];
for(int row = 0; row < rowCount; row++)
for(int col = 0; col < colCount; col++)
array[row][col] = Long.toString(Math.abs(rand.nextLong())%100);
return array;
public static void main(String[] args)
RandomTable rt = new RandomTable();
rt.setVisible(true);
}