http://www.roseindia.net/java/example/java/swing/SetCellValues.shtml

import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;

public class SetCellValues{
JTable table;
public static void main(String[] args) {
new SetCellValues();
}

public SetCellValues(){
JFrame frame = new JFrame("Setting Cell Values in JTable");
JPanel panel = new JPanel();
String data[][] = {{"Vinod","MCA","Computer"},
{"Deepak","PGDCA","History"},
{"Ranjan","M.SC.","Biology"},
{"Radha","BCA","Computer"}};
String col[] = {"Name","Course","Subject"};
DefaultTableModel model = new DefaultTableModel(data, col);
table = new JTable(model);
SetData("Math",2,2);
SetData("Santosh",3,0);
JTableHeader header = table.getTableHeader();
header.setBackground(Color.yellow);
JScrollPane pane = new JScrollPane(table);
panel.add(pane);
frame.add(panel);
frame.setSize(500,150);
frame.setUndecorated(true);
frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public void SetData(Object obj, int row_index, int col_index){
table.getModel().setValueAt(obj,row_index,col_index);
System.out.println("Value is added");
}
}