add row and column to jTable in one loop

I am working in NetBeans IDE, language Java, the main class is JFrameForm.

I have a jTable tab with just one row and one column, button and jTextField en, where type should be integers. The input is variable n.

I need to create matrix with n rows and n columns. So n x n dimension of matrix as a jTable.

After click on the button, variable n will be saved as dimension and loop will start add the column and row till n.

The code is following:

private void sendMouseClicked(java.awt.event.MouseEvent evt) {                                    
        DefaultTableModel model = (DefaultTableModel) tab.getModel();

        String sn=en.getText();
        int n=Integer.valueOf(sn);

        for(int j=2;j<=n;j++){
            model.addColumn(null); // I know this is wrong
            model.addRow(new Object[]{test.getText()+j});
            test.setText(test.getText()+j);
        }
    }         

I got error

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 1

The cells should be empty.

Please help me to input the column. What is object there?

set column names to JTable and then add rows in JTable..

private void sendMouseClicked(java.awt.event.MouseEvent evt) {                                    
    String sn=en.getText();
    int n=Integer.valueOf(sn);
    java.util.Vector columns = new java.util.Vector();
    columns.add("Your Column Name");
    java.util.Vector rows = new java.util.Vector();
    for(int j=2;j<=n;j++){
        java.util.Vector row = new java.util.Vector();
        row.add(test.getText()+j);
        rows.add(row);
        test.setText(test.getText()+j);
    }
    DefaultTableModel model = new DefaultTableModel(rows, columns);
    tab.setModel(model);
}

this will work..