import java.util.ArrayList; import java.util.Vector; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; public class Main { public static void main(String[] argv) throws Exception { DefaultTableModel model = new DefaultTableModel(); JTable table = new JTable(model); model.addColumn("Col1"); model.addRow(new Object[] { "r1" }); model.addRow(new Object[] { "r2" }); model.addRow(new Object[] { "r3" }); Vector data = model.getDataVector(); Vector row = (Vector) data.elementAt(1); // Overwrite the first row with the copy Vector firstRow = (Vector) data.elementAt(0); for (int i = 0; i < row.size(); i++) { firstRow.set(i, row.get(i)); } JFrame f = new JFrame(); f.setSize(300, 300); f.add(new JScrollPane(table)); f.setVisible(true); } }