Good afternoon,

I have the following problem and I want to visualize all the data of an arrayList of type Counter, which is an object that I have created, and I do not know how to add all the counters to that table because I have only managed to insert 1.

The main class is the following

public class main {
public static void main(String[] args) {

   ArrayList<Contador> contadores = new ArrayList<Contador>();
   contadores.add(new Contador("P44152F", "10:00:00", "21/03/2017", 100.00));
   contadores.add(new Contador("R41525R", "11:00:00", "22/03/2017", 99.00));

   GroupableHeaderExample frame = new GroupableHeaderExample(contadores);
   frame.addWindowListener( new WindowAdapter() {
     public void windowClosing( WindowEvent e ) {
       System.exit(0);
     }
   });
   frame.setVisible(true);
}
}

GroupableTableHeaderExample class code

public class GroupableHeaderExample extends JFrame {
public GroupableHeaderExample(ArrayList<Contador> contadores) {
super( "Tabla Ejemplos Header" );
JTable table = null;
//Se crea el vector para almacenar todo el array
Vector <Contador> datos = new Vector();
for(int i=0;i<contadores.size();i++){
    datos.addElement(contadores.get(i));
}

//Se crea el modelo de la cabecera
DefaultTableModel dm = new DefaultTableModel();
for(int i=0;i<datos.size();i++){
    dm.setDataVector(
    new Object[][]{{datos.get(i).getFecha(),datos.get(i).getLectura(),"0"}},
    new Object[]{"Fecha","Lectura","Consumo"});

    //Creación de la tabla con el modelo de cabecera principal
    table = new JTable( dm ) {
      protected JTableHeader createDefaultTableHeader() {
          return new GroupableTableHeader(columnModel);
      }
    };

    //Se crea un segundo modelo
    TableColumnModel cm = table.getColumnModel();//Se coge el modelo del header principal
    ColumnGroup contador = new ColumnGroup(datos.get(i).getSerialNumber());//Se crea un grupo
    contador.add(cm.getColumn(1));
    contador.add(cm.getColumn(2));
    GroupableTableHeader header = (GroupableTableHeader)table.getTableHeader();
    header.addColumnGroup(contador);
}


JScrollPane scroll = new JScrollPane(table);
getContentPane().add( scroll );
setSize( 400, 120 ); 
}
}

The result that I have at the moment is the following:

As I mentioned before, it only shows me 1 counter, and I have two in the arrayList, and I can not find a way to put the two together.

Could someone help me organize the code correctly so that all the elements of the arrayList come out?

If anyone can lend me a hand, it would be very helpful. Thanks in advance