enter code hereTengo una tabla de celdas y las columnas contienen algunos números. Quiero agregar una fila adicional al final de la tabla que contendrá el total de cada columna. ¿Hay alguna manera de hacer esto?

Siguiendo es mi código:

   import java.util.*;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.cellview.client.CellTable;
import com.google.gwt.user.cellview.client.TextColumn;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.view.client.ListDataProvider;

public class TestProject implements EntryPoint 
{

 private static int totalSalary=0;
 private static class Contact 
 {
        private final String salary;
        private final String name;

        public Contact(String name, String salary) 
        {
          this.name = name;
          this.salary = salary;
        }
 }

private static List<Contact> CONTACTS = Arrays.asList(new Contact("John","100000"), 
                                                      new Contact("Mary", "200000"), 
                                                      new Contact("Zander", "300000"));
/**
 * This is the entry point method.
 */
public void onModuleLoad() 
{
    final CellTable<Contact> table = new CellTable<Contact>();

    // Create name column.
    TextColumn<Contact> nameColumn = new TextColumn<Contact>() 
    {
      @Override
      public String getValue(Contact contact) 
      {
        return contact.name;
      }
    };

    // Create address column.
    TextColumn<Contact> addressColumn = new TextColumn<Contact>() 
    {
      @Override
      public String getValue(Contact contact) 
      {
        totalSalary+=Integer.parseInt(contact.salary);
        return contact.salary;
      }
    };

    // Add the columns.
    table.addColumn(nameColumn, "Name");
    table.addColumn(addressColumn, "Salary");

    // Create a data provider.
    ListDataProvider<Contact> dataProvider = new ListDataProvider<Contact>();

    // Connect the table to the data provider.
    dataProvider.addDataDisplay(table);

    // Add the data to the data provider, which automatically pushes it to the
    // widget.
    final List<Contact> list = dataProvider.getList();
    for (Contact contact : CONTACTS) {
      list.add(contact);
    }

    // We know that the data is sorted alphabetically by default.
    table.getColumnSortList().push(nameColumn);

    Contact total = new Contact("Total: ",totalSalary+"");
    list.add(total);



    // Add it to the root panel.
    RootPanel.get().add(table);
    //RootPanel.get().add(add);
}

}