у добавить столбец в сетку, когда я нажимаю кнопку ("backBtn"). Затем я получаю значение из текстового поля ("filterText"), и это будет имя нового столбца. Кто может мне помочь? Код из учебника, но мне нужно добавить новую функцию здесь. Спасибо ! Вы можете найти мой код в приложении. Сетка находится в классе "MyUI"

Это клиент CLAS

 package my.vaadin.app;

import java.io.Serializable;
import java.time.LocalDate;
import java.util.Date;

/**
 * A entity object, like in any other Java application. In a typical real world
 * application this could for example be a JPA entity.
 */
@SuppressWarnings("serial")
public class Customer implements Serializable, Cloneable {

    private Long id;

    private String firstName = "";

    private String datum = "";

    private String lastName = "";

    private LocalDate birthDate;

    private CustomerStatus status;

    private String email = "";

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    /**
     * Get the value of email
     *
     * @return the value of email
     */
    public String getEmail() {
        return email;
    }

    /**
     * Set the value of email
     *
     * @param email
     *            new value of email
     */
    public void setEmail(String email) {
        this.email = email;
    }

    /**
     * Get the value of status
     *
     * @return the value of status
     */
    public CustomerStatus getStatus() {
        return status;
    }

    /**
     * Set the value of status
     *
     * @param status
     *            new value of status
     */
    public void setStatus(CustomerStatus status) {
        this.status = status;
    }

    /**
     * Get the value of birthDate
     *
     * @return the value of birthDate
     */
    public LocalDate getBirthDate() {
        return birthDate;
    }

    /**
     * Set the value of birthDate
     *
     * @param birthDate
     *            new value of birthDate
     */
    public void setBirthDate(LocalDate birthDate) {
        this.birthDate = birthDate;
    }

    /**
     * Get the value of lastName
     *
     * @return the value of lastName
     */
    public String getLastName() {
        return lastName;
    }

    /**
     * Set the value of lastName
     *
     * @param lastName
     *            new value of lastName
     */
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    /**
     * Get the value of firstName
     *
     * @return the value of firstName
     */
    public String getFirstName() {
        return firstName;
    }

    /**
     * Set the value of firstName
     *
     * @param firstName
     *            new value of firstName
     */
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getDatum() {
        return datum;
    }

    /**
     * Set the value of firstName
     *
     * @param firstName
     *            new value of firstName
     */
    public void setDatum(String datum) {
        this.datum = datum;
    }

    public boolean isPersisted() {
        return id != null;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (this.id == null) {
            return false;
        }

        if (obj instanceof Customer && obj.getClass().equals(getClass())) {
            return this.id.equals(((Customer) obj).id);
        }

        return false;
    }

    @Override
    public int hashCode() {
        int hash = 5;
        hash = 43 * hash + (id == null ? 0 : id.hashCode());
        return hash;
    }

    @Override
    public Customer clone() throws CloneNotSupportedException {
        return (Customer) super.clone();
    }

    @Override
    public String toString() {
        return firstName + " " + lastName;
    }
}

Это класс MyUI

    package my.vaadin.app;

import java.util.List;

import javax.servlet.annotation.WebServlet;
import javax.swing.text.TableView;

import com.vaadin.annotations.Theme;
import com.vaadin.annotations.VaadinServletConfiguration;
import com.vaadin.event.ShortcutAction.KeyCode;
import com.vaadin.server.FontAwesome;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinServlet;
import com.vaadin.shared.ui.ValueChangeMode;
import com.vaadin.ui.Button;
import com.vaadin.ui.CssLayout;
import com.vaadin.ui.Grid;
import com.vaadin.ui.Grid.SelectionMode;
import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.Label;
import com.vaadin.ui.PasswordField;
import com.vaadin.ui.TextField;
import com.vaadin.ui.UI;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.ui.components.grid.HeaderCell;
import com.vaadin.ui.components.grid.HeaderRow;
import com.vaadin.ui.themes.ValoTheme;

/**
 * This UI is the application entry point. A UI may either represent a browser window 
 * (or tab) or some part of a html page where a Vaadin application is embedded.
 * <p>
 * The UI is initialized using {@link #init(VaadinRequest)}. This method is intended to be 
 * overridden to add component to the user interface and initialize non-component functionality.
 */
@Theme("mytheme")
public class MyUI extends UI {

    private CustomerService service = CustomerService.getInstance();
    private Grid<Customer> grid = new Grid<>(Customer.class);
    private TextField filterText = new TextField();
  //  private CustomerForm form = new CustomerForm(this);

    @Override
    protected void init(VaadinRequest vaadinRequest) {
        final VerticalLayout layout = new VerticalLayout();
        Label tancore = new Label();


        filterText.setPlaceholder("Meno ...");
        //filterText.addValueChangeListener(e -> updateList());
        //filterText.setValueChangeMode(ValueChangeMode.LAZY);

        Button clearFilterTextBtn = new Button(FontAwesome.TIMES);
        clearFilterTextBtn.setDescription("Clear the current name");
        clearFilterTextBtn.addClickListener(e -> filterText.clear());

        tancore.setCaption("TanCore s.r.o");
        CssLayout filtering = new CssLayout();
        filtering.addComponents(filterText, clearFilterTextBtn);
        filtering.setStyleName(ValoTheme.LAYOUT_COMPONENT_GROUP);

        Button addCustomerBtn = new Button("Pridaj zamestnanca");
        Button downloadXlsBtn = new Button("Stiahnuť ako .xls");
        Button loginBtn = new Button("Prihlásiť sa");
      //  Button addEmplBtn = new Button("Pridaj");
        Button backBtn = new Button("Vlož");
       downloadXlsBtn.setVisible(false);
        TextField name = new TextField();
        PasswordField pass = new PasswordField();

     //   addEmplBtn.setVisible(false);
        addCustomerBtn.setVisible(false);   
        backBtn.setVisible(false);
        filtering.setVisible(false);
        clearFilterTextBtn.setVisible(false);
        filterText.setVisible(false);

        addCustomerBtn.setStyleName(ValoTheme.BUTTON_PRIMARY);
        //.setStyleName(ValoTheme.BUTTON_PRIMARY);
        addCustomerBtn.setClickShortcut(KeyCode.ENTER);

        backBtn.addClickListener(e -> {

            //Here i want include the new data after click on the button

            //grid.addColumn(filterText.getValue()); -> That it's not good, because after click the Java will Warning you


            addCustomerBtn.setVisible(true);
            backBtn.setVisible(false);
            filtering.setVisible(false);
            clearFilterTextBtn.setVisible(false);
            filterText.setVisible(false);


        });

        addCustomerBtn.addClickListener(e -> {
            addCustomerBtn.setVisible(false);
            filtering.setVisible(true);
            backBtn.setVisible(true);
            clearFilterTextBtn.setVisible(true);
            filterText.setVisible(true);
            //addEmplBtn.setEnabled(true);

        });


        loginBtn.addClickListener(e -> {


            if(name.getValue().equals("admin"))
            {
                if(pass.getValue().equals("admin"))
        {
                name.setVisible(false);
                pass.setVisible(false);
                loginBtn.setVisible(false);
                addCustomerBtn.setVisible(true);
                  downloadXlsBtn.setVisible(true);
        }
            }

        });


        pass.setPlaceholder("Heslo ...");
        name.setPlaceholder("Meno ...");
        HorizontalLayout toolbar = new HorizontalLayout(name, pass, loginBtn,filtering, addCustomerBtn,backBtn,downloadXlsBtn);



       // grid.setSelectionMode(SelectionMode.MULTI);
        grid.setColumns("datum", "lastName","email","status");



       // grid.setStyleName(ValoTheme.BUTTON_PRIMARY);

        /*HeaderRow extraHeader = grid.prependHeaderRow();
        HeaderCell joinedCell = extraHeader.join("datum", "lastName");
        joinedCell.setText("Joined cell");*/

       HorizontalLayout main = new HorizontalLayout(grid);
       main.setSizeFull();
       grid.setSizeFull();
      //  main.setExpandRatio(grid, 1);

        grid.getColumn("datum").setWidth(100);
       // grid.getColumn("datum").set
      //  grid.getColumn("datum").set
        grid.getColumn("datum").setCaption("Dátum");
        grid.getColumn("lastName").setCaption("Adam");

        layout.addComponents(toolbar, main);

        // fetch list of Customers from service and assign it to Grid
        updateList();

        setContent(layout);




     //   form.setVisible(false);

        grid.asSingleSelect().addValueChangeListener(event -> {
            //if (event.getValue() == null) {
              //  form.setVisible(false);
            //} else {
              //  form.setCustomer(event.getValue());
            //}
        });
    }

    public void updateList() {
        List<Customer> customers = service.findAll(filterText.getValue());
        grid.setItems(customers);
    }

    @WebServlet(urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true)
    @VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
    public static class MyUIServlet extends VaadinServlet {
    }
}

Это класс CustomerForm.java

package my.vaadin.app;

import com.vaadin.data.Binder;
import com.vaadin.event.ShortcutAction.KeyCode;
import com.vaadin.ui.Button;
import com.vaadin.ui.DateField;
import com.vaadin.ui.FormLayout;
import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.NativeSelect;
import com.vaadin.ui.TextField;
import com.vaadin.ui.themes.ValoTheme;

public class CustomerForm extends FormLayout {

    private TextField firstName = new TextField("First name");
    private TextField lastName = new TextField("Last name");
    private TextField email = new TextField("Email");
    private NativeSelect<CustomerStatus> status = new NativeSelect<>("Status");
    private DateField birthdate = new DateField("Birthday");
    private Button save = new Button("Save");
    private Button delete = new Button("Delete");

    private CustomerService service = CustomerService.getInstance();
    private Customer customer;
    private MyUI myUI;
    private Binder<Customer> binder = new Binder<>(Customer.class);

    public CustomerForm(MyUI myUI) {
        this.myUI = myUI;

        setSizeUndefined();
        HorizontalLayout buttons = new HorizontalLayout(save, delete);
        addComponents(firstName, lastName, email, status, birthdate, buttons);

        status.setItems(CustomerStatus.values());
        save.setStyleName(ValoTheme.BUTTON_PRIMARY);
        save.setClickShortcut(KeyCode.ENTER);

        binder.bindInstanceFields(this);

        save.addClickListener(e -> this.save());
        delete.addClickListener(e -> this.delete());
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
        binder.setBean(customer);

        // Show delete button for only customers already in the database
        delete.setVisible(customer.isPersisted());
        setVisible(true);
        firstName.selectAll();
    }

    private void delete() {
        service.delete(customer);
        myUI.updateList();
        setVisible(false);
    }

    private void save() {
        service.save(customer);
        myUI.updateList();
        setVisible(false);
    }

}

Это класс CustomerService.java

package my.vaadin.app;

import java.time.LocalDate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * An in memory dummy "database" for the example purposes. In a typical Java app
 * this class would be replaced by e.g. EJB or a Spring based service class.
 * <p>
 * In demos/tutorials/examples, get a reference to this service class with
 * {@link CustomerService#getInstance()}.
 */
public class CustomerService {

    private static CustomerService instance;
    private static final Logger LOGGER = Logger.getLogger(CustomerService.class.getName());

    private final HashMap<Long, Customer> contacts = new HashMap<>();
    private long nextId = 0;

    private CustomerService() {
    }

    /**
     * @return a reference to an example facade for Customer objects.
     */
    public static CustomerService getInstance() {
        if (instance == null) {
            instance = new CustomerService();
            instance.ensureTestData();
        }
        return instance;
    }

    /**
     * @return all available Customer objects.
     */
    public synchronized List<Customer> findAll() {
        return findAll(null);
    }

    /**
     * Finds all Customer's that match given filter.
     *
     * @param stringFilter
     *            filter that returned objects should match or null/empty string
     *            if all objects should be returned.
     * @return list a Customer objects
     */
    public synchronized List<Customer> findAll(String stringFilter) {
        ArrayList<Customer> arrayList = new ArrayList<>();
        for (Customer contact : contacts.values()) {
            try {
                boolean passesFilter = (stringFilter == null || stringFilter.isEmpty())
                        || contact.toString().toLowerCase().contains(stringFilter.toLowerCase());
                if (passesFilter) {
                    arrayList.add(contact.clone());
                }
            } catch (CloneNotSupportedException ex) {
                Logger.getLogger(CustomerService.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        Collections.sort(arrayList, new Comparator<Customer>() {

            @Override
            public int compare(Customer o1, Customer o2) {
                return (int) (o2.getId() - o1.getId());
            }
        });
        return arrayList;
    }

    /**
     * Finds all Customer's that match given filter and limits the resultset.
     *
     * @param stringFilter
     *            filter that returned objects should match or null/empty string
     *            if all objects should be returned.
     * @param start
     *            the index of first result
     * @param maxresults
     *            maximum result count
     * @return list a Customer objects
     */
    public synchronized List<Customer> findAll(String stringFilter, int start, int maxresults) {
        ArrayList<Customer> arrayList = new ArrayList<>();
        for (Customer contact : contacts.values()) {
            try {
                boolean passesFilter = (stringFilter == null || stringFilter.isEmpty())
                        || contact.toString().toLowerCase().contains(stringFilter.toLowerCase());
                if (passesFilter) {
                    arrayList.add(contact.clone());
                }
            } catch (CloneNotSupportedException ex) {
                Logger.getLogger(CustomerService.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        Collections.sort(arrayList, new Comparator<Customer>() {

            @Override
            public int compare(Customer o1, Customer o2) {
                return (int) (o2.getId() - o1.getId());
            }
        });
        int end = start + maxresults;
        if (end > arrayList.size()) {
            end = arrayList.size();
        }
        return arrayList.subList(start, end);
    }

    /**
     * @return the amount of all customers in the system
     */
    public synchronized long count() {
        return contacts.size();
    }

    /**
     * Deletes a customer from a system
     *
     * @param value
     *            the Customer to be deleted
     */
    public synchronized void delete(Customer value) {
        contacts.remove(value.getId());
    }

    /**
     * Persists or updates customer in the system. Also assigns an identifier
     * for new Customer instances.
     *
     * @param entry
     */
    public synchronized void save(Customer entry) {
        if (entry == null) {
            LOGGER.log(Level.SEVERE,
                    "Customer is null. Are you sure you have connected your form to the application as described in tutorial chapter 7?");
            return;
        }
        if (entry.getId() == null) {
            entry.setId(nextId++);
        }
        try {
            entry = (Customer) entry.clone();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
        contacts.put(entry.getId(), entry);
    }

    /**
     * Sample data generation
     */
    public void ensureTestData() {
        if (findAll().isEmpty()) {


            for (int i = 31; i > 0; i--) {

                Customer c = new Customer();
                c.setDatum(i+".7");
                save(c);
            }
        }
    }

}

Я хочу иметь это в моем WebApp

Это на самом деле мой WebApp