Formulario de cadastro utilizando GWT

package com.java2s.gwt.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.Grid;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.Widget;

public class GWTClient implements EntryPoint{
   Label nameLabel = new Label("Name:");
   TextBox nameBox = new TextBox();
   Label addrLabel = new Label("Address:");
   TextBox addrBox = new TextBox();
   Label phoneLabel = new Label("Phone number:");
   TextBox phoneBox = new TextBox();
   Button button = new Button("Submit");

   Grid grid = new Grid(4, 2);
   
   public void onModuleLoad() {
      grid.setWidget(0, 0, nameLabel);
      grid.setWidget(0, 1, nameBox);
      grid.setWidget(1, 0, addrLabel);
      grid.setWidget(1, 1, addrBox);
      grid.setWidget(2, 0, phoneLabel);
      grid.setWidget(2, 1, phoneBox);
      grid.setWidget(3, 1, button);
      RootPanel.get().add(grid);
      
      button.addClickListener(new ClickListener() {
         public void onClick(Widget sender) {
            grid.setVisible(false);
            RootPanel.get().add(
                  new Label("Thanks for your submission."));
            Window.alert("Submit name=" + nameBox.getText()
                  + "\naddress=" + addrBox.getText() + "\nphone="
                  + phoneBox.getText());
         }
      });
   }
}